6mm wtin sheath cable

[timddo]

This site is advertising 6mm twin sheath as


Our cable is measured by the cross sectional area of the copper, eg. Our 1.84mm squared cable is equivalent to Automotive 4mm. This is very important when calculating voltage drop Cable can be cut to size and the staff can assist you in making the best selection. Price is per meter

so in theory it's AW6

price is $6.90 a meter


http://www.springers.com.au/product.asp?SKU=635

[TheRealAndy]

Not quite. That link shows 6mm2 cable, which is about somewhere between 9 adn 10 AWG.

8mm2 is roughly 8 AWG, or 8B&S. AWG and B&S are the same.

I have no idea what automotive cables are and how that measurment works. As far as I am concerned you should go on the actual conductor size

[finga]

What the maximum current load of your winch?

[timddo]

30Amps. is the circuit breaker.

so AW8...

I though i mite get it cheap. ::) at $6.9 instead of $11.00

oh well. The current installation is like 2mm x 2 cables ( dogy dealer).


Apparently automotive cabling includes the insulation.

[TheRealAndy]

30Amps is not that much. The smaller stuff (6mm2) will carry that much current. However, depending on the length of the cable you might get to much voltage drop.

How long is the cable going to be? We can work all that out for you!

[timddo]

30Amps is not that much. The smaller stuff (6mm2) will carry that much current. However, depending on the length of the cable you might get to much voltage drop.

How long is the cable going to be? We can work all that out for you!

Andy

About 6.5 meters or so to the switch, then it's an extra 2 meters to the winch

[TheRealAndy]

For 6mm2 cable, the voltage drop at 30A for an 8.5m run is roughly 3V, so a little to much.

Using 10mm2 cable, the voltage drop is about 0.9V. I would consder this acceptable

[oldboot]

10mm2 solar twin is a popular cable at the moment, some of the bias stores have it for use with lecky outboards.

Going to the solar shops for this mid sized cable is not at all a bad thaught......they will be using the stuff in volume with all the subsidised solar arround these days.

cheers

[tigermullet]

For 6mm2 cable, the voltage drop at 30A for an 8.5m run is roughly 3V, so a little to much.

Using 10mm2 cable, the voltage drop is about 0.9V. I would consder this acceptable


Thanks from me too. Could you give me an approximate voltage drop for a 6mm2 cable - 16amp draw with a 4 metre run?

It is not a big winch, co-located with a dedicated battery (in a separate compartment of course) - and solar panel for recharging - all sited at the bow. The run back to the helm position is 4 metres.

I think the wire might be enough and have installed the lot but confirmation from an expert would be greatly appreciated.

[deckie]

Over a one way cable run that long that'll be a considerable v drop if you only use say 8AWG/8sqmm cable and its still significant even with about 10sqmm stuff...but probably acceptable.
You really dont want to starve anchor winches.
Would need 10sqmm minimum i reckon working off what my local guy stocks. As a price guide he retails 10sqmm tinned for about $4/m and the 16sqmm is about $7 so its quite a jump up in price for the real big stuff over that kinda long run.

Tigermullet....if its one way 4m about 3-4% i reckon. Andy might know better tho coz i think he's knee deep in a spaghetti of wires at the moment.

[tigermullet]

Thanks very much Deckie. The 4m distance is one way because I had to go beneath the deck on an angle and then up to the helm position. My problem is not understanding various gauges - the wire was purchased as 6mm but what that means in mm2 is beyond me. The only thing I could go on was that the wire (not twin sheath) was advertised as being suitable for, or rated at, 45 amps.

[oldboot]

If the battery is located close to the winch, why are you running all the way back to the helm with the high current cabling? a relay set up and light cabling to the winch would be the way to go.

As far as the voltage drop in question.

its around half the distance and around half the current so the voltage drop will be arround a quarter of the previous example....and that is with out any tables or serious maths.

On the mater of voltage drop and motors........ in our boats we only have 12 volts.....so if one or two volts go missing it is s real problem.

In addition motors can draw quite a lot more than their rated current on start up and near stall.........when a motor labours due to lack of voltage, it will be trying to operate near stall so the nearer stall the more current is drawn..and the cycle continues.

So it is very important to avoid voltage drop in large DC motors.

You have spent good money on a winch.....heavier cable never hurt.

cheers

[deckie]

Thanks very much Deckie. The 4m distance is one way because I had to go beneath the deck on an angle and then up to the helm position. My problem is not understanding various gauges - the wire was purchased as 6mm but what that means in mm2 is beyond me. The only thing I could go on was that the wire (not twin sheath) was advertised as being suitable for, or rated at, 45 amps.
Ahhh ok thats a different thing. Bizzarre how screwed up and confusing these wire sizes are. Yepp 6mm cable is rated about 45A but thats smaller than 6sqmm which measures the cross sectional area of the internal wire itself (dont quote me on that) but probably the only way to keep it real and to guarantee u get the right stuff coz of all the different bloody names.
There's AWG/B&S/mm/sqmm :-?and i think the car racket even do it differently again. The clue is u said u bght it as rated 45A.

Someone correct me if wrong but this is how screwed up it is...the 6mm wire u have is probably 12AWG or 12B&S or about 3sqmm stuff :-? which would be rated to about 45A as u say.
In which case its smaller stuff than i thought and the v drop would probably be most likely about 6% over 4m. Sorry bud.

In general 12V stuff with motors suck the most of anything onboard...the stuff we get from say Whitworths/Bias etc is quoted usually as 4mm or 6mm or 8mm etc but the reason sqmm is generally used is because its how much is inside the insulation that matters. For general wiring onboard 4mm (18AWG/1sqmm i think ??) is plenty, u may want to go to 6mm for things like long cable runs to bigger bilge pumps or short runs to thirsty spotlights...then 8mm as they call it (which i think is about 8AWG/8sqmm and rated to about 80A) is used for stuff such as connecting battery to dist panel at the dash and maybe short runs to small winches.
The problem is distance...even tho the wire/cable might be rated to say 45A, once u start taking 16A over 4m u get V drop which can only be cured easily by simply going to a bigger cable.
If its 4m to the winch i'd be looking at 8AWG/8sqmm which i think is sold as 8mm cable at the big chandlery's ..which is 80A cable :-?...and would be a v drop of only 2-3%. Timmdo's got a lonnngggggg run and maybe a bigger winch tho by the sounds.
Sparkies are evil...why cant they just give us one bloody cable description.

[tigermullet]

Thanks Oldboot I am beginning to see the problem. I just followed the wiring diagram - the winch operating switch has 4 terminals 2 from the battery and two from (or to) the winch. I wouldn't know a relay if I fell over one.

I used the recommended size (as far as I understood it) and, as far as I can determine, with a cheap multimeter, there is nil detectable voltage drop i.e., volts read at the battery - and at the switch - were exactly the same, 12.7 volts. Of course, the voltage drop at the winch motor could be different.

[TheRealAndy]

Lol. AWG is the Same as B&S, thats the yankee wire guage. The Brits have (had) SWG, which is different to the yanks. Most european countries now use the IEC metric (mm2) size now, including australia. The standard sizes I remember are 1 1.5, 2.5, 4 , 6, 10, 16, 25 and 35. They go lower and higher, but I dont recall any of them. Most smaller stuff is in AWG or SWG.

1 volt of loss is ok, and should not affect motors to badly in a 12V system. If you need every last little bit of torque and that 1V is making a difference then you should be considering the next size up in motor.

Now the auto industry is really screwed, and I dont know how it works, because from my limited understanding as a sparky, you can only derate cable capacity based on insulation, you cant calculate current and voltage drop. So I dont get it. I am sure there is some common sense in there somewhere.

Tigermullet, I have a spreadsheet that I made for calculating voltage drop, based on olex cable resistance specs. Will do your calcs tomorrow when I get to work.

If anyone is looking for more info, the olex handbook is an excellent source of material. You can download it from the website, just look in the low voltage section.

[tigermullet]

Thanks Deckie, your slight confusion is a consolation and an excuse for me. If you don't fully understand the different terms, gauges etc., what hope have I got?

The winch came with a two wires leading into the housing. The wire I used was thicker than those. I am going to take a punt and leave things as they are - the bloody winch motor will just have to put up with it.

A few minutes ago I found a guide which says AWG 8 = 8mm2 and AWG 6 (yes, 6) = 13mm2. How nuts is that? Anyway, enough is enough - whoever dreamt up these ways of measuring should have been strangled at birth. The manufacturers of the winch also need a rev up - they could just as easily have said to use wiring as thick as the wires leading from the winch. But no, that would be too simple.

I really appreciate the responses received.

[deckie]

tm...i went thru all this nomenclature crap recently so its still fresh in the head.

upshot is... in general i wouldnt have thought u would want to use anything less than what the chandlery's sell as 8mm (which is probably 8sqmm cable) for any kind of anchor winch, even if the battery is right at the bow. In a nutshell it might be best to run some new bigger stuff. You might be pleasantly surprised the difference it makes.

[tigermullet]

I am going to read and re-read what you have posted TR Andy. i will also have a look at the olex handbook via the net. Some understanding might seep into my brain. Somehow, I knew the bloody French would have stuck their noses into the mess and introduced yet another measurement.

[tigermullet]

Thanks again Deckie. I actually asked for 8mm but guess what? The chandlery I chose does not stock it. Because the wire I used is thicker than the wires leading from the winch I am beginning to wonder whether I got AWG6 but the rating of 45 amp now has me worried - unless the amperage rating depends on the insulation. I've been trying to look through the Olex Handbook but it might as well have been written in Hebrew.

The winch seems to run ok - really rips in 8mm chain and handles a 27lb sand anchor like a feather. I wonder if the diameter of the bare wire can be measured accurately enough? If so, surely I could just calculate the mm2? Sounds too easy actually - there's bound to be yet another trap for the uninitiated.

[TheRealAndy]

From the olex handbook page 96:

6AWG = 13.3mm2
8AWG = 8.4mm2

[oldboot]

this page might be helpfull to a point

http://www.gxk.org.uk/info/wire.htm

DO NOT USE THE ABOVE LINKED TABLE FOR CALCULATING CURRENT CARRYING OF WIRES IN REAL SITUATIONS.....THE "WIRE RATING" LISTED IN THE END COLLUMN IS THEORETICAL FOR THE BARE WIRE AND ACCOUNTS FOR NO SAFETY FACTORS OR OTHER DESIGN CONCERNS.

it gives relative awg, swg and approximate diameters and mm2 for wires up to 10swg.

it recons
8awg is 8.4mm2 and 3.27mm diameter
10awg is 5.26mm2 and 2.59mm diameter

the diameters can be pretty close so ya will at least need a vernier and ya have to have the cable formed near pristine to get a good measurement.

I have a table with all sorts of stuff somewhere but it is burried.

If you are realy getting fussy, ya measure 1 strand and count the strands.

Possibly the easiest way is to use an uninsulated lug as a go, no go guage

cheers

[tigermullet]

Thanks Oldboot. I'm getting a great education here. Measurement with a vernier does look tricky and probably too difficult for me. Will go with the uninsulated lug method - sounds ideal.

[finga]

Please use the table Oldboot has put up as a cable size comparison reference only.
The wire ratings and the fusing figures are meaningless and misleading to the vast majority.
As an example there would be no way in hell would I be making 2.63mm square wire carry 35A or making 10mm carry 130A continously..or for any length of time for that matter.
But as a size comparison table it's pretty damn good.

Here's a table to look up cable sizes in relation to load and voltage that might be handy for some
http://www.rbeelectronics.com/wtable.htm
or for very quick calculations of voltage drop
http://www.kilowatts.com.au/calculator-voltage-drop.php

The Olex handbook Andy mentioned has been a mainstay as a cable reference source for sparky dudes for donkey's years.
It can be viewed here
http://storage.baselocation.com/olex.com.au/Media/Docs/OLC4283-Handbook-Generic-2010-d321e720-d680-41d2-bcd2-2d9c12372ad4.pdf

[TheRealAndy]

Thanks from me too. Could you give me an approximate voltage drop for a 6mm2 cable - 16amp draw with a 4 metre run?

It is not a big winch, co-located with a dedicated battery (in a separate compartment of course) - and solar panel for recharging - all sited at the bow. The run back to the helm position is 4 metres.

I think the wire might be enough and have installed the lot but confirmation from an expert would be greatly appreciated.

Righteo, the voltage drop for 6mm2 cable, 4M run drawing 16A would be 0.4V. I would not be complaining about that. That sort of voltage drop is perfectly acceptable.



Please use the table Oldboot has put up as a cable size comparison reference only.
The wire ratings and the fusing figures are meaningless and misleading to the vast majority.
As an example there would be no way in hell would I be making 2.63mm square wire carry 35A or making 10mm carry 130A continously..or for any length of time for that matter.
But as a size comparison table it's pretty damn good.

Here's a table to look up cable sizes in relation to load and voltage that might be handy for some
http://www.rbeelectronics.com/wtable.htm
or for very quick calculations of voltage drop
http://www.kilowatts.com.au/calculator-voltage-drop.php

The Olex handbook Andy mentioned has been a mainstay as a cable reference source for sparky dudes for donkey's years.
It can be viewed here
http://storage.baselocation.com/olex.com.au/Media/Docs/OLC4283-Handbook-Generic-2010-d321e720-d680-41d2-bcd2-2d9c12372ad4.pdf


Finga makes a very good point. Current carrying capacity depends on several things, however the common ones are ambient temperature, insulation grade, copper quality and the number of wires bundled together. All my calcs are done using the resistance values for tinned wire at 20ºC, and are for a single run of cable.

When I actually did this stuff for a living, we specified a particluar cable supplier for cable for each piece of equipment we manufactured. If the contract manufacturers where not able to source the same cable, we had to recaculate everything for the manufacturer of the cable they had sourced. They would only be allowed to continue to build the product once they had recieved and engineering directive to use the new cable.

If you want to run close to the limits of the cable, then you need the manufactures data on resistance and insulation grade, and then you need to derate according to temp and cable loom size.

[TheRealAndy]

I probably mislead timdo a bit too, I said that 1V in a 12V system is fine, which it is. However, if it were me personally, I would go for about 5% drop. That gives a little leeway. 10% (1.2V) is about the upper limit you want.

If I were buying the cable for this app, I would be happy with 10mm2, but I would prefer 16mm2 or even 25mm2 if the budget extended that far. Recently I settled for 10mm2 cause that was all I could get without buying a roll. I am still considering buying a roll of aflex 16mm2 twin if anyone is interested.

[timddo]

Andy

You are confusing me everyday


I measure the lengths this morning. 5 meters to the isolator. ( breaker) then 20 cm to the switch. From the switch is 3 meters to the winch.

I was thinking of using 10mm square to the breaker and switch, then 3 meters of 10mm to the winch. ( winch currenty has 6mm normal copper cable now.

Or should i got 16mm square to the breaker and then 10mm to the winch???

got my budget at $110 including gst for this little problem.

[deckie]

Hey Andy... problem was tm asked basis he thought he had 6sqmm stuff... but then it turns out its actually 6mm...clue being he was told its rated to 45A.
Started running new wire yet or still pulling out the old firetrap ?

[oldboot]

I should have put a quaification up with posting that link.
You will notice there is a disclaimer in the text, and ya have to realise that table was intended as a guide to the approximate fusing values of those wires.

The continuous current carrying is there to show what the wire will hold at, the table does not account for any safety factors or derating for how the wire is used or packaged.

I posted it because it had bare wire diamters.

In the civilised electrical world, we work on a rule of thumb of 10 amps per square mm of conductor.....with some corrections, for how and where the wire is used........and as Mr Wrigley says in the text...... often the limiting factor is the insulation not the wire.

NOW.....if you look into the American attitude to wire and current carrying in automobiles.......most of the civilised electrical people would be horrified how close to those end collumn figures the wiring in our motor vehicles actually is.

This american current carrying attitude predominates automotive wiring world wide.

Ya just have to look at a toyota headlight circuit.

but this gets off subject a bit.

I will go back and inster a caution.

cheers

[deckie]

timddo...$110 +gst for just the cable ? Right on budget for the 16sqmm stuff all the way that would be far better if u can. I mentioned the prices coz its a bit of a jump between the 10sqmm and 16sqmm but shop around.

Edit...i like overkill tho ;D..and spending other peoples money ;D 10sqmm probably good enough.

[TheRealAndy]

Andy

You are confusing me everyday


I measure the lengths this morning. 5 meters to the isolator. ( breaker) then 20 cm to the switch. From the switch is 3 meters to the winch.

I was thinking of using 10mm square to the breaker and switch, then 3 meters of 10mm to the winch. ( winch currenty has 6mm normal copper cable now.

Or should i got 16mm square to the breaker and then 10mm to the winch???

got my budget at $110 including gst for this little problem.

sorry mate, How about we calulate it all properly and work on max 5% voltage drop?

So the basic setup is 8.2m of cable in total? Can you tell us what winch it is so I can look up the actual specs on it?


As for cables, perhaps peterbo3 might be able to help you out if you can handle not using twin.

[oldboot]

Just to summarise a few things.

when we design wiring for electrical loads we have to consider the following in order.

The voltage of the system we are working on, because if system is very low voltage like our 12 or 24 volt boats and cars we can not afford to have much at all go missing, in some things 1 volt of voltage drop in a 12 volt system is a real problem

The current drawn by the piece of equipment, remember the item particularly a motor may draw very much more than its rated or more than the fuse or breaker for a short time or under certain situations...... fuses & breakers will hold twice their rated for a specified time often 60 seconds.

The circuit distance, remember this must go all the way back to the source of supply and in our boats the distance from the positive to the item and back again to the negative......usually twice the cable run distance

Current carying capacity of the wire, we calculate only on the crosss-sectional area of the conductors. The current carrying capacity of the wire as listed will be at 20 or 25 deg celcius, and in open air so if the wire is going somewhere hot like an engine bay or tied up in a bundle we have to consider that and go heavier

The voltage drop of the whole circuit, bassed on the wire size, the circuit distance and the current drawn. Once we get into heavier drawing items this will over ride our current carrying capacity selection.

Select circuit protection, this can be a bit more complicated, we want a fuse or breaker that will allow the item to operate, but will trip quickly under overload.
Certainly we want a breaker that will not allow the wiring to melt or burn.


Quite often our wire selections are restriced to one of a few choices that are available.

Remember we need to be talking in terms of cross sectional area (10mm2), in auto and marine electrical it is common to talk in terms of the nomonal outside diameter of the insulation which is most misleading.
6mm automotive wire is infact approximately 4.6mm2...and it gets worse in smaller sizes.
While we suposedly live in a metricated country, all the sizes and strandings of automotive & marine cable are derived from the US system and often sold in US guage.
OH hell I wish they would just call a spade a spade and tell us the cross sectional area in mm2.


as for the anchor winch.....unless you are running a long way....10mm2 twin would be a reasonable choice.....ya might get away with 6mm2.....but I recon 25mm2 might be a bit of overkill...... but there is no harm in that.

6mm automotive twin (4.6mm2) would probaly work and may not burn, but it may be a very sad thing.........there is nothing more pitifull than the sound of a winch motor starved for voltage & current.

cheers

[timddo]

sorry mate, How about we calulate it all properly and work on max 5% voltage drop?

So the basic setup is 8.2m of cable in total? Can you tell us what winch it is so I can look up the actual specs on it?


As for cables, perhaps peterbo3 might be able to help you out if you can handle not using twin.

Andy was only kidding mate.

I will need to allow for a few bends so 8.5 meters in length. South pacific 710S ( baby anchor winch).

Great idea any, Peterbo3 should have all the cables.

thanks

[finga]

In the civilised electrical world, we work on a rule of thumb of 10 amps per square mm of conductor.....with some corrections, for how and where the wire is used........and as Mr Wrigley says in the text...... often the limiting factor is the insulation not the wire.
Electricians worth their salt will know what current carrying capacities of wire are.
No rule of thumb should ever be involved. It's an exact science not rule of thumb.
The rule of thumb is what probably got Timdo's winch wired up in 2X2mm wires wired in parallel.
If in doubt consult the manual. One of which is the Olex cable manual.

If your wanting to figure out wire sizes in relation to current load and length work it out.
Work to 2-3 or up to 5% voltage drop and that will give you an answer.
I'm sorry but cable sizing does not work to a budget.
The cable size is either right or wrong. Once the cable size is found then you can shop around.

resistance = % x V x 1000
....................100 ........L x I
Please disregard the dots. It's the only way I could get the numbers and letters in roughly the right spot.

Now resistance is the resistance per 1000m figure you need to look for when you look up the table on page 96 of the Olex cable manual .
V is the voltage your working to
L is the length of cable
I is the current.
% is the percentage of voltage drop that is acceptable
So for Timdo:
voltage (V) of 12V
cable length (L) of say 8.5m
current (I) of 30A
% of say 5%

R= 5 x 12 x 1000
....100 .........8.5 x 30
R = 0.05 x 12 x 3.92
R = 2.35
Now that we have a number to work to we need a resistance that's lower then the number we have figured out.
So when we go to the table we see 6mm has a resistance per 1000m of 3.08 ohms. Not good as we're looking for 2.35
So we look at 10mm and we see it's got a resistance per 1000m of 1.83 ohms.
1.83 is lower then 2.35....we have a winner. Beauty :)
And then if we look at 16mm we see the figure of 1.15....better still and if you do the sums for a 3% voltage drop then you'll need the 16mm as you have to work to a calculated maximum resistance per 1000m of 1.41.

If you allow for things like heat build up and bad connections I'd be seriously considering the 16mm....especially as I personally like a 2-3% drop max on 12V dc.

[timddo]

guys

i have sourced some 16mm square 2 twin from springers at $15.40 a meter by 8.5 gives me $130. ( tinned too) I suppose it's worth it not to pull the anchor up by hand.

10mm square would be $93 or so.

Now the bloody connectors are only 6mm studs

[TheRealAndy]

Ok, so that unit only draws 12A for a maximum of 15minutes.

Given those values, 6mm2 is ample, 10mm2 is ideal. Votlage drop will be 0.6V (5.3%) and 0.37V(3.1%) respectivly.

Using the standard 8B&S cable from Bias and whitworths etc, Voltage Drop is 0.42V (3.5%)


So, if its wired with 6mm2 (not 6mm outer diameter) then I would leave it as is. If its smaller than that and you insist on rewiring, then go hit up peterbo3 for some 10mm2 cable and use that.


Now, do you need lugs?;D

[TheRealAndy]

Posted before I read your response. Dont buy from springers, PM peterbo3.

I should have plenty of crimps to suit 10mm2 cable with 6mm stud. Will check tonight. I also have a tool for crimping them properly

[MattChew]

Posted before I read your response. Dont buy from springers, PM peterbo3.

I should have plenty of crimps to suit 10mm2 cable with 6mm stud. Will check tonight. I also have a tool for crimping them properly

If you need some Tinned solder and a Butane torch just send me a pm.
Ta
Matt

[finga]

Ok, so that unit only draws 12A for a maximum of 15minutes.
Well done Andy for actually finding out what current is drawn.
I was working to the 30A as it was mentioned somewhere before.

It just goes to show to find out all the details forehand....and assume nothing.

[tigermullet]

Looks like there will be a re-wiring job for me. The chandlers advise that their 6mm single wire (tinned) is actually 4.59mm2 which means my wiring is way too light.

[oldboot]

OK.... cable rating is an exact science..... but it all works arround the base of 10 amps per square mm.......at least thats what all the tables I have in both manufacturers catalogues and the wiring rules work out to.....with correction factors and allowances .

At least if you understand that you have a clue if the figures you are seeing are in the ball park of being correct.

cheers

[finga]

OK.... cable rating is an exact science..... but it all works arround the base of 10 amps per square mm.......at least thats what all the tables I have in both manufacturers catalogues and the wiring rules work out to.....with correction factors and allowances .

At least if you understand that you have a clue if the figures you are seeing are in the ball park of being correct.

cheers
So this winch is rated at 12A.
So a 1.5mm cable will do the job??
Should be plenty seeing 1.5mm is good for 15A apparently.
Oh bugger it. Allow for some correction factors and allowances and go 2.5mm.
Now that's gotta be good as 2.5mm is good for 25A and we only need 12A.
That's over 100% allowances on the 10A per mm rule of thumb....and still wrong

Not even close to be in the ball park of been right according to what Andy has worked out.

I hate rule of thumbs....

[timddo]

So this winch is rated at 12A.
So a 1.5mm cable will do the job??
Should be plenty seeing 1.5mm is good for 15A apparently.
Oh bugger it. Allow for some correction factors and allowances and go 2.5mm.
Now that's gotta be good as 2.5mm is good for 25A and we only need 12A.
That's over 100% allowances on the 10A per mm rule of thumb....and still wrong

Not even close to be in the ball park of been right according to what Andy has worked out.

I hate rule of thumbs....

Ok. The website says 8 awg Min. Current Draw 12Am typical

So i'm getting 10mm2.

Problem solved.

Finga 1.5mm2 -- come on dude???? Websites says 8 AWG Min::)

[tigermullet]

I don't think Finga actually meant that!

This is been a beneficial education for me - not that I know much but am beginning to see the light.

Is this a great forum or what?

[deckie]

But But But..how much does it REALLY draw when the pick is stuck solid, you're pointing into 20knots of breeze, and you're in a bad mood coz of the gutless winch ;D. Plus it isnt brand new anymore.

[tigermullet]

I wouldn't know, except that winches are not meant to be used in that manner. Boat power should be used to take the boat to above the anchor and to break it free. This is where a nifty little chain stopper comes in handy by taking the load off the winch at rest and on retrieval.

[finga]

Ok. The website says 8 awg Min. Current Draw 12Am typical

So i'm getting 10mm2.

Problem solved.

Finga 1.5mm2 -- come on dude???? Websites says 8 AWG Min::)
Well it is good enough according to the rule of the thumb....:):)
12A load by the anchor and 1mm is good for 10A.....apparently...so according to the rule of the thumb you only need 1.2mm but they don't make that so 1.5mm should be the go...according to the rule of the thumb. :-?


Tigermullet has made a really, truly excellent point about the use of anchor winches too.
So between Andy and Tigermullet this anchor winch caper is solvered.
Well done chaps
http://smileys.on-my-web.com/repository/Respect/bravo-009.gif

[tigermullet]

Shit! - I'm famous.

[oldboot]

So this winch is rated at 12A.
So a 1.5mm cable will do the job??
Should be plenty seeing 1.5mm is good for 15A apparently.
Oh bugger it. Allow for some correction factors and allowances and go 2.5mm.
Now that's gotta be good as 2.5mm is good for 25A and we only need 12A.
That's over 100% allowances on the 10A per mm rule of thumb....and still wrong

Not even close to be in the ball park of been right according to what Andy has worked out.

I hate rule of thumbs....


I don't know what your problem is but.

1.5mm2 cable will certainly carry 12 amps

Is not, 15 amp mains flex 1.5mm2 or 30/0.25mm cable.
Is not, 10 amp mains flex 1mm2 or 32/0.20mm cable....and on and on

If we step to 20 amp mains flex at 2.5mm2 and 50/0.25mm we see an example of a correction.

how about some automotive examples
my Tycab catalogue reveals

4mm automotive 1.8mm2 to be rated at 15 amps ball park with the 10 amp/mm2 rule....possibly a derating for temperature that may be found in cars......the americans would push it harder

#8 AWG at 7.91mm2 rated at 85 amps..still in the ball park, probaly an derating for temperature and an uprating for the intermittent starting duty.

The 10 amps per square mm is unavoidable........and a usefull reference for confirming the qouted current carrying capacity

If i saw a reference that rated 4mm automotive at 25 amps I would be sus....but that is arround the ballpark that the american automotive types would rate 14 guage cable in certain situations.



Current carrying capaity of the wire is only a small part of the selection of a cable.

certainly if you connect a 12 amp load with 1.5mm cable of any length......the cable will carry the load.......but the installation my not be appropriate, the voltage drop may be excessive and the device may not work properly.

But i think i covered the process pretty well in my previous thread.

cheers

[TheRealAndy]

I have seen those current capcities in the tycab cataloge, listed as a JASE standard. I have also seen a yanky version from the NEC standard. To be honest, its pretty stupid of them to list those capacities when its near impossible to understand how they come to such values. Without seeing the standard, I cant comment. The tycab catalog also says "** AMP RATING: TO JASO D609 derating factors apply" whatever that is supposed to mean. Hence the reason I said earlier I dont get the automotive industry. What tycab do, is they supply nominal area, resistance and insulation grade, and that is what sparkies legally have to use here in australia.

I work from the Australian Standards. I have only ever been exposed to AS, and I did my aprenticeship using AS. I personally only have a copy of AS3000, but the nominal cable sizes are listed in AS3008, which I dont have. If anyone has a PDF copy of AS3008 I would like to be your friend;D

[Spaniard_King]

Too Many Scientist on this website

6mm twincore if you want it to last a few years.. 8mm if you want it to last 5-10 if terminated correctly!

I buy my lugs from CNW and they are double crimped with hydraulic crimper!

[TheRealAndy]

Too Many Scientist on this website

6mm twincore if you want it to last a few years.. 8mm if you want it to last 5-10 if terminated correctly!

I buy my lugs from CNW and they are double crimped with hydraulic crimper!

I wouldn't say scientists, but def 2 sparkies who did this shit for a crust :P

[Spaniard_King]

Yep :) :) :)

The problem is not with the cabling as timmdo will agree, the switching gear and circuit breakers they supply are a joke..., last one I did had 4mm screw to terminate the cabling to the switch gear :P absolute joke when the instructions ask for 8mm cabling.. whpping big cabling to a small screw... stupid

[TheRealAndy]

Yep :) :) :)

The problem is not with the cabling as timmdo will agree, the switching gear and circuit breakers they supply are a joke..., last one I did had 4mm screw to terminate the cabling to the switch gear :P absolute joke when the instructions ask for 8mm cabling.. whpping big cabling to a small screw... stupid

Cant agree more, I am going through the same process at the moment whilst rewiring my new boat.

Problem is, you can use small cables/bolts/lugs for short distances. But it all changes when you start adding long cable runs. Draw to much current through a small cable over long distance and you get heat. Heat increases resistance which in turn further increases heat.

[tigermullet]

Just when I thought I was on the right track!

But Garry is correct. My 6mm wiring is thicker than the screws attaching it to the switch gear and circuit breaker. There's not a great deal of surface contact area either.

Might leave things as they are - the winch seems to be working just fine, retrieving 20 metres of 8mm chain and a 27 lb sand anchor in 50 seconds.

[finga]

I don't know what your problem is but.

1.5mm2 cable will certainly carry 12 amps

Is not, 15 amp mains flex 1.5mm2 or 30/0.25mm cable.
Is not, 10 amp mains flex 1mm2 or 32/0.20mm cable....and on and on

If we step to 20 amp mains flex at 2.5mm2 and 50/0.25mm we see an example of a correction.

Yep. I have a problem. I hate rule of thumbs. Plain and simple
Actually I should like them because they made me lots of money during my working career.
Yes, 1.5mm flex will carry 12A. But for how far?
Yes, 1.5mm flex will carry 15A. But for how far?
Yes, 1.0mm flex will carry 10A. But for how far?
The key component in those figures is the operating voltage.
These figures, as you've stated, as been mains flex or working at a voltage of at least 240V ac.
This problem involves 12v dc
Now go back to the resistance calculations for this winch and do the 12A load and see the difference in cable sizes needed when you go from 12Vdc to 240V ac when the distance of a measly 8.5m is involved.
What's the result of those calculations?.
The result is exactly why Australia does not distribute it's power at 12V dc but at 240/415 or higher ac voltages and why a lot of heavy vehicles use 24V dc.
I won't delve into the differences between AC and DC here.

how about some automotive examples
my Tycab catalogue reveals

4mm automotive 1.8mm2 to be rated at 15 amps ball park with the 10 amp/mm2 rule....possibly a derating for temperature that may be found in cars......the americans would push it harder
Yep. Goodo. But how far will 1.8mm push 15A at 12v dc with an acceptable voltage drop of 5%?? (I prefer 2-3% but I'm a bit fussy)
Around the 4m mark I reckon if you only want 5% voltage drop.
That's assuming 1.8mm has a DC resistance of around 10 ohm/kilometer @20 degrees C.
Even for 2.5mm with a current of 15A with 5% voltage drop will only give you a working distance of 5.23m
So that rule of thumb of 1.8mm carrying 15A is only good if you wanting an acceptable voltage drop of 5% and want to work on a Peel 50 car that's 1.4m in length.
#8 AWG at 7.91mm2 rated at 85 amps..still in the ball park, probaly an derating for temperature and an uprating for the intermittent starting duty.

The 10 amps per square mm is unavoidable........and a usefull reference for confirming the qouted current carrying capacity
For who?? I reckon those too lazy to work out cable sizing in the correct manner.

If i saw a reference that rated 4mm automotive at 25 amps I would be sus....but that is arround the ballpark that the american automotive types would rate 14 guage cable in certain situations.
I would also be suss. I would laugh....and out loud too...and then throw the book in the bin


Current carrying capaity of the wire is only a small part of the selection of a cable.
Well why not cover them instead of ball park figures. They help no-one and give people the wrong impression.
That was proved with the 1.8mm example. It's only good for 15A for a distance of about 4m if you only want a 5% voltage drop.

certainly if you connect a 12 amp load with 1.5mm cable of any length......the cable will carry the load.......but the installation my not be appropriate, the voltage drop may be excessive and the device may not work properly.
Oh yes. But, and I quote:"It's the details, those little details, that make the difference".


But i think i covered the process pretty well in my previous thread.

cheers

I have a paper copy of 3008 here somewhere. I'll just have to find it.

[tigermullet]

Obviously, I only thought I was confused before. Now, I really am. It's back to the plan to re-wire the lot just to be on the safe side.

[Captain Seaweed]

I have a paper copy of 3008 here somewhere. I'll just have to find it.


I just pulled out my 3008.1-1989 to scan and post but started sneezing at the dust coming out of it!

[TheRealAndy]

Obviously, I only thought I was confused before. Now, I really am. It's back to the plan to re-wire the lot just to be on the safe side.

Lol, I think we should get Mod5 to lock this thread!!

Honestly, if its working, doing the job and not popping fuses or melting wires then why change it? Next time you winch in 20m of chain grab a hold of the wires, if you cant touch them then maybe you should upgrade:P

Why did you want to change the wiring anyway?

[tigermullet]

Why did I want to change the wiring? This thread! I bought 6mm (single wires not twin core) because I thought it was thick enough and the chandlery didn't have 8mm. After reading the first couple of posts on this thread I began to get the idea I had made a mistake and have realized just how complicated this whole business of wiring really is. Well, to me anyway.

Thanks for the tip about grabbing the wires after winching. I've already given it a go but cannot say why I did it. The wires were cool = no detectable heat. I'll try it again after giving the winch even more work. I guess, my main concern is with voltage drop and burning out the winch motor. I wasn't worried prior to this. Ignorance is bliss.

[finga]

I just pulled out my 3008.1-1989 to scan and post but started sneezing at the dust coming out of it!
You would have been busy. 130 odd pages now.

[TheRealAndy]

Why did I want to change the wiring? This thread! I bought 6mm (single wires not twin core) because I thought it was thick enough and the chandlery didn't have 8mm. After reading the first couple of posts on this thread I began to get the idea I had made a mistake and have realized just how complicated this whole business of wiring really is. Well, to me anyway.

Thanks for the tip about grabbing the wires after winching. I've already given it a go but cannot say why I did it. The wires were cool = no detectable heat. I'll try it again after giving the winch even more work. I guess, my main concern is with voltage drop and burning out the winch motor. I wasn't worried prior to this. Ignorance is bliss.

BTW, grabbing the wires for a heat test is not the recommended method of ascertaining if the cables are of sufficient current capacity:P but it does work!!! I think most insulation used for cars and boats is rated to 90°C (need to look at AS3008 to be certain) so you should know before it gets to that!!!


The voltage drop wont cause your motor to burn out, it will just stop it from working as well.

[tigermullet]

The voltage drop wont cause your motor to burn out, it will just stop it from working as well.


You beauty! In that case all is well. The winch works as expected - or even better than hoped. I will leave things alone - after all I anchor in shallow water - generally not more than 4 to 5 metres and let out 15 metres of chain unless it gets very windy. Being lazy, I don't shift position - often staying in the one spot for a couple of days. The winch won't have to work hard.

Thanks again for your response and advice.

[TheRealAndy]

You beauty! In that case all is well. The winch works as expected - or even better than hoped. I will leave things alone - after all I anchor in shallow water - generally not more than 4 to 5 metres and let out 15 metres of chain unless it gets very windy. Being lazy, I don't shift position - often staying in the one spot for a couple of days. The winch won't have to work hard.

Thanks again for your response and advice.


No problem.

I can beleive this thread actually managed to make 5 pages!

[timddo]

i found this formula to calculate voltage drop.

Formula 2 X L X A X I divided by cable sixe in mm2 ..

L = Length of cable , A = Amps being carried and I is the resistance of the cable ( Copper is 0.017 , Steel is 0.028 ) ...

So in theory i will get a voltage drop of .35 volts. ( using 8.5 meters of cable and 10mm2).

This has been a great learning curve. Andy's probably already covered this though

[oldboot]

Um.. sorry to be picky..... but 1.5mm2 or 15 amp flex will carry 15 amps regardless of voltage.
and more importantly

It will carry 15 amps the same distance with the same voltage drop regardless of the supply voltage involved.

How much voltage drop is acceptable is a whole different decision.
A matter which has been discussed, and i cant remember argueing with.


Remember too
in the world of DC, outside of the building industry, there are very few standards and all most without exception they are unenforceable.

There may be some legal requirements for boats under survey, but privately registered pleasure boats........ nup.

and if you think 20 to 25 amps on a 1.8mm2 wire is a joke..... check out the wiring in your almost any car.......you will die laughing.

Most local manufacturers dont even make 18 or 20 guage automotive cable..... but you will find it in your cars and mine and operating well over the 10 amps/mm2 and at quite high voltage drops.

measure the voltage at your stop lights..especilay with a trailer attached.....what a laugh.


cheers

[TheRealAndy]

Um.. sorry to be picky..... but 1.5mm2 or 15 amp flex will carry 15 amps regardless of voltage.
and more importantly

It will carry 15 amps the same distance with the same voltage drop regardless of the voltage involved.

How much voltage drop is acceptable is a whole different decision.
A matter which has been discussed, and i cant remember argueing with.


Remember too
in the world of DC, outside of the building industry, there are very few standards and all most without exception they are unenforceable.

There may be some legal requirements for boats under survey, but privately registered pleasure boats........ nup.

and if you think 20 to 25 amps on a 1.8mm2 wire is a joke..... check out the wiring in your almost any car.......you will die laughing.

Most local manufacturers dont even make 18 or 20 guage automotive cable..... but you will find it in your cars and mine and operating well over the 10 amps/mm2 and at quite high voltage drops.

measure the voltage at your stop lights..especilay with a trailer attached.....what a laugh.


cheers

Seriously, have a good think about what you just said.

[oldboot]

It has just occured to me that perhaps this whole thing is being "over thunk".

Phaps it is on one hand, but on the other hand some things are being overlooked.

In the world of the "Full Ticket Sparkie", the supply voltage is more or less fixed, and there is an expectation of no more than 10% voltage drop across the whole system..or something like that.

Now we move across to a boat or car with a "12 volt system".

If that vehicle has been sitting for some time without the motor running the supply voltage will be arround 12 to 12.5 volts, but as soon as we start the engine and run it for a while our supply voltage will come up to arround 13.5 to 15 volts depending on the charging system.

Then we start cranking some sort of heavy motor ( winch, starter motor).
If the engine isnt running the battery will be loaded down and the terminal voltage with drop ( how far good question).....10 volts would be not unreasonable engine cranking a car or 4 stroke inboard.

So how much battery terminal voltage drop will a winch cause.
In a car the alternator will be able to supply 40 amps pluss, but many of our outboards will only supply 8-15 amps..how much will that help.

so in short even without the voltage drop in the wires we may have dropped several volts.

So we need to think about heavier cables that we would on a fixed supply.

I can see how some of the "uneducated" would say FK the maths i'll just put the heaviest cable in that I can manage.....and I would say "I can not argue with that"

now a sad story
I went fishin with a mate, he had an average 16 foot runabout with 60Hp on the tail...all was great, a snoger bream caught..BUT when we got back to the ramp.

He trots out this cable with jumper clips to hook his winch up to his car battery.

anyway he starts pulling the boat on....as the load came on the progress stopped

so he starts up the car, and I have to keep the revs up while he winches on.....OH the sad and mournfull sound of the winch:'( , even then the boat barely got on.

now the cable was 6mm automotive twin and arround 6 meters of it.....12m cable run.

combine the voltage drop in the battery and the voltage drop in the cable and the resistance in the clips and there was a real problem.

I recon it mught have cranked on with a good heavy cable and a better connection and no assistance from the alternator...maybe.

But the voltage drop in the cable was not the only issue.

So are the voltage drop figures in the building industry standards suitable.

There is very rarely any harm in using heavier cable.

cheers

[oldboot]

Seriously, have a good think about what you just said.

Um yeh I have.

voltage only appears in the volatge drop equasion as an output.

A given current, in a given wire, will always result in the same voltage droped and that is a fact.

basic ohms law.

The supply voltage is irrelivent in calculating the voltage dropped.

How much voltage drop is acceptable is a completly seperate issue, and an "engineeing decision" and not a fact.


cheers

[finga]

It has just occured to me that perhaps this whole thing is being "over thunk".
Sparky's worth their salt have to think otherwise things burn and people die

Phaps it is on one hand, but on the other hand some things are being overlooked.

In the world of the "Full Ticket Sparkie", the supply voltage is more or less fixed, and there is an expectation of no more than 10% voltage drop across the whole system..or something like that.
Seriously, have a good think about what you just said

Now we move across to a boat or car with a "12 volt system".
But the voltage drop in the cable was not the only issue.
True BUT it's on top of the hit parade.
It's a main issue as well as current carrying capacity and short circuit temperature rise.

A couple of quotes from AS 3008: Electrical Installations - Selection of cables.

1.1 SCOPE
This Standard sets out a method for cable selection for those types of electrical cables and
methods of installation that are in common use at working voltages up to and including
0.6/1 kV at 50 Hz a.c.
Three criteria are given for cable selection, as follows:
(a) Current-carrying capacity.
(b) Voltage drop.
(c) Short-circuit temperature rise.
and
2.2 SELECTION PROCESS
The following three main factors influence the selection of a particular cable to satisfy the circuit requirements:
(a) Current-carrying capacity Dependent upon the method of installation and the presence of external influences, such as thermal insulation, which restrict the operating temperature of the cable.
(b) Voltage drop Dependent upon the impedance of the cable, the magnitude of the load current and the load power factor.
(c) Short-circuit temperature limit Dependent upon energy produced during the
short-circuit condition.
The minimum cable size will be the smallest cable that satisfies the three requirements.

So as far as Australian Standards are concerned voltage drop is a big thing and one well worth considering.


So are the voltage drop figures in the building industry standards suitable.
Why aren't they suitable. A lot of stuff wired in the building industry is DC and around the 12-24V. And what better standard is there to use other then one as authoritative as Australian/New Zealand Standards.
You could also consider AS 1125:2001 for cable selection
There is very rarely any harm in using heavier cable.
Cost would be a big harm in a lot of circumstances.

cheers

Full Ticket Sparkie's have to think. They have to think about a lot of different things before a cable can be selected or the installation method of the cable is selected.
Rules of thumb do not work.
They never have and never will.
That's why it takes a fair period of time to do an apprenticeship.

[finga]

Um yeh I have.

voltage only appears in the volatge drop equasion as an output.

A given current, in a given wire, will always result in the same voltage droped and that is a fact.

basic ohms law.

The supply voltage is irrelivent in calculating the voltage dropped.

How much voltage drop is acceptable is a completly seperate issue, and an "engineeing decision" and not a fact.


cheers
Voltage drop for those in the trade is considered as a percentage of the supply voltage...never at a nominal voltage of say 7V
What percentage of the supply voltage is dropped if the calculated or measured Vd is say 7V when the supply voltage is 12V and then 240V??
"How much voltage drop is acceptable is a completly seperate issue, and an "engineeing decision" and not a fact".
Oh dear. Australian Standards are pretty factual. And a maximum of 5% would be about right.
I should know. I've issued a lot of defect notices with non compliance from AS 3000 and AS 3008 with a fair whack of them concerning cable selection.
I reckon Australian and New Zealand Standards would agree with their publications been factual.
Engineers have to work to minimum standards...what would they be??

[oldboot]

Full Ticket Sparkie's have to think. They have to think about a lot of different things before a cable can be selected or the installation method of the cable is selected.
Rules of thumb do not work.
They never have and never will.
That's why it takes a fair period of time to do an apprenticeship.

Um.....4 years and a certificate 3 competency.......just like a plumber.....or carpenter.......yeh I served a 4 year apprenticship too.

Funny I don't know how but the regulators seem to think plumbing is more dangerous than electricity......that is why the still inspect plumbers work... but lets not go there.

I don't question how much thinkin' an electrician should be doing.

What I am questioning is if the preconceptions of the 240V world translate across to the 12 volt world.

Yeh I do think about what I have posted......think on it, a supply voltage that is legesated to a standard, and should not ever vary too far beyond that standard in a correct instalation in normal operation.

A 12 volt automotive system supply could be as low as 8 volts and as high as 15 volts and not be considered faulty that is a variation of near 20%..even that not guaranteed by standard or legeslation.

In a normal low charge cranking situation the terminal voltage on a starter motor may be as low as 6 volts ( half nomonal supply) and still start the car...just.. the ignition system has to work and the engine management too.......and the whole system will probaly recover without harm

If we have 120 Volts on a 240V fridge motor we are certainly out of spec and have a real problem.


As far as the building standarsd being relivent to auto electrics and boats.

The wire table and the procedured will certainly apply, but they exist without the standard anyway, along with a whole pile of engineering expectations and work method requirements.

DC wiring systems in the building industry would be a very very small persentage, barely worth a chapter in AS300. It devotes more space to flexible cords.

Most of the larger institutions that work with extensivly DC have their own standards and practices that are far stricter than the building electrical standards.

when we are expecting large fluctuations in the supply voltage perhaps we should be considering much lower acceptable voltage drops in cables AND other improvements in our work methods and expectations to compensate.

So if 10% voltage drop is what is acceptable AND we have lost that with the battery sagging.....where does that leave the voltage drop in our cable.

ya see where I am going.

As far as cost being an issue......in the building industry, cable runs are relativly long and there is always cost preasure........another 50cents per meter could bust the budget......so many of the methods in the building electrical industry are cost motivated.
Interesting plumbers demand a higher labour rate in the market than electricians..... but who wants to work in S.... all day

In a boat or car we are mostly talking cable runs in the single digits....an extra couple of bucks a meter is not the problem here that it would be in the building trade.

SO $8 per meter V's $12 per meter over a 5 meter run......if it makes my anchor winch on my $35 000 boat work better...who cares..even $8 a meter V's $20 a meter.....for one of the most important things on a $35 000 boat..its a no brainer.


I ask you not to get upset about what I say but to think about the implications.

There are different considerations crossing over the disciplines.

cheers

[oldboot]

Voltage drop for those in the trade is considered as a percentage of the supply voltage...never at a nominal voltage of say 7V
What percentage of the supply voltage is dropped if the calculated or measured Vd is say 7V when the supply voltage is 12V and then 240V??
"How much voltage drop is acceptable is a completly seperate issue, and an "engineeing decision" and not a fact".
Oh dear. Australian Standards are pretty factual. And a maximum of 5% would be about right.
I should know. I've issued a lot of defect notices with non compliance from AS 3000 and AS 3008 with a fair whack of them concerning cable selection.
I reckon Australian and New Zealand Standards would agree with their publications been factual.
Engineers have to work to minimum standards...what would they be??

Remember the vast majority of any standard represent "wise engineering decisions" bassed on carefull consideration in context not facts.

I do understand but when the supply voltage is small and variable, the persentage is nothing more than a arbitary figure....an engineering decision or "a rule of thumb" if you like.....

combine the permissable supply variation with the acceptable voltage drop and 10% variation is more like it than 5%.

Like it or not AS 3000 is full of rules of thumb, possibly not recognised because they have been formalised, but rules of thumb all the same.

Remember not only the supply voltage but the supply tolerance of appliances and equipment on 240V mains is regulated by standard and legeslated by law......the system is pretty damn good.....if other areas were as sensibly regulated, life would be so much easier for so many of us.

In the 12 volt word, the supply tolerances of different items can vary wildly and there is no standard to regulate it.

If we are to do the "whole job", my maths we need to know what the supply tolerance is of that item.

Some "12 volt" items may run happliy at 5 or 6 volts, others may exhibit problems at 11.5, yet others will not run at best efficency with less than 13 volts..and there is seemingly no rhyme or reasn to it.

It occurs to me the best approach is to, do the best you can and run the heaviest cable that is practical and within reason...a philosophy that would send you broke in the building industry.
And it seem this works very well for those "uneducated" and willing to spend a little extra.

And in truth when we consider available wire sizes....even if we do the maths we probaly end up no different.

cheers

[finga]

Um.....4 years and a certificate 3 competency.......just like a plumber.....or carpenter.......yeh I served a 4 year apprenticship too.
In what??

What I am questioning is if the preconceptions of the 240V world translate across to the 12 volt world.
They do. Electrical theory is electrical theory and standards are standards.


A 12 volt automotive system supply could be as low as 8 volts and as high as 15 volts and not be considered faulty that is a variation of near 20%..even that not guaranteed by standard or legeslation.
8V dc is OK in the auto industry??

In a normal low charge cranking situation the terminal voltage on a starter motor may be as low as 6 volts ( half nomonal supply) and still start the car...just.. the ignition system has to work and the engine management too.......and the whole system will probaly recover without harm
You reckon??

As far as the building standarsd being relivent to auto electrics and boats.

The wire table and the procedured will certainly apply, but they exist without the standard anyway, along with a whole pile of engineering expectations and work method requirements.

DC wiring systems in the building industry would be a very very small persentage, barely worth a chapter in AS300. It devotes more space to flexible cords.
I dunno about that. Solar power seems to be catching on and I thought that was DC...as well as dc controlling of appliances and then there's dc lighting and ..... the list goes on. That's why there are tables in AS 3000 and 3008 that involve dc.
The installation of dc cabling should be regarded along the same lines as ac cabling.
DC is dealt with throughout both publications.
There are no specific chapters dealing with DC but in AS 3000:2007 there are a few clauses. Those clauses start at 7.5 and the title is Extra-Low Voltage Electrical Installations.
So you kinda get an idea of what the chapter is about.
Now clause 7.5.7 deals entirely with voltage drop and refers the reader to AS 3008.

Most of the larger institutions that work with extensivly DC have their own standards and practices that are far stricter than the building electrical standards.
But those 'in house' standards would be merely extensions of the AS 3000 and 3008 standards.
when we are expecting large fluctuations in the supply voltage perhaps we should be considering much lower acceptable voltage drops in cables AND other improvements in our work methods and expectations to compensate.
Who's expecting large fluctuations in supply voltage. I don't want large fluctuations so design things a bit better.
If you do some reading supply voltages are required to be within certain guidelines


So if 10% voltage drop is what is acceptable AND we have lost that with the battery sagging.....where does that leave the voltage drop in our cable.
Try 5% maximum voltage drop. If the battery is not up to the job then a rethink is needed
ya see where I am going....going to the shop to get a better battery I reckon

As far as cost being an issue......in the building industry, cable runs are relativly long and there is always cost preasure........another 50cents per meter could bust the budget......so many of the methods in the building electrical industry are cost motivated.
Interesting plumbers demand a higher labour rate in the market than electricians..... but who wants to work in S.... all day
Who cares who earns what??
Who does a plumber call when his anchor winch doesn't work??
Is this relavent knowing who gets paid what to make an anchor winch work correctly??
In a boat or car we are mostly talking cable runs in the single digits....an extra couple of bucks a meter is not the problem here that it would be in the building trade.
Maybe in a Peel 50 or my 3.7m tinny they'd be single digits.

SO $8 per meter V's $12 per meter over a 5 meter run......if it makes my anchor winch on my $35 000 boat work better...who cares..even $8 a meter V's $20 a meter.....for one of the most important things on a $35 000 boat..its a no brainer.
If it's so important to get things right why work to a rule of thumb??
Isn't a $35,000 boat worth 3 minutes of sums??
So why not use $40/m cable where $8/m cable will be sufficient for the job??
It's only a 5 m run.
By rule of thumb we only needed a 1.5mm cable to run the anchor winch.
That's all it needed. 12A....rule of thumb 1mm per 10 A...= 1.5mm with room to spare.

I ask you not to get upset about what I say but to think about the implications.
Implication are people might read the rule of thumb and go...beauty. Electric motor...40A it says in the book so 4mm cable will do.
And then wonder why the electric blows up and warranty is declined.
Implications of rules of thumb can injure people or at the very least cause material damage.


There are different considerations crossing over the disciplines.
Sparks are sparks and poo is poo.

cheers
All this is because you said waaaaay back the rule of thumb is 1mm in cable cross sectional area will carry 10 A.
That has proved to be utter crap.
Andy would know better then anyone about dc that's used in industry and the importance of correct cable sizing and installation design. He's an instrument fitter as well as a sparky dude.
I'm merely a sparky dude with a few extra tickets.

[finga]

And in truth when we consider available wire sizes....even if we do the maths we probaly end up no different.

cheers
That would have to be the biggest heap of male bovine excrement I've read in ages.
Why did they bother writing all those books and making all those rules and working out all those tables.
They could have just said...refer to your left thumb and be done with it. It'll all work.
Lucky it's a rule of thumb and not a rule of hand as the left AND right hand rules are already taken thanks to Mr Fleming.

Rule of thumb....1mm of cable = 10A load...goodo.
Crap. Think of the implications or have a good disclaimer when making statements like that.

Like I said before. I should like rule of thumbs.
They made me lots of money doing repairs to those rules of thumb's and gave me lots of pleasure righting defect notices to those who used rules of thumb's.

[murf]

great post :) my head now hurts, so many past memories flooding back and I haven't touched the AS3000 in 10years, I just looked behind me and it is still on the shelf feeding the cockroaches ;D

I saved a couple of great little bits of this thread

cheers Murf

[deckie]

Someone pass the popcorn. This one's turned out entertaining.
Its no bloody wonder you sparkies have confused the crap out of us by giving us 10 different ways of saying the same thing with cables :P You cant agree on anything ;D

[peterbo3]

This table is from West Marine courtesy of Ancor Wire.
Could be helpful as it based on ABYC standards

[oldboot]

The simple an unavoidable fact is that you can not apply the requirements of ANY standard outside of its scope

The clue is the full name of AS3000, Electrical Installations- Buildings, structures and Premisis.

Boats and cars simply are not mentioned.

It has no standing in DC electrics in cars or boats.

These situations are "beyond its scope", both in practicality and legaly.

Now if ya want to start talking about AS3004- Electrical installations- marinas and pleasure craft at low voltage.......well go ahead... but even that is beyond scope because in the standards language low voltage is still 240V sort of stuff.

We are talking about extra low voltage.

There is the National Standard for Commercial Vessels, but even that is beyond scope, as these are recreational vessels.

AS1799 Small Pleasure boats code, would be as close as we can get.... but that can only be considered guidance as it is "superseeded"..and I do not believe it is called in legeslation.

There is huge step, between what is appropraite in Low voltage ( 240V ish) AC electrical and extra low voltage 12 & 24 voltish DC electrical installations.

Yes all the basic electrical math still works, and all the basic principles still work... and they exist without the standards

But a whole pile of assumptions central to design simply do not translate across.

The design of switch gear alone is massivly different, the types of motors and their design criteriour also are massivly different.

And ya have to face facts, even with in the scope of standards.....there are always situations that the standards simply do not account for

As far as what happens in a car or boat......just take out a fast responging DC volt meter, and measure a few things arround here and there and you will see what wide voltage variations occur in automotive style DC systems...What variations seem to be acceptableand functional?

With a flat and dying battery that would barely crank, as long as 1 cylinder would fire my old L300 would start, and all the 12 volt equipment would then operate just fine.....so what voltage barely cranks a 4 cylinder motor.....try it sometime


As far as DC in AS3000...you are right DC does not have its own chapeter.....but extra low voltage ( that is where or DC systems fit) has only a few pages....DC is hardly even mentioned.

As far as the standards and requirements in large institutional DC systems.......these guys have had standards and manuals on procedures before standards even thaught about the matter.....and when standards do end up issueing a standard..these are the guys who would be on the working group.

And as we have seen High current DC does not even get a mention in AS3000 so how would it be an extension.

As far as this solar boom.....well standards always have and always will lag what is happening in industry.... but if not by now there certainly soon will be a seperate standard issued on solar installations, and you can bet your boots there will be some things that vastly differ from that happening "under the roof sheets"
to start with a 12 volt solar panel can have a terminal voltage of from nutthin to 20 volts ish.

The bottom line is we do not need any standard to do this job properly.
we need Ohms law and very little else.

V (voltage drop)= I (the current drawn in the circuit) x R (the resistance in the cable).....this can be found in the manufacturers document or measured from the cable.

The sticking point is how much voltage drop is accpetable.....and we can not rely on an arbitary persentage from an irrelivent context.

we need to either ask the manufacture, or test the item and see what it will tolerate.

Remember that some DC motors will work very well over a huge voltage range.

And in fact some DC motors are designed arround there being a considerable variance in supply voltage...this is not true of most 240V motors.

So what would be interesting would be to find out how much better our friend with the winch wired in 6mm automotive would find things wired in heavier cable.

Juts like pulling out of context and critising my rule of thumb for cable capaity only.....working out the voltage drop in a cable is not the whole job, in fact is is only 1/3 of the job.

we need to allow for
Variation in the supply voltage.
Voltage tolerance of the equipment
and
Cable current capaity.
and
Voltage drop in the cable.


The first two are specified by law in the 240V electrical world, but not in DC land.

Our best and simpleset answer is to consult the manufacturer of the winch and consider their opinion.....then maybe go a little heavier.....it never hurts.

AS far as my occupation and training.
I trained as a telecommunications technician, back when we did everything from the phone lines with factions of a volt to the huge batteries..... hell I even trained on belt message conveyor systems and pnumatic tube systems......and at the time some of the AC electrical work because we were commonwealth staff working on commonwealth property and beyond state durisdiction.....(the electricains always hated this)

Since then ( about 20 years) in have worked mainly in the entertainment industry contarcting sound lighting and AV installations, but I have worked on a very wide variety of other equipment......
I hold several certificate 3 competencies, 1 certicficate 4 competency, an open communication cabler licence, a restriced electrical licence and a restricted contractors ticket, among other things.... but none of that changes the facts.

One thing that is constant however.....is sparkies trying to tell us that their rules and standards and methods apply to work that it simply does not.

I do not need a full electrical licence to run speaker cable, but plenty have tried to say so.

I have found a great deal of what I have and still do, sits on the verges of various standardards....and often people simply do not know what to do with it because regulations and standards are not clear or simply do not mention.

Believe me I am very enthusiastic about applying standards..but they all have their limits.

This issue has got far more complicated that it realy is...a simple matter of ohms law and asking a couple of questions of the manufacturer.
OR
Simply running the heaviest cable pratcical.

cheers

[finga]

There is an interesting little publication known as ISO 10133.
It's a little publication entitled Small craft — Electrical systems —Extra-low-voltage d.c. installations.

A few small clauses if I may:

4.5 All d.c. equipment shall function over a voltage range at the battery terminals as follows:
- for a 12 volt system: 10,5 V to 15,5 V;
- for a 24 volt system: 21 V to 31 V.
Exception: Where the circuit includes equipment requiring a higher minimum voltage, the specified minimum voltage shall be used in the calculation of the conductor size. See clause A.2.

4.6 The length and cross-sectional area of conductors in each circuit shall be such that the calculated voltage drop shall not exceed 10 % of the nominal battery voltage for any appliance, when every appliance in the circuit is switched on at full load.

7.5 Conductors shall have minimum dimensions in accordance with Table A.1, or the conductor manufacturer's rated current-carrying capacity, based on the load to be supplied and allowable voltage drop for the load to be carried. Conductors in voltage-critical circuits, such as starter motor circuits, navigation-light circuits and ventilation blower circuits, whose output may vary with system voltage, shall be sized in compliance with the component manufacturer's requirements.

Annex A in ISO 10133 is a particularly interesting annex.
It's title is:
Conductor Requirements in which there a part known as....and I quote:
Section A2:
As a guideline, the voltage drop E at load, in volts, may be calculated by the following formula:
E= (0.0164 X L X I) / S
where
S is the cross-sectional area of the conductor, in square millimetres;
I is the load current, in amperes;
L is the length, in metres, of the conductor from the positive power source to the electrical device and back
to the negative source connection.

So there we have an International Standard from the International Standard Organisation who basically tell us the acceptable battery voltage limits and how to work out voltage drop and a few other things as well.....where is a rule of thumb mentioned in this Internationally recognised Standard??
No friggin' where!!!
There's math involved and no rule of bloody thumb.

Important things from that standard.
Clause 4.5
All dc equipment installed in Small Craft must work at a minimum 10.5V in a 12v system unless specifically specified by the manufacturer....and that will only ever involve a HIGHER operating voltage...not lower.
So you would think things are generally not designed to work below a battery voltage of 10.5V....ever.
And you would also assume that battery voltage should not get below 10.5V for things to work correctly...and that's at full current load of the circuit/s.
Clause 4.6
Voltage drop is a maximum of 10% over the entire circuit route.
That is from battery positive terminal to negative battery terminal...at full load.
Clause 7.5
Conductors shall have minimum dimensions in accordance with Table A.1, or the conductor manufacturer's rated current-carrying capacity, based on the load to be supplied and allowable voltage drop for the load to be carried.
So using the data and methodology in Olex reference manual is an acceptable way of determining the level of voltage drop which can be used to work out the size of a suitable cable for a cable made by Olex.
AS 3008 would also be an acceptable reference as the tables are compiled from numerous sources and deliberation of learned people....and no rule of bloody thumb is mentioned in any of them

Conductors in voltage-critical circuits, such as starter motor circuits, navigation-light circuits and ventilation blower circuits, whose output may vary with system voltage, shall be sized in compliance with the component manufacturer's requirements.
So motor start circuits are defined as critical in an International Standard and CANNOT be looked at at any voltages below 10.5V dc ...period.
Who cares if a car starts on 6v or what voltage a battery slumps to??
If it's on a boat then something is wrong.

Small Craft are defined in an International Standard.
You could nearly include anchor winches as critical too I'd reckon...especially if you have a bad back.
And according to ISO 10133 cables shall (which to us means must) be sized in compliance with manufacturer's requirements of operating voltage.
So if the manufacturer says the winch works at 12V then it has to operate within 10% of 12V taking into account total voltage drop of full circuit load and full circuit length.

And then we get to Annex A and voltage drop.
(I think Timdo had something very similar to this in a previous post)
E= (0.0164 X L X I) / S

So for Timdo's winch
S= (0.0164 X L X I)/E
S= (0.0164 X 17 X 12)/1.2
S= 2.788mm which gives you a minimum cable size of 4mm to make the thing work to minimum requirements set out by International Standards where:
E=1.2 (been 10% of 12V)
L=17m (remember it's total circuit length from battery positive to battery negative)
I=12A
S=cross sectional area in mm
But there is also is also a bit in ISO 10133 called TABLE A1.
This table tells us the current rating of cables in relation to the temperature rating of it's insulation so you have to make sure that those requirements are met as well.
If the cable passes through an engine room there are also further de-rating factors associated with the extra heat of the engine room/compartment.

So there it is in black and white.
No rule of bloody thumb. No Ohm's law. No assumptions.

A couple of quotes if I may??
we need to allow for
Variation in the supply voltage.
Voltage tolerance of the equipment
and
Cable current capaity.
and
Voltage drop in the cable.


The first two are specified by law in the 240V electrical world, but not in DC land.
Think again.
ISO 10133 deals directly to the wiring of small craft and direct current. It is an International Standard. Australia recognises this standard.
And funnily enough ISO 10133 deals with the variables in basically the same manner as AS 3000 and AS 3008.....and bugger me if there is any mention of rule of thumb. I cannot read it anywhere......

And then there's this one:
I have found a great deal of what I have and still do, sits on the verges of various standardards....and often people simply do not know what to do with it because regulations and standards are not clear or simply do not mention.
You can't follow or reference the standards if you don't know what standards exists.

Oldboot has continually, and clearly, stated there are no standards for the wiring of small watercraft and has also clearly stated there are no standards for DC.
Well there is.
Simple and fact.
One that is of particular interest to the owners of small water craft is known as ISO 10133. It deals with boats and deals with DC
.....and no rule of that bloody friggin' thumb.

How did I know about ISO 10133??
I have a subscription to Australian Standards through SAI Global.
I did some checking and bugger me...a standard.
I thought I'd get more definitive information from that International Standard (ISO 10133) then I'd get from my thumb about some wires in a boat.
I looked at my thumb and asked it about wiring of small craft but all it said was..."You moron. You whacked me with a hammer the other day"
Not a mention from the black thumb about cable sizing for some reason.

But what would I know. I'm only a dumb sparky.


PS: too early for popcorn Deckie...

[Lucky_Phill]

It appears this thread has run it's course.

closure will happen shortly if no one has anything else to say !!!!


Cheers Phill

[tigermullet]

I'd like to see it keep on. Even though much of it is going over my head, I am learning a few things and found this to be one of the most interesting threads on this forum.

I see this as a discussion about a technical matter approached from different angles which has provided a valuable learning opportunity. I don't know how much more could be said but if and whatever it might be I will certainly read it.

I am very grateful this subject came up.

[theoldlegend]

Soooo, Finga,

I've carefully read all 80 posts on this thread and haven't understood a single one of them.

My question to you is: That coaxial cable you put in for the TV. Is it any good?

Please dont confuse me either. A single yes or no will be sufficient.


TOL

[TheRealAndy]

I gave up after we solved the problem! To many google experts.

[oldboot]

I am frustrated by my comments being taken out of context, and comments being atributed to me that I plainly did not make.

I have never stated that there are no standards applicable.

The issue remains that there are no standards that are enforceble under law in Australia that apply the small craft for recreational purposes.

In fact most of the marine electrical standards are framed around the larger craft to which they are legaly applicable

Also there is also nothing compelling manufacturers of equiupment for small recreational craft to comply with any electrical standard.


So from the various standards what is the accpetable voltage drop.....is it 10%, 5% or 3%.....and do any of those represent best practice or simply a minimum requirement......And what was the engineering reason behind these specified figures......or are they simply a rule of thumb?

And the truth is we do not need any standards to do this work in a proper and effective manner.

We need only ohms law and a little common sence.

As far AS3000....While it may be the central plank of the system of regulation for the grid connected AC electrical system.....it is not and never was intended to be some sort of universal electical holy grail......in fact out side of the grid connected electrical system and related matters it is intended to regulate....there is very little of it that applies to much at all.
AS3000 was never intended to be a how to book of all things electrical..especilly since the cover changed from yellow to blue and they took all the helpfull stuff out.

While the "standards" may specify a certain voltage window... the fact remains that a battery supplied system can and will on many ocasions operate outside of those specifications.

So there is nothing stopping a anchor winch manufacturer for instance offering a winch specificaly designed to cope with significant voltage drop and to operate on light cable.........this may be the case.......I do not know.

It certainly is the case of quite a lot of the LED lighting, some of the items offered will function to specification as low as 8 volts.

Finga it is plain and obvious that you never rettired from being an electrical inspector.

This remains a very simple matter, a choice of only a hand full of available cable choices.

And there are a number of ways to make a proper and workable choice.

You can do the maths if you like it is very simple. Ohms law

Or you can do as the "uneducated " do, very sucessfully and use the largest
practical cable.

Or if you like you can search the standards and go thru the specified rigmarole.

But there is no obligation legal or otherwise telling you how you must do it.

cheers

[finga]

I gave up after we solved the problem! To many google experts.
Your the smart one Andy.

I give up now.
You just can't tell some people.

There are standards and they are enforceable.
There are safe work practices to follow.
Just saying use the biggest cable you reckon is not an acceptable way to decide cable type/size to install anything especially something as critical as an anchor winch.
There are obligations for people to carry out work to ensure that proper work procedures are met and to ensure minimum standards of work practises are also met to ensure safety to both person and property and to ensure longevity and safe operation to the work they've done.
That's why learned people have written all these standards for plems like me to follow

There is no valid reason to question the minimum standards set out in the various standards because you think otherwise.
There is a key word there...and that is minimum.
These standards are the MINIMUM standard work should be done too...

There is a difference between are the standards enforceable and are they enforced.
Standards are enforceable but because they are not enforced is no reason to do what you think your common sense is better.

I have to admit I did not know of ISO 10133 until yesterday.
I have been curious about a specific wiring standards for small boats for a long time but had not found the relevant one.
I purposely went looking for it yesterday because I was just p!ssed and I knew there would be a standard that was directly applicable to small water craft....and there is.
I did learn something from reading that standard too.
I learnt of another way of working out voltage drop.
One that Timdo found much earlier in the piece.
Standards take all the if's and but's out of work practises.

And I don't really care if a Hiace will start at 6V or LED's are rated at 8V.
If something I have got down to 6 or 8V I'd reckon there's a problem somewhere.
I'd just fix the problem and get the voltage back to where it should be. Around the 12V + or - 10% so everything works the way it was designed to.

So if you want follow the minimum standard requirements set by many learned people and memorialised in International and Australian standards do it....or do what you think is common sense.
I don't care any more.

[oldboot]

Some one posted earlier on that you can never get two "electricians" to agree...Oh so true.... I have sat there on my duff waiting while they argued and waved various books at one another.

This is because even within the standards there are often several quite valid ways to achieving a compliant job and some tradesmen are simply blinkered into one method.

That is after it has been established which standard is appropriate if any.

The FACT remains there is absolutly no enforceability of any standard till it is called in legeslation.....someone has to pass a law to make a standard legaly binding.

Or some other person or orginisation has to specify compliance to a standard as a condition of a contract.....in larger boating that is often the insurer.
Often the big insurers have their own standards Lloyds for instance.

Standards are not laws.

If someone can show me legeslation that specifies a standard must be followed in relation to non commercial ,small craft I would very much like to know about it.

More and more, standards are not specifying procedures and work practices, the current philosophy is to specify the result and leaving the rest to the trade training.........and "fit for purpose" is the current mantra and there is a lot of stsndards compliant work out there that is not "fit for purpose".


If selecting a large enough cable by whatever means, results in an installtion "fit for purpose" and "compliant with standards" where required, it is perfectly acceptable, and 100% legal......it matters not how you got there.


cheers

[oldboot]

from Standards Australia web site.

Standards and the Law



Standards Australia is not part of government, we do not make laws or regulations.
Australian Standards are not legal documents but many, because of their rigour, are called up into legislation by government and become mandatory.
This is a decision made by elected governments, not Standards Australia.
Standards are also often incorporated into legal contracts.

Standards and Regulation
Standards are voluntary consensus documents that are developed by agreement and their application is by choice unless their use is mandated by government or called up in a contract.
Standards are one tool in a regulatory spectrum that may be applied by governments to provide a solution to a problem.
Depending on the issue, the optimal solution might be ‘no action’, or a non-regulatory solution like a publicity campaign, or self-regulation by means of a voluntary industry code or standard, or quasi-regulation such as a standard endorsed by government, or co-regulation such as a standard cross-referenced in a general or high-level regulation, or legislation.
Figure 1 illustrates the regulatory spectrum, identifying key “Choice Criteria” to guide selection of the appropriate regulatory tool. The basic principle is that risk assessment should be applied to an issue to identify the most appropriate solution.
The more risk attached to the behaviour or issue, the more government involvement is likely. In principle, progress to the right of the spectrum should be in response to increased risk to justify the increased cost and impact upon society. Standards are not always the most appropriate tool.

I think that covers it.

cheers

[FrogBat]

Hello all.

I don't post too much but this place does keep me amused.
This thread has been most entertaining to say the least and in particular the last post.
From what I have read the qualified electricians agree with each others means of getting to the answer of the question asked by Timddo. Even Timddo has answered his own question.
In this instance a question was asked and the answer was given.
It seems the only two people who are arguing are finga and oldboot.
One has to think why the other electricians have not entered into the debate in the later stages.

I have made a few observations.
Ones an electrician and the other has a restricted electricians license.
One is suggesting using the methods adopted by Australian and International Standards to achieve the answer to a question and the other is saying use to common sense and Ohm's law.
About the only thing else I have to add can be summed up in a simple picture.

[oldboot]

The only reason I have persisted this far is to defend my legal and moral right to use whatever method I wish that achieves a result that is both legal and "fit for purpose".

cheers

[finga]

I have a question.
How do you work out voltage drop Oldboot??
I've been through the whole shooting match and there is no where where you actually say how you work out voltage drops with ohm's law.
So how exactly do you do it?
Others have put up methods to work out voltage drop so maybe we can learn something else.
I'm always up to learning something new.

[oldboot]

Its there back in post #78

cheers

[finga]

You mean....
V (voltage drop)= I (the current drawn in the circuit) x R (the resistance in the cable).....this can be found in the manufacturers document or measured from the cable.
So how do you find out resistances if you don't like wading through manufacturers documentation or standards?
What's an acceptable voltage drop?

Is COLREG's legislated upon in Australia??

[TheRealAndy]

I cant beleive you 2 are still going!

Seriously, the thread was about what size wire to use, not about what he difference between standards and regulations is. I referenced the AS becuase they have lots of handy formula's which apply equally to 12 and 240V. The standards are relevant, becuase people have done the hard work for you to make stuff safe. Sure you dont have to use it, but your a mug if you dont.

Now as for using 1mm2 cable or whatever, do the maths. You soon figure out it current carry large amounts of current over distance because it will chatch on fire. This is basic ohms law. Do the maths, Power (W) = R * I².

Eventually the wire becomes so long, that its resistance will become the major part of the circuit. Then you will get a full 12V across the length of the cable and it will be the part of the circuit that will determine the current draw. NOt much use either if you want to run a motor.

So yes, you can use 1mm2 cable, but in the situation provided it was probably not a wise thing to do. Any discussion otherwise is just nitpicking and polluting thread, only confusing the person asking the original question.

Now, I am going to report this thread and ask it to be locked. If you want to argue standards, start a new thread relevent to the topic.

[timddo]

Common andy it's only 8:30am. I have another 7.6 hours of work left.

( As a matter related to this topic. I have replace the cable with 10mm2 solar cable). Winch even sounds different and works great.

Australian Stands are a guide. ETC. If you want to be a member or use ur name as part of that group. You will need to follow those standards.

[oldboot]

You mean....
V (voltage drop)= I (the current drawn in the circuit) x R (the resistance in the cable).....this can be found in the manufacturers document or measured from the cable.
So how do you find out resistances if you don't like wading through manufacturers documentation or standards?
What's an acceptable voltage drop?

Is COLREG's legislated upon in Australia??

All reasonable questions.

yes that is the formular

if you do not any have any manufacturers specs or standards available, the best you can do is measure a sample of the cable, either by measuring a preferably long sample or setting up a voltage drop test.

What is an acceptable voltage drop?.....My point exactly.
It will vary from item to item and situation to situation...... sometimes it will be a lower or higher figure than may be called in some standard.

sometimes it is simply a matter of geting it as low as you practicaly can.

Often the best option is to simply use the heaviest practical cable.

as far as the COLREGS, they most certainly are called in legeslation..I cant quote the national legeslation, but they are certainly called in the QLD acts.
And they are also mandated by international law.


As far as a given cable ( say 1mm2) not being able to carry its rated current over any length.
Unless said cable is coiled up or otherwise has it heat confined, a cable will not burn ( in fact it will perform to specification) if it is carrying less than its rated current regardless of length.

1mm2 cable 10 amps 100meters straight in open air, will run all day and all night, it might get a little warm but it wont burn......there will be an impractical amount of voltage drop at 12 voltsDC though... actually ya wont even get 10 amps out of it............ but if you ran arround 30 meters with 12 volts supply and the other end shorted........10 amps would flow and nothing would burn......bazare but true.

This is why lots of the people running large christmas lights displays run 15 to 18 volt transformers with 12 volt lamps......running realy heavy cables is simply impractical, so they bump up the supply voltage to compensate......might not be AS3000 but it is a reasonable enginered solution.....

cheers

[TheRealAndy]

Common andy it's only 8:30am. I have another 7.6 hours of work left.

( As a matter related to this topic. I have replace the cable with 10mm2 solar cable). Winch even sounds different and works great.

Australian Stands are a guide. ETC. If you want to be a member or use ur name as part of that group. You will need to follow those standards.

Lol. Yeah I got a few hours of work left. Passes the time when I wait for the computer to crunch the numbers!

I did the same on my boat for hydraulic pump for the keel. Upgraded from 6mm2 to 10mm2, and what a difference it made

[oldboot]

sereious question chaps.

both of you have just upgraded a cable run, with the no other changes, how did the voltage drop figures work out for both the old and the new cable runs.


This is an oportunity for some real science, you both plainly have noticable improvements.

Was the improvement as good or better than you expected?

cheers

[finga]

if you do not any have any manufacturers specs or standards available, the best you can do is measure a sample of the cable, either by measuring a preferably long sample or setting up a voltage drop test.s
Can this be expanded in terms of methodology including how measuring is done?
How is a voltage drop test conducted?

I am truly wanting to learn something.

[oldboot]

If I had an "unknown cable" I would prefereably get access to a long known length .
Like a 100m roll.......and use a low ohms meter like in my megger to measure the resistance of the whole roll and then work out the resistance per meter

This is very easy for lighter cable but gets harder and much less accurate as the cable gets larger and the available length gets shorter..

there are some options.
use a high accuracy low ohms meter a mate has a funky one thet even compensates for probe resistance and reads a couple of decmal places of ohms

I have seen but not used high current resistance meters that use several amps to improve accuracy.

get access to a bigger roll of cable for more length 1000m roll

do a loop on figure8 to double the length and improve accuracy

or set up a voltage drop type resistance test

Get a power supply and a load bung several amps down the cable and measure either the voltage across & current in the wire under test, or the voltages across the source, load and wire, assuming you have a known load resistance.

The heavier the cable the more current you need to get some accuracy.

Have I done the above.....yes some of them......I have measured the resistance of rolls of "mystery cable".......I have measured the resistance of rolls of cable to prove a point......and some times it has simply been quicker to probe a cable than find some specs.

I have done a voltage drop resistance test, but only in the class room and years ago.

Where do you get a full roll of cable..sometimes it is on hand, and I have had suppliers co-operate.

I have on some ocasions had to measure cable in installations where you know neither the cable length nor the cable spec.

As far as a voltage drop test.

If you have cable on hand or an existing situation.......you could do a voltage drop test.....simply run the existing set up under load or a contrived set up and measure the voltage both ends.

Of course most of this I would not do in a 240V or regulated cabling context.


I do have a reputation as a scrounger, and lots of undocumented stuff comes my way, and I do have a reputation of being able to make things work that others simply wont touch...so often I have no option but to test things to find out about them.

cheers

[Lucky_Phill]

circles........................................... .



LP