Originally Posted by frank Last night while adding circuits to a 200a panel i found that someone had fed a second panel by terminating the feeders on the main lugs of the first panel.The feeders to the second panel are smaller and warm to the touch.I didn't have time find the distrobution breaker to check It's size.I asked around and was told that just because the wires are warm dosen't mean it's a problem.I'll have to check it with the IR gun tommorow.thanks You are telling us that you found conductor insulation hot enough to the touch and did not investigate further?That to me alone, would ring alarm bells.You'd better hope that them wires don't get any hotter, this is how building fires start.It is not a IR gun you need, it is a clamp meter. Having said that I would have cut the supply to that place before things got much worse.

- Joshua Kinger (Sekiu, WA), 03/25/2017

Mike has a good point ... the temp you feel at one point may be quite a bit different at another point in the run. The source of the problem could very well be that improper connection at the start of the circuit. IR guns have their uses ... but they are no substitute to proper installation. Shoving two wires into a single lug is a pretty basic error. Otherwise ... to answer your question ... you start running into trouble at 75C ... even if the wires have a higher rating on their particular insulation. Why? Because the places where the wires terminate are often only rated at 75C.

- Lewis Douglas (Harvey, ND), 03/25/2017

Move the sub panel feeders to a breaker that is the right size for the wire and the main in the sub. It's possible the doubling up on the wires under the lugs have come loose. There should not be more than one conductor in each lug unless the lug is rated for two conductors. You have no overcurrent protection on the feeder. And if you don't have a main in the sub you could be in real trouble. That means no protection at all. Hot wires are the result of two things, overcurrent or loose connections. This should be addressed today.

- Myrna Smith (Mound City, KS), 03/25/2017