Hey guyz got a lighting problem for ya'll I have a lighting panel in which 11 of the 12 circuits leave the panel out of one pipe, and it's hot, all the brkrs are 20 amp, the wiring is #12, none are overloaded, I vaguely remember that nonlinear loads can mess up some types of loads, this panel has 9 ckts with hid metal halide, and 3 ckts with flurescents, (277v panel) could this be a harmonics problem????
#2674 - 07/20/0102:23 AMRe: Hot pipes for lighting circuits
You have 22 conductors in what size and type of pipe?
What is the ambient temperature?
Is the pipe pretty uniformly hot or is there a hot spot?
> none are overloaded, Assuming that the circuit breakers are in working order, that probably has to be true based on the #12 takes 20 A generality.
But you have a problem. You've got over 9 conductors in one conduit and you did not derate. So just maybe they are way overloaded.
>I vaguely remember that nonlinear loads can mess up some types of loads, On the branch side, that is a problem only when the neutrals are shared on a multiwire. In that case, the neutrals can be overloaded which means that you need to derate them even further.
Do you have 22 conductors for the eleven circuits or perhaps only 17?
To me it sounds like you need more conduits, heavier wire, and perhaps a neutral per circuit or oversized neutrals.
[This message has been edited by Dspark (edited 07-20-2001).]
#2675 - 07/20/0106:34 AMRe: Hot pipes for lighting circuits
Can you give us more information? What type of wire is it, what are the loads on the circuits?
Assuming it is THHN and that you have a neutral per circuit your capacity would be down to 13.5 amps (45% of 30A) if you are anywhere near that load that explains where the heat is coming from. If you can change these wires to #10s or remove half of them you should be Ok.
#2678 - 07/20/0104:46 PMRe: Hot pipes for lighting circuits
Or perhaps 15 conductors? I guess since this is apparently three phase! Would someone really run three circuits on one neutral with that type of lighting?
Perhaps his neutrals are about ready to melt their 90° thermoplastic off.
Putting half the wires in another conduit won't completely solve the heat problem if the neutrals need upsizing also.
#2679 - 07/21/0112:38 AMRe: Hot pipes for lighting circuits
First I would use my Amprobe just to see if we have a bad connection which I'm sure you did. Next I would worry about the metal halides. Watts? I used to warm up next to those things in the winter!
Bill A. another good answer in my opinion, I bet if he takes out just two halides on each circuit he will see a dramatic loss in temps on the high temp zone. But I still think it sounds like an bad conection prob. Hope he lets us know!
[This message has been edited by Resistor (edited 07-21-2001).]