ECN Forum Forums General Topics of the Trade General Discussion Area Panel Board Overheating

I may have missed this information but I do not see where the poster has mentioned the conductor material. Are we discussing copper or aluminum and what size is feeding the panel??

Has he tried shooting the terminals and breaker body with an IFR sensor???


If this has been discussed let me have it

Charlie

Larry, I was asked to look at your post and offer some advice. There is some info missing like breaker size, wire size & type, actual current readings etc that could be helpful. But lets start by what I think the problem is not, harmonics. I cannot possible see how harmonics can be a problem on single phase supplying stadium lights. I believe your factory rep is passing the buck.

If the breakers are hot to the touch, then there has to be significant voltage drop and load current in or near the breakers. Since you did not list the size of the breaker, the current, wire size or type. I cannot pin anything down.

Assuming everything is sized properly I would get my hands on some sort of thermal device and determine what is actually heating up. Is it the breaker or the connection to the breaker. A probe would pin it down

Next get you a true reading rms amp probe and make sure your circuits are not overloaded or near max capacity. It could be you are max capacity and everything is normal.

Sorry I cannot be more specific other than to say if something is hot you have voltage drop and current, no other way around it. Doesn't matter if it is normal load current or from harmonics.

Good Luck
Dereck C, PE

Mhulbert and JBD seem to have mentioned what I also think this may be.
The breaker is permitted to carry a continuous lighting load of 80%. It may well be operating at it's uppermost limit as related to temperature.

The breaker is rated for 167 degrees F.
167 X .8 = 134 degrees.
I do not know if there is a direct correlation of percentage of temperature to percentage of load, so this may be a real stretch.... but if it is that may be close to the temps you are feeling - try to get a temperature reading when you feel them hot, as I would be very interested to see what it is.

Pierre

iwire:

True, this is not a thread about switching power supplies, unless you count some of the new electronic ballast designs intended to eliminate flicker in fluorescent lighting. But I do not know how those units are designed nor have I evaluated them, so I simply do not know. I doubt Larry Ural's issue involves that (but I can't rule it out, either). But I have encountered harmonic issues in single phase power where loads were exclusively switching power supplies. Those issues had nothing to do with overloading the neutral.

resqcapt19:

Other than having actually experienced the problem in one of the places I have worked, there doesn't seem to be a whole lot of documentation on this. But here is one web page that shows some waveforms of loads being considered in the design of AFCI protection devices. Scroll down to number 8 to see a switching power supply. If you're going to put 100 of these in a room, are you going to use the RMS figure, or the peak figure, to calculate load?

http://www.zlan.com/waveforms.htm

Whether or not harmonics is an issue in Larry Ural's case or not, I cannot say (especially since I'm not an electrician ... I just spec work and hire electricians when I need things done). I'd certainly would have suspected loose connections if he had not said everything was tight.

Larry, I do Infrared testing as part of my job. I agree with iwire & Dereck that you do not have a harmonics problem. Please post more of the info others have asked for. Also do a millivolt drop reading across each breaker that is getting hot and post those results. Another question for you, do you know the length of the circuits?
Al