12v electric fixtures, what do you use?

[turf]

howdy again,

started wiring my bus for 12v loads, lights, water pump,....

well, i got the wires in place. now, i'm not sure how to attach them or leave them until im ready. this is kind of in between household wiring and auto wiring.

my questions for the group: for 12v, do you terminate you wire in a standard electric box, and cover that with a plate?

it seems that 12 switches and such are meant for drilling holes through the wall and mounting the switch to a wall instead of a electric box.

to join 2 wires together, auto wiring uses terminal blocks and house wiring uses wirenuts.

so, whats up with the 12v wiring? do you use standard house switches and boxes? or a modified auto style wiring?

any help appreciated!

thanks

[bansil]

You can use standard 120v switches for 12v THEY WILL NOT LAST though,they 12v will erode the contacts very quickly due to having higher amp loads than 120v for same size item(people still do it though)

You can put 12v buolb sockets insie 120 lamps and convert them to 12v if you want all to match

[lornaschinske]

I use an inverter to power 110vAC flourescent lights. It's much cheaper. Like half the cost of 12vDC lights.

I've posted several links to websites that show how to wire 12vDC. Of the top of my head, tryThe 12 Volt Side of Life pt 1 and pt 2. Solar sites have good info on switches to use.

We used wire nuts to wire up 12vDC in the past. Bought cheap automotive flourescents... replaced after a few months because they burned up. If I had to use 12vDC lights, it would be Thin lites and they are pricey. Inverter gives us more bang for the buck.

[Redbear]

The connections have to be more secure with DC. Your current is higher to make the same make wattage on the lower voltage. A pair of 55-watt headlights draw about 9 amps, but a pair of 60-watt AC bulbs draw only 1 amp on AC. A little bit of resistance in a connection makes a little bit of heat on AC, but makes 100 times the heat* for the same power draw at 1/10 the voltage.

Terminal blocks are great. Wire nuts work on DC, too. (I'm a belt-and-suspenders type of guy. I make the mechanical connection by twisting the wires, then solder them, then put on the wire nuts to secure them, then put tape around the skirt of the wire nut to prevent anything from poking up into the metal.)

Some of the switches you can buy have both AC and DC ratings, others are AC only. (That doesn't stop Fleetwood from using AC-only switches on DC, but I digress.) Look at the fine print on the switch, or the box in the bin if buying new ones.

You can mount switches meant to be drilled into a panel into regular wiring boxes by getting blank plates and drilling holes as you see fit. They come in the standard plastic covers plus shiny chromed metal.

The simplest way to have power outlets is to drill blank plates and put cigarette lighter sockets into them. Regular automotive accessories can plug in. You can also buy the blank plates with the sockets pre-installed. I would be cautious with this over 10 amps, and not use it for anything over 20 amps. I have also seen off-grid homes where the DC wires went to oddball polarized receptacles and matching plugs, so the DC devices cannot be plugged into the AC inverter plates, and the AC cords cannot be plugged into the DC.

[tech rant] The electrons all travel in one direction, so they must be able to cross over any junction. With 60 Hertz AC, the electrons go left 60 times, and right 60 times, reversing direction 120 times per second, 7200 times per minute. So if there is a gap, if the electrons on one side can magnetically move the ones on the other side of the gap for a few milliseconds before changing direction, the circuit is complete. That is why a capacitor, with a dialectric insulator, can 'pass' AC but blocks DC after a short charge up time period when all the electrons stack up on one side of the insulator.

* E=IxR. One ohm of wiring resistance passing 2 amps = 2 volts drop, 2 volts x 2 amps = 4 watts dropped as heat. One ohm of wiring resistance passing 20 amps = 20 volts, 20 volts x 20 amps = 400 watts of heat. [/tech rant]

[wmkbailey]

Originally Posted by Redbear

[tech rant] The electrons all travel in one direction, so they must be able to cross over any junction. With 60 Hertz AC, the electrons go left 60 times, and right 60 times, reversing direction 120 times per second, 7200 times per minute. So if there is a gap, if the electrons on one side can magnetically move the ones on the other side of the gap for a few milliseconds before changing direction, the circuit is complete. That is why a capacitor, with a dialectric insulator, can 'pass' AC but blocks DC after a short charge up time period when all the electrons stack up on one side of the insulator.

* E=IxR. One ohm of wiring resistance passing 2 amps = 2 volts drop, 2 volts x 2 amps = 4 watts dropped as heat. One ohm of wiring resistance passing 20 amps = 20 volts, 20 volts x 20 amps = 400 watts of heat. [/tech rant]

You are making me misty eyed for my Navy days.

[jazty]

For 12v receptacles I think I'll go with these: http://www.amazon.com/High-Quality-B...=blue+sea+1011 (Blue Sea 12v Socket 1011). I ordered 2 from Amazon to test out and they seem to be decent quality. The big selling point is that if you use the Blue Sea cigarette plug it will lock into the socket until twisted and pulled out, though it still can be used for normal cigarette plugs. That's always been my biggest gripe with the standard 12v cigarette lighter sockets: the plug starts popping out, loosing contact, heating up and melting the tip. We'll see how these fair.
I'm planning on drilling two holes in this (http://www.leviton.com/OA_HTML/Produ...minisite=10251) to accommodate two sockets and then I'll install them in a normal electrical box next to the AC.