Buzzing lights

[shelton]

I was talking to a fellow ec and is having a problem with 400 watt mh low bay lights in a local bussiness where they take tours for wine that is made on property the lights are so loud that it is hard to hear over the noise. He has a 400 amp 3 phase 208 service and there is 10 fixtures total some of the fixtures are wired 120 volt and some are wired 208 volt. He also did a building about 2 miles away with the same lights but at that building it was single phase and lights did not make any noise. He has check all connections and cant find what would make them buzz any sugestions.

 

[edamico11]

He also did a building about 2 miles away with the same lights but at that building it was single phase.

Do you mean at that building no buzz? He should take the 208 fixtures off line and see if the buzz goes away.. It will be a good starting point

ed

 

[brian john]

Is this is a refrigatered room?
As noted isolate the 208 lights.
Not sure how many circuits are involved but isolate circuit by circuit to note if problem is system wide or limited to one circuit.
Measure and record voltage at the 120 and 208 lights, with lights on and with the lights off.
Contact the manufacture for any possible ballast issues, temperature limitations and minimum maximum voltage operating limits.

 

[ghostbuster]

Harmonics, possibly from a VFD running the air handlers or refrigeration system have been adversely interacting with ballast systems at other plants we have been involved with.Try turning off all loads except the lights to isolate this problem.