12V wiring - individual runs?

[EZ]

I am nearing the point where I need to get some wiring installed. With the exception of the porch light all of the wiring will run through the top (front, back) of the enclosure. I was going to run a 'bus' wire from the front to the back over the top and just tap in for the vent fan, dome light, reading lites, fan, etc. It looks like you guys mostly do individual wire runs. I can see where this would be easier to fuse but a lot more wire. I guess fuse-wise that is the best way to go. Any comments please?


Ed

[madjack]

Ed, our original intent was do as you suggested but we bought a roll of 14 ga trailer harness wire and used that...in the end, it was easier/quicked/safer to run seperate wires for each leg including ground wires by splitting the trailer wire in half...we have cabin lights and 12v receptacle together, fan circuit, galley lights and receptacle and water pump circuits
madjack

[SteveH]

Ed,

Another thing to worry about with all those splices in a buss type system is opens at the splice. Personally, I would shy away from it. What I did about wiring was use #12 speaker wire, or it's actually heavy duty zip cord. Went to an electronics wholesaler and bought 100' of it and used it to wire all the circuits. It's cheap, stranded fine so road vibration won't effect it, insulated to 250 volts, and heavy enough to handle the 12 VDC circuits.

[Mitheral]

Cheaper than trailer harness wire is to buy exterior 25-100ft extension cord ((s) as needed) from the local borg (watch for it to come on sale). You get 3 colour coded stranded wires all packaged together in an abrasion resistant casing for (much) less than wire packaged for automotive use.

Check the label, cords are available in 18,16, 14 and 12 guage. Use what is appropriate. If you use several shorter cords you can colour code curcuits using different casings (green for the fan, yellow for porch lights, red for outlets, etc. etc.)

[Loader]

I did individual wires for each item. It was easier to wire, and if something goes wrong in a circuit, I can narrow down the problem faster, and no way will a short to ground on one line cause problems on another (just an example). In this thread, I had posted a couple photos of the basic install adn fuse block.

http://tnttt.com/viewtopic.php?t=7399

[TD4FREEW/CTD]

another reason for not running a single bus wire is simply because your voltage is so miniscule. when multiple items are being used things tapped at the beginning end of your bus wire will recieve full 12v while items at the farther end will be getting skimped on the voltage. it may only be 1-3 volts of loss but when you are dealing with only 12 whopping volts to start, it gets low quick! the electromotive force just is not there. i will however, add that my experience is with 12v AC, im pretty sure the same principles of current draw and voltage drop apply.

heres another reason:

current adds up very fast when dealing with low voltages. theres just no going around it. power = watts and watts are what you need! watts are of course, a combination of voltage and current. current (in amps) x voltage = watts. since power is power and watts are watts no matter how you add em up, it becomes obvious that you will need more current to attain the needed watts when only applying 12v of electromotive force.

now, i dont know how much power people are pulling out of these things, but reasonable saftey common sense would dictate that your bus wire must be able to handle the current that could possibly be pulled through it at any given time. again, i have no idea how much power you guys have the capability to run in a TD. 360 watts would be the maximum you could pull from a 10AWG bus. any larger and you start getting bigger, and pricier wires. myself personally would keep an %80 safety margin, so wattage would really be even lower than the figure i gave.

anyway, i've got one more vote for running individual home runs for most of your items.

i think i've got more to blab about but i cant think of it right now and humans in my dwelling are harrassing me!

good luck,

Karsten.