help with 12V circuit

[Greg1410]

Rewiring my 12V circuits. I measured out one circuit, made my cuts, and soldered some splices in. I took the wire back out of the trailer to test it out before the final install. I have my hot wire and ground wire all to connected with some test lights hooked in. Altogether this is about a 60 foot run (hot + ground) and the lights pull no more than 4 amps; I am using 10AWG wire to be safe. Ran a continuity test with a multimeter and all is good. To test, I just touched the ground and hot wire to the battery terminals. The 4 lights I had hooked up barely glowed and the wire turned very hot and melted some of the insulation. I disconnected right away.

The amp pull is minimal, this is a long run, but with 10AWG this should be fine. Any ideas on what the problem is?
Glad I tested this out before putting in the trailer!
Greg

[damonbeals]

Shorted Bulb? It has happened to me, new out of the package and it was shorted. Also a reason why you should add a fuse. And yes 10G should be fine for only 4 bulbs.

Damon
#4827

[Greg1410]

The bulbs are fine. I hook the light fixtures only up to power (not in the circuit) and they work fine.

Could it be a bad solder job? Could it be the fact that the wires on the light fixture (only about 6 inches long) are only 14 AWG?

Greg

[HiJoeSilver]

10 gauge and 24 gauge are plenty.

Did you wire your positive and negative completely separately. They shouldn't touch electrically except through a load.

It sounds like there's a short I there somewhere. You didn't connect the very ends of the wire together thinking they had to make a loop.

Are all your positive junctions well insulated. How did you make the connections where you tap off of the main wire run? Are they well insulated? Could one of those junctions have metal touching ground?

At this point a bad solder job shouldn't cause a problem it would likely just block current flow.

Consider getting a good ratcheting crimper and not soldering. Easier and better way to make the branch connections. You can get a fairly good one for little more than $20. It produces crimps MUCH better than the crimper in the multi function pliers.

[Greg1410]

HiJoe -
Thank you - I think you solved the problem. there are about 5 lights on this circuit, i put in two light fixtures to test and just wired the ground and hot wires together where the other lights were to go to make the loop. Plus I did this on my driveway, so I bet some of the joints were touching the concrete. I will put all lights in and retry.

[TG Twinkie]

Concrete is not conductive. I would use a battery charger rather than a battery. Reasons are obvious. You would not have damaged the wire.

[Greg1410]

HiJoe:

When you ask if my positive junctions are well insulated - In a few places I have a branch coming off the main line that I soldered in. Hard to fit shrink tubing on this type of junction. Is electrical tape adequate? Other recommendations?

By the way, I hear you on the solder, I did crimp some of my other circuits and plan on doing more of this.
Greg

[HiJoeSilver]

Originally Posted by Greg1410

HiJoe:

When you ask if my positive junctions are well insulated - In a few places I have a branch coming off the main line that I soldered in. Hard to fit shrink tubing on this type of junction. Is electrical tape adequate? Other recommendations?

By the way, I hear you on the solder, I did crimp some of my other circuits and plan on doing more of this.
Greg

Electrical tape is just ok. Wrap it really well. This I would recommend only if you can get all the wires to lay in line and then branching from the end of the tape. Wrap the tape several inches either side of the junction. I highly recommend Scotch 88 electrical tape, available most good hardware stores. I'd recommend one layer of friction tape on the outside of the electrical tape, it's usually found near the electrical tape.

[HiJoeSilver]

"just wired the ground and hot wires together"

Yep that'll do it. Perfect short circuit.

I hate to have to recommend this, but since you're at a point when it's easy to do and since you mentioned some insulation melting you should really replace the wires. There's no good way to be sure of the integrity of the wiring insulation at this point. It could be damaged on the inside and not visible on the outside.

Since you can do this wire assembly outside the trailer, put on the game and relax making some new connections.

For future tests consider getting an inline fuse holder available at auto part stores and twist it on to the end before connecting to the battery to provide temporary protection before putting into the trailer.

I know it sucks but good lesson learned the easy way.

[Greg1410]

thanks for your help. I will get that inline fuse.