Inverter help

[frank100]

Re: Inverter help

Grand_Marlin,
Sorry to read that someone 'burst your bubble' re the perpetual thing. I personally like the idea !
FNQ, inverter in glass boat - a little dificult to connect the earth stake (especially on a high tide).
I'd be guessing that if the inverter is in a ventilated, dry (that could be difficult) location it should be OK.
Appliances that are double insulated should be no prob without earth, others I would be wary of using on a boat BUT ensure that the earth pin suppling the appliance is indeed connected to chassis. I would'nt connect the chassis to -ve battery supply since if it needed to be it would already be (internally). If not connected already it it do'nt need to be.
I think your main cocern would be to make sure the battery supply cables to the inverter can handle the current & the some, also make sure the connections to the battery and the inverter are secure & tight.(I like to spray DC connections with a "battery terminal coating" which ensures the connections stay dry & helps them stay tight .
Hope that helps

Frank

[oldboot]

Re: Inverter help

Bonding of the earth connections of generators and inverters is a very interesting philosophical question.

Some will argue that "technicaly" you should drive an earth stake and bond the earth terminal or case of said invertyer to " the greater mass of earth".

Personaly I have never seen it done
Not on a small inverter, not on a small generator, not on a larger 3 phase diesel generator.

Also I personlay believe it does not achieve a thing...........( correction...unless it is connected to some sort of wiring system or structure that is required to be aerthed)

consider this.

the generator or inverter ( I'll call it the supply device) provides an active ( live connection) a neutral connection and an earth connection.
What protection that supply device provides will be in relation to those terminals.

If the appliance used is double insulated and has no earth connection....there is nothing to argue.
If the appliance is matal cassed and has an earth connection, that earth connection will be connected to earth connection of the the supply device.

So what is missing, and what will connecting that device to the greater mass of earth achieve.......I do not believe a damn thing.

That is if the inverter is not connected to a permanently wiring system.... such as in a house......then there are plenty of issues.

The whole philosophy of how and why we earth things and why the neutral and the earth are both connected to the greater mass of earth is complex and associated with a whole wiring system that extends from the appliance back to the power station..........Now with a generator or inverter the vast majority of those considertions just arent there.

There is one important consideration though...... you now have a portable source of killing voltage.....An item that can be placed anywhere and is not controlled by rules and conventions that every other source of power is.
All other sources of 240V are controlled as to how and where they are installed.

The question of consiquence isn't should this item be earth bonded........the question is......Is it safe to use this device in this situation.

Would an electrician be permitted to install a power point where I plan to use this inverter............

The QLD government is so concerned about stand alone inverters that they are not permitted on building sites.

Most generators and inverters do not have the same sort of protection now mandatory in all installed 240V power....no earth leakage....som do not even have fuses or breakers in the 240V circuits.

Lots of people use thes things and think very little of it......we need to be thinking carefully before we fire up one of these things.

Don't get me wrong...... I own both a generator and an inverter......both are great things and with a little thaught they are safe as houses.......but I have seen some careless use of both.....remember that little inverter the size of two packs of cards will kill you just as easily as the overhead wires in the street.

cheers

[2manylures]

Re: Inverter help

It was just a frickin JOKE

YEAH RIGHT

Sure it was

On a serious note though many would have believed that.

Maybe we saved them from spending a fortune on nothing

[Grand_Marlin]

Re: Inverter help

G'day again,

On boats you very rarely see an earth connection to an inverter.

I have seen one that was connected to the "ships ground" which is a copper plate mounted outside the hull for earthing of the HF radio.

Also, most inverters are mounted where they can't easily be touched.

But, as old boot says - it is the age old problem of potential harm as most dont have or cant have earth protection.

So, the inverter does give quick and easy access to 240v power, but can be, has been, and sadly will continue to be a quick and easy source of death in the wrong environment.

As Frank says - the drier the environment the better.

Cheers

Pete

[Fed]

Re: Inverter help

The instructions you quoted sound a bit vague FNQ, what do they say word for word or is there a website where we can read them?

This chassis earth suspect I can forget about it it or run it with 12v negative

Not sure exactly what you mean by this but it sounds like you could be heading for trouble.

[oldboot]

Re: Inverter help

I would not be connecting the 240 V earth to the battery negative.

If it was appropriate to connect the 240V earth to the battery negative I will be done within the inverter.

Most of the current or recent inverters make a big deal about high voltage isolation between the 240AC side of the inverter and the DC side of the inverter.

And quite rightly so.......many of the early inverters did not have high voltage isolation between the two and under a failure situation the output voltages could appear at the battery terminals...... not good.

I would realy be thinking twice and then agian before putting any 240V powered item on a boat.........certianly not on an open boat........If you look a AS3000 (the main electrical standard)....there are diagrames about where you can put electrical items in places like bathrooms, kitchens and laundries.

In short if there is any posibility of a splash of water... it isn't on.
In some small bathrooms you cant legaly put the light switch inside the room.

So In my view to safely use any 240V item in a boat it would have to be fully within a completely enclosed cabin and in a position where it was not possible under any situation to have spray or water of any sort contact it.

to give an idea........a simplified view of the regs re 240 on houses.....nothing on the floor within 14 feet of an open shower head or the opening side of a shower enclosure..........nothing on the floor within 10 feet of a bath.... nothing anywhere within 2 feet of a screened shower enclosure, bath, sink, tub or water outlet of any discription..... all distances measure horisontaly then the exclusion goes all the way to the floor and up to 2.5 meters from the floor.

So......it has to be a decent sized boat to get a similar level of safety........(there will be regs on this that I do not have)...... but I think it would be reasonable to say no 240V item within 2 feet of a door, hatch, window or porthole or a sink if you have one.......and nothing within 2 feet of any floor or deck....which in a boat should be assumed to be wet.

I know I'm a bit of a wet blanket on this matter but you get where I am comming from.

cheers

[oldboot]

Re: Inverter help

Oh add to that nothing outside of the 45deg shadow of an overhang.

So the hatch openind to the cab.....draw a line at 45deg away from the top edge of opening into the cab in all directions and unless it is in the shadow.... no 240.

cheers

[Steven78]

Re: Inverter help

One thing to consider without the MEN system RCD earth leakage systems would NOT work. When working up at the mines ALL generators MUST be earth and contain ELCBS "earth leakage circuit breakers" I have seen a few near misses where poor procedures where used and where RCD worked and save lives. It is a major safety issue and has been proven to save lives on work sites. It’s the same thing with UPS technically following AS regs they should be hardwired to earth as they can still supply without been grounded. In a boating situation I would have NO idea what to do as fault currents and earthing could cause other issues.

[oldboot]

Re: Inverter help

Steve..... I can see you are right with me.

This earthing of generators and inverters is an advanced engineering concept & I recon you could get a bunch of engineers and inspectors to argue about this for as long as the air con was cold and sandwedges lasted.

I see the mine site issue as pretty clear as the generator would be connected to some sort of "wiring system" which should have a bond to the greater mass of earth.... no question.

I would argue the same thing for festival stages powered by generators....I would argue that the stage structure should be earthed and so should the generator..... but I have never seen it done.

If we have an appliance directly connected to a portable supply device.... and that device has earth leakage protection......... the protection will work...BUT only within and between the appliance and the supply device.

Now caravans & motorhomes........ooooo........the regulations concerning the wiring of these is well set down.... as is the wiring of caravan parks........if a caravan is connected to a fixed site supplying power..... too easy the supply cable supplies the earth..........what if there is an on boad portable supply device........Hmmmm....... is it different if the portable supply device isn't on board.....hmmm

portable supply device on a small boat..........Hmmm.... i recon that could be an all day conference.

cheers

[PADDLES]

Re: Inverter help

you're a dangerous man old boot. we should bond and earth our installations to eliminate step and touch potentials. the fact that some dodgy operators don't do it doesn't mean that it shouldn't be done. if there is a difference between the potential of the "earthing???" system of the machine and the potential of say the ground or structure you are standing on then current will flow and pain will ensue.

agreed though, people buy/install these inverters at home or in the car or boat and forget that they are a little killing machine in a nice shiny box. they don't earth them, they don't install rcd's and generally don't comply with any of the wiring rules. because it's connected to a battery they think it's all safe.

[oldboot]

Re: Inverter help

Paddles mate.... have I said anywhere that we shouldn't earth or earth bond any sort of installed wiring.....( edit correction..I have reviewed my earlier posts and there is one comment that may be taken the wrong way...I have made a correction)

I am saying in very many cases it simply isn't done...... you will note I have specificaly said is should be.....in the case where there is a "wiring system".

But I have said that In my view there is very little to be gained where a ( portable ) portable supply device is directly connected to a single appliance

You are also getting confused with the issue of earth potential rise....which is a direct result of a reticulated mains system.
If the electrical system is floating there will be no step potentials or earth potential rise.
Remember before RCD we used to use isolation transformers.

Further... the general consumer is not qualified nor capable of making appropriate decisions concerning the connection of an earth to a 240V item.

Now if we are now talking about permanently INSTALLING an inverter we have an entirely different group of circumstances............If such an item is to be installed......it can be very stronlgy argued that is should be bonded...... but bonded to what and why........what are you going to bond it to in a fibregalss boat.

Are we going to bond to the DC negative.....if so why...and what does it achieve.
And if it was the appropriate thing to do why isn't it bonded within the inverter

then we get into metal hulls.......boating people generlay can't even grasp the concept of bonding the DC negative to the hull.

Then... it could be seriously argued....that if it is the installation of a 240V electrical device... it is "electrical work" and should be done by licenced persons.

here is the test......is it wiring associated with an AC circuit above 35V AC and is it anything other than screwing it to the wall and pluging it in.....then it is licenced work.

The earth connection at the inverter will require termination of a wire and connection using tools, likewise the connection at the bonding point also.

So bonding an inverter or a generator is electricians work.

Do you get where I am going with this........technicaly and legaly this is a complicated question.

But the over riding issue is the safety one concerning the use of the portable supply device in that situation in the first place.

It is my view that it is unlikly that safe circumstances will be found for use of 240V in a boat under 30 feet and then the source/s of supply should be fixed in such a manner such that the supply is only used in restricted safe locations within the cabin.

As I have said before.....highly qualified people could argue this one for hours.

My main argument is..... should it be there in the first place.......

cheers

[PADDLES]

Re: Inverter help

i'm absolutely getting your point mate. and yes, i'm talking about permanent and temporary installations. it is 240V work as far as i am concerned and should be designed/installed/signed off by someone licensed to do it. you know yourself that anyone can do anything at anytime if they so choose, it's just when it goes pearshaped and someone's kid is the one lying on the deck having a fit that people will wonder why they didn't get it wired up safely in the first place.

a "floating" earth is not really an earth though is it. if it's potential rises because of a fault it's definitely now not an earth, it's a live conductor. now if you go and grab it whilst your feet (or your other hand) is in contact with something at earth (or a different) potential then there's a potential difference and current will flow and henceforth the pain thing.

you know yourself that bonding is not always about providing a "return" path it's sometimes about simply creating equal potential. ie. earthing systems, cathodic protection. as far as bonding to the dc negative goes, i don't know the answer to that one, technically it shouldn't make any difference i wouldn't have thought.

oh yeah, you've addressed the number one issue here perfectly, remove the hazard from the boat. there's no real reason to have 240VAC on a small boat, with the exception of provision for shore power to a battery charger.

[oldboot]

Re: Inverter help

Ah well here is possibly the issue.......if neither the inverter and the appliance are referenced to earth.....it is not floating.......it is isolated.....

And no it realy isnt an earth......and the whole earthing philosophy is out the window.......to have any issues the device has somehow to be come referenced to earth AND an case earth fault to occur........It is a difficult concept when we have been braught up in an earth referenced electrical world.

So if it realy comes down to it.....I would be very cautious about using any thing that wasn't double insulated with a portable supply device.

If it was my @#$E on the line & I was the responsible person on a construction site.....I would not permit non double insulated tools with portable generators.

Likewise on a medium sized boat...I'd be sticking with double insulated devices.
That is If I couldn't get a satisfactory device on DC.

cheers

[PADDLES]

Re: Inverter help

yeah, it can get very messy very quickly when stuff is not bonded to a common reference. you've hit the nail on the head though with getting the right people to do the job, i've got a mate who's just picked up a new 8.2m cat, he decided he wanted to run a microwave on it (to heat up tv dinners whilst out overnight apparently). he whacked in a massive inverter with no protection, rcd's, circuit breakers, anything. all installed by a dude who installs car stereos. i'm waiting for the novelty of the new boat to wear off before i tell him how bad this install is.

[Fed]

Re: Inverter help

I think FNQ should scan & post the directions so we can decipher them for him. (HINT)