http://tnttt.com/postin ... ly&t=11230
jmtk not a hijack, we're still talking grounds. I am considering a minor battery for just the lights, that is in normal life an emergency lighting battery. About the size of a motorcycle battery, but 12vdc and considered dry cell, I think. I'd rather have a 4 amp hour lithium, at 12v dc. Then on a separate circuit do the heavy amped system. I have a "jumper system from peak that is a piece of crap for actually jumping a battery with it, but for 12vdc deep charge at higher currents it might do ok. I have a 10 amp, self resetting breaker in the old glass-metal-capped-ends socket style, but open top holder, I wanted to use. I think it was from some power windows. That will breaker the 12vdc outlets (what's a real lighter draw? LOL)
I'm using romex 3wire (I surmise 14 ga) for my 110vac and 16ga. for 12vdc lighting, 14 ga for 12vdc outlets (says it is good for up to lighter's circuits...)
What I haven't' figured out yet was the fuse type for the lights. I have the socketed kind of holders for 110v items like stereos and stuff, that use the glass with metal end cap type fuses. I'll have to stock spares for one thing. lol I've considered bayonette type crimp females to use in conjunction with the larger but new style car fuses.
One thing I will say here. The core of the wire is always based on the strength for your current flow. 20 amps needs 12 ga, whether 12vdc or 110vac. The insulation is different though depending on your voltage and usage area. You need a higher voltage insulation if you are running 110vac, instead of 12vdc. You need gas resistant insulation if it is going to be under a car's hood, plus temperature resistance like if it hits the exhaust.
one other thing while we are talking grounds. I KNOW I should never trust the ball/hitch ground to carry a stead voltage, moving or still. Same with wire connecting to the frame as a ground wire, instead of running a ground (return/-12vdc,black) wire. Especially if the connection is outside where it will get kicked, rained on, possibly salted from the road and corrosion. But one thing I learned recently, it might be better to use a stainless steel bolt with separating washer to separate copper wires from steel frame, and it is DEFINITELY a must do if you have an aluminum frame and copper wires. (go through stainless steel bolt and washers to separate copper from aluminum.)