Audio pop problem when turning lights on or off.

[Morte615]

A bit of background, we have a commercial service enterance panel that has five 200amp breakers. Each of these breakers go to 5 sub-panels. Now the issue is when we turn the lights on or off from the panel in the front we get a pop (just like turning the board off before the amp) in the audio equipment on the panel in the back. The interesting part is that the audio equipment is on an entirely seperate sub panel!

Trying to trace down the problem so we have some where to tell the electritian to start looking. The main service panel is less than 10 years old but the sub-panels range from 15 through 40 years old.

Could it be an issue with sharing a ground or a neutral wire between the 2 panels (it only happens between these two panels) or any other ideas or solutions?

(Edited to remove asterisks from post)

 

[chausman]

Off topic, but, do the asterisks mean anything significant?

 

[Morte615]

No, i dont know why my cell phone added those. They dont mean anything.

 

[FMEng]

How big are the loads being switched off at once?

Having an electrician look into this is a good idea. I suggest measuring the phase to neutral voltages of the main panel as the loads are switched. A loose lug, anywhere between the service transformer and the main service would cause excessive voltage drop that would vary with load current. The pop may be occuring when the AC supply voltage to some sound system component jumps abruptly when the load is shed.

A good way to identify the culprit is to load up the panel for some time and then check all connections with an infrared thermometer. It's good to check big breakers for excessive heating, as they can fail internally too. Or, just shut the whole thing down and torque all of the bigger connections. If this has been going on for awhile, the electrician may discover arcing, burning and melting connections or odors which makes troubleshooting easy.

If nothing is found there, then I would start isolating the pop to the particular piece of sound equipment producing it. Something may have failing DC filtering or regulation.

 

[Morte615]

The loads are pretty light, 4 or 5 flourcent fixtures in the pro-shop or party area (this is a skating rink) that when turned on or off cause the pop. Recommended a power conditioner but would like to try to find the problem first

Will tighten down all the lugs and see if that helps but I think we will start with trying to find out which piece of equipment is causing the pop in the first place.

 

[headcrab]

I think it would be better to check the temperature of lugs rather than indiscriminately tightening them. It is not impossible that you could over-tighten one and cause more problems for yourself.

If you don't have access to a "thermal imager" (can't think of the name at the moment) you could conceivably do a "fall of potential" test across a termination.

 

[FMEng]

I think it would be better to check the temperature of lugs rather than indiscriminately tightening them. It is not impossible that you could over-tighten one and cause more problems for yourself.

If you don't have access to a "thermal imager" (can't think of the name at the moment) you could conceivably do a "fall of potential" test across a termination.

A qualified electrician will not over torque the connections. That isn't a job for anyone but a licensed electrician.

As for power conditioners, I don't see this situation being solved by one. (Conditoners are not for fixing problems, they are for preventing them.) The noise is indicative of either a problem developing in the sound system, or a power problem. In either case, the real cause should be identified and repaired.

 

[Bsancken]

If you don't have access to a "thermal imager" (can't think of the name at the moment) you could conceivably do a "fall of potential" test across a termination.

Like a FLIR Thermal camera?..