10 gauge wire getting way hot

[dmellich]

Ok, here's a problem for you electrical types.

We recently experienced a near meltdown on the 12 gauge ground wire that comes out of the "distribution block" (new this past season) and feeds into the speed controller. The meltdown was actually the plastic that acts as a case for the metal connections in the block.

There were no problems prior to this incident. Any thoughts?

ps When I say meltdown, I mean the wires got hot enough to soften the plastic

[Andy A.]

Originally Posted by dmellich

Ok, here's a problem for you electrical types.

We recently experienced a near meltdown on the 12 gauge ground wire that comes out of the "distribution block" (new this past season) and feeds into the speed controller. The meltdown was actually the plastic that acts as a case for the metal connections in the block.

There were no problems prior to this incident. Any thoughts?

ps When I say meltdown, I mean the wires got hot enough to soften the plastic

Could you provide some more information?

What was the wire connected to? Were their problems with that component?

Generaly, hot electrical components suggests a high resistence connection. My first guess is that over time vibrations loosened the screw that holds the wires in the block, and the poor connection caused excess heat. Since it sounds like the heat was highest right around the screw terminal, it's a likely culprit.

In any case check that distro block carefully- the heat may have really screwed with it, and it may no longer be safe to use.

-Andy A.

[cvhsrobotics]

Wow that is odd but I am not surprised. I think 8 gauge works well. But I am not sure, I didn't do much electronics this year

[Greg McCoy]

Originally Posted by Andy A.

Generaly, hot electrical components suggests a high resistence connection. My first guess is that over time vibrations loosened the screw that holds the wires in the block, and the poor connection caused excess heat. Since it sounds like the heat was highest right around the screw terminal, it's a likely culprit.

I disagree...hot electrical components often sugesst a very LOW resistance connection. A shorted connection where there is very little resistance can cause more current to flow than the wires can handle. Resistors and resistance in general turn electricity into heat, but they reduce current flow at the same time.

I do, however, agree that more information is needed to diagnose the problem. Was everything functioning properly before the "meltdown"? Is the frame grounded?

[Al Skierkiewicz]

OK,
Interesting discussion so far. Both are/can be right. I think what is the right one here is the loose connections of the wire in the block. It was one of my first concerns when I saw the hardware. The block is made for wires up to #4 guage. When you insert a #10 and tighten the screws, the strands spread out and move up the sides of the block. I raised serious concerns with First early on in the season about this. A fix is to strip the #10 about 3/4-1" and fold over the wire once or twice. (equivalent to three wires) When you insert this bundle into the block, very few of the strands will move up the sides.
Now as to what to do now. Replace the damaged wires and parts. Once they have gone through heat stress, high resistance connections will continue to be a problem. We call it dominoe effect, a heated connection is high resistance, which causes heat, which causes a high resistance...etc. Pictures would be great if you can manage it.

[dmellich]

Originally Posted by Andy A.

Could you provide some more information?

What was the wire connected to? Were their problems with that component?

Perhaps I mislabled the thread - it may have been the distribution block that overheated. Here's the setup:

Ten gauge wire from ground stud to distribution block (I hope I'm identifying it correctly). Twelve gauge wire from distribution block to speed controller. The point of the overheating seemed to be were the 12 AWG wire exited the block. Actually the brunt of the heat seemed to be taken by the block itself. The plastic that separates the metal in the block melted to to the metal.

There were no problems with any components prior to this.

Thanks for all your help.

[Al Skierkiewicz]

Dave,
The diagnosis is the same with a few small observations. The wire from the ground stud to the distro should have been #6 and #12 wire is legal only when used on motor/controllers specified for #16 minimum. If this was feeding the drills, chalupas or FP motors, it should have been #10 minimum.

[Steve W]

I agree with Al. the fact that the problem was were the #12 left the block leads me to believe there is a bad connection at the #12 wire connection. Remember never use wire smaller than recommended. know that weigth is a factor but safety and performance is more important.You get better current flow and efficiency from larger guage wire. Our team uses 6 motor drive and we have yet to overheat any wires. Believe me when I say that we draw a lot of power. We can drain a battery in 2min 20 seconds just running our motors hard.

Listen to Al, rewire and retest.