Single switch for electronics

[juggernaut]

Just wanted the some thoughts and ideas on using a single switch for the following electronics only - have included fuse ratings.

Garmin 750s 3amp
Nmea 2k backbone 3 amp
Garmin gfs 10 fuel flow sensor .25 amp
Furuno 587 2 amp

Total 8.25 amps

The purpose of a single switch is to switch off the power feeds for the above electronics for those times I am on the boat with the 750s and 587 removed for security purposes as they are bail mounted. A secondary purpose is that I don't want to have live feeds on the dash when the 750s and 587 are removed due to the possibility of water ingress causing a short.

I have carling contura switchs which are rated to 20 amps.

Options include:

Run the load from the switch to a bus bar and wire electronics up to the bus bar/terminal block.

As above but using a terminal block with jumpers.

Run a second blue sea blade fuse block as a sub fuse block for the electronics and use thermal breaker with a switch such as a blue sea 285 or 187 series mounted under the dash. Only problem i see with the blade fuse block is that the fuel flow sensor has a fuse of .25 amps and I cant seem to find a blade fuse rated that low. Accordingly I would have to still fuse this with glass fuse.

Other options?

If I go for one of the first two options is the carling switch sufficiently rated or should I use a relay and use the switch to operate the relay only.

The switch would only be operated when the electronics are removed otherwise it will be on for the main part and would be switched off using the house battery switch when the boat is not in use along with everything else.

Thanks in advance.

[Dignity]

Juggernaut, are you making it more complex than necessary, I read the part about water ingress and then realised that the Garmin 750S doesn't have a cap to put on the power/transducer connection any way so water is going to get into it regardless and cause you grief at that end eeventually. Not sure about the Furuno 587 but probably similar problem, also not sure how these would cause a short but then I am not a sparky.

[honda900]

Just wanted the some thoughts and ideas on using a single switch for the following electronics only - have included fuse ratings.

Garmin 750s 3amp
Nmea 2k backbone 3 amp
Garmin gfs 10 fuel flow sensor .25 amp
Furuno 587 2 amp

Total 8.25 amps

The purpose of a single switch is to switch off the power feeds for the above electronics for those times I am on the boat with the 750s and 587 removed for security purposes as they are bail mounted. A secondary purpose is that I don't want to have live feeds on the dash when the 750s and 587 are removed due to the possibility of water ingress causing a short.

I have carling contura switchs which are rated to 20 amps.

Options include:

Run the load from the switch to a bus bar and wire electronics up to the bus bar/terminal block.

As above but using a terminal block with jumpers.

Run a second blue sea blade fuse block as a sub fuse block for the electronics and use thermal breaker with a switch such as a blue sea 285 or 187 series mounted under the dash. Only problem i see with the blade fuse block is that the fuel flow sensor has a fuse of .25 amps and I cant seem to find a blade fuse rated that low. Accordingly I would have to still fuse this with glass fuse.

Other options?

If I go for one of the first two options is the carling switch sufficiently rated or should I use a relay and use the switch to operate the relay only.

The switch would only be operated when the electronics are removed otherwise it will be on for the main part and would be switched off using the house battery switch when the boat is not in use along with everything else.

Thanks in advance.

JuggerNaut,

I have Powered my NMEA back back bone off the main power bus bar, so when the Main power switch is on, the back bone has instant power. devices not turned on, dont draw power.

I have powered my Garmin 750 and Furuno 585 from the same single switch (due to lack of switches), and they work fine, the switch has a single blade fuse, and each device has its own inline fuse between the switch and the device.

Hope that makes sense.

Regards
Honda.

[Lancair]

Juggernaut, what your trying to achieve is how light aeroplanes are setup. One main power switch to power everything EXCEPT the radios and navigation equipment. These are powered by an additional Avionics Master switch with everything downstream from one bus bar fused with resetable circuit breakers.

[tunaticer]

Just be sure to run the fuses that comes with each item after the switch. A simple bus bar after the switch will make things tidy and easy to maintain. I would be looking for a switch with 15 amps rating minimum and fuse that to just under it's capacity.

[myusernam]

Bah,
Most of those systems wont draw anywhere near the fuse rating. the fuse is to sop a fire. not protect the unit. If the unit draws to much current for some reason then it is already FUBAR. throw them all on a switch and put 5 amp fuse in there. It'll be plenty.

[juggernaut]

Juggernaut, are you making it more complex than necessary, I read the part about water ingress and then realised that the Garmin 750S doesn't have a cap to put on the power/transducer connection any way so water is going to get into it regardless and cause you grief at that end eeventually. Not sure about the Furuno 587 but probably similar problem, also not sure how these would cause a short but then I am not a sparky.

Yes, probably making it more complex than necessary - I do tend to over think things unless it involves the missus in which case I underthink things

No expert myself but possible short if water created a conductor between the live plugs and the boat itself (aluminium)?

Perhaps all i need is to protect the plugs ends.

JuggerNaut,

I have Powered my NMEA back back bone off the main power bus bar, so when the Main power switch is on, the back bone has instant power. devices not turned on, dont draw power.

I have powered my Garmin 750 and Furuno 585 from the same single switch (due to lack of switches), and they work fine, the switch has a single blade fuse, and each device has its own inline fuse between the switch and the device.

Hope that makes sense.

Regards
Honda.

Makes perfect sense Honda. Very similar to what I was conceptually thinking except your nmea backbone is powered of the main bus whereas I was thinking of having on the same switched circuit as the sounder and plotter.

Juggernaut, what your trying to achieve is how light aeroplanes are setup. One main power switch to power everything EXCEPT the radios and navigation equipment. These are powered by an additional Avionics Master switch with everything downstream from one bus bar fused with resetable circuit breakers.

I was actually going to run a sub circuit of the main circuit - so not actually a separately powered circuit - rather a separately switch circuit.

BTW commercial fishing boats have to run a dedicated power feed directly off the battery for radio communications. Not sure about nav gear.

Just be sure to run the fuses that comes with each item after the switch. A simple bus bar after the switch will make things tidy and easy to maintain. I would be looking for a switch with 15 amps rating minimum and fuse that to just under it's capacity.

The items come with glass fuses which I was going to cut off and use blade fuses where possible for improved reliability (nmea backbone will have to retain a glass fuse as it is only .25A.)

Bah,
Most of those systems wont draw anywhere near the fuse rating. the fuse is to sop a fire. not protect the unit. If the unit draws to much current for some reason then it is already FUBAR. throw them all on a switch and put 5 amp fuse in there. It'll be plenty.

I realise they won't draw anywhere the fuse rating - I only included the amp ratings in case anyone wanted to comment on circuit protection with regards to the single carling contura switch which is rated at 20 amps. I assume the 20 amp switch i had earmarked for this purpose will be fine then.

Thanks everyone for your input.

[Dignity]

Interesting but I will have another look at the fuse on the Garmin 750S next time I am home as recently when I tidied up the wiring I was sure that the glass fuse looked like a "slow blow" fuse, at least that is what it looked like as I have a reminder in my trusty little note book to check it out and get a spare for it.

[Dignity]

Yes, probably making it more complex than necessary - I do tend to over think things unless it involves the missus in which case I underthink things

It's a bit about the bloke who found a bottle with a one wish Genie, he wanted a bridge built to Hawaii as he hated flying and ships, The genie asked him to reconsider due to the amount of resources required. He then asked to be able to understand women to which the Genie asked "Do you want 2 lanes or 4 lanes for that bridge"

[Noelm]

Not too sure why you actually need another switch for accessories, all the equipment listed have their own on/off switches, when the boat is not in use, then the battery is switched off anyway (usually) what you are doing (in effect) is switching the unit off, and then another switch "just to be sure". Dignity, the 750S does have a rubber cap to fit over the plug when the unit is removed.

[juggernaut]

Noelm I am not wanting a second switch when the boat is not in use.

I am wanting a second switch when the boat is in use when the Furuno and Garmin are removed (they are bail mounted) so that there is no power to the plugs when they are removed.

[aus2045]

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[juggernaut]

Interesting but I will have another look at the fuse on the Garmin 750S next time I am home as recently when I tidied up the wiring I was sure that the glass fuse looked like a "slow blow" fuse, at least that is what it looked like as I have a reminder in my trusty little note book to check it out and get a spare for it.

The instal instructions say an AGC fuse which I understand is a fast acting fuse....so a blade fuse would be OK?

[Dignity]

juggernaut - I will revisit, it is just that I remember the old slow burns used to look like the one that was with the unit, I guess I should read up on the specs a bit more.

Noelm, I now dimly remember there was a cap for the plug, I have had the wiring in and out a few time as I had to repair some holes left in the dash with other instruments and it has been misplaced. I will add that to my notebokk to look for it.