Adding 12v sockets - separate circuit?

[Gromit]

I have a 1989 32-200. There is one 12v socket in the v-berth, added by OP from what I can see. It is wired into the VHF circuit (!). I am planning on adding another socket in the aft cabin with the idea that both can be used for portable Caframo fans. There is one more 12v socket near the electrical panel for an iPod, fan, etc. I'm not sure at the moment what circuit that is on.

Should I wire all three 12v outlets to a new circuit? Add a 30a circuit breaker for them? Any particular cautions or advice?

Charlie

s/v Valkyrie

 

[Loren Beach]

Our '88 panel has an "Auxiliary" circuit breaker that I have alloted to the 12 volt outlet and all of the cabin fans, including the fan in our Heatercraft engine-coolant-driven heater.
It would be nice to have more breakers... but I have used up all the existing ones.
Does your panel have any breaker postions that presently do not have a breaker installed??

LB

 

[toddster]

Yes, they should have their own circuits. First, you need to imagine what sort of loads might be connected to them. Also what is the rated capacity of the outlet. Do you really want to pull cable heavy enough to carry 30 amps to each outlet?
I figured the Q-beam spotlight and potentially a plug-in inverter would be the heaviest possible loads. Forward and aft outlets got their own separate breakers.

Edit: If you have no more breakers available, you'll need to protect the wires with in-line fuses.

 

[eknebel]

toddster is correct that according to ABYC, they should be separate circuit. Or in a semi-perfect world, like Loren's, at least a logical group(ie all 12vdc outlets). Keep the grouping so that critical systems are not combined; think of what will be off if the fuse blows. As an example, many people tap into the cabin light circuits to add outlets, but if the fuse blows because of your spotlight that you just plugged in, you are now in the dark. Remember that sizing of the fuse or breaker is a function of the cable sizes in the circuit, not the amperage draw of the appliance in the circuit. That being said, size your wire on anticipated current load. A fuse or circuit breaker is sized to protect the smallest wire in its circuit. The fuse can be lower that the rating of the wire, but not higher( ABYC says it is ok use 150% higher, so a 18 gauge wire rated at 20 amps would have a 30 amp fuse).
Fuses and circuit breakers are the primary defense against electrical fires. To be effective, they must be properly sized, and they must be placed as close as possible to the electrical source, most often the buss bar on the circuit breaker panel. Good luck, and remember to turn the batteries to off before working on the the electrical panel. While 12v is difficult to get electrocuted with, you can certainly melt wires together and make even more work for yourself!

 

[rwthomas1]

I added a breaker and two 12volt plugs right by the galley mainly to charge stuff, run a spotlight, etc. I also added my LED engine room and lazarette lights to that circuit since it was handy and they draw so little power. RT

 

[Gromit]

Thank you all for the great advice. I do have two open positions on my panel. I think I will use one to group all of the 12v outlets. It was especially useful to learn about sizing the circuit breaker to the wire gauge and not the anticipated load. I'll size everything to the anticipated load. Generally it will be very low amperage stuff like the fans and the iPod but I'll consider the spotlight as I size it.

I really appreciate this forum. Thanks, guys.

 

[eknebel]

Glad to help, I was just in your area this weekend, enjoying a few adult beverages at Thursdays Steak and Crab house. Galesville is a nice daysail from Annapolis.