Five CF recessed cans dimming

[craff]

We have a hallway that opens into a warehouse style space. The open warehouse has high bays (MH400,coreandcoil/277V) and the hallway has the five CF42recessed cans (electronic ballast also 277V). HOWEVER, the cans routinely, and on no specific schedule dim down to 30% for a few minutes. Then they return to normal operation. There are no dimmers in-line. Three of the ballasts (non dimmable) have been replaced, lamps replaced. Both the high bays and cans share the same phase conductor and neutral. So why the heck are they dimming??? I'm thinking its a 60hz cycle issue?

 

[jbelectric777]

How are the cans controlled? Standard 277 rated switch's ? or a contactor? It could be as simple as a bad switch or contact if all 5 do it at the same time. Very much doubt its a frequency issue because you would have more problems than 5 cans. Jumper out the contact points on switch or contactor and see if thats the problem, and if the 5 cans are on a seperate circuit check the connection and try swapping onto a new or different breaker.

 

[Electric-Light]

If it's bi-level ballast, then I can see your claim, but how did you determine it's dimming to "30%" if it's non dimming ballast?

 

[craff]

- Cans were controlled by a Ltg control panel with relays, but we've bypassed that.
- Could harmonics between core and coil and electronic ballasts?
- 2 of the cans are battery b/u emergency
- 5 exits signs are one the circuits
- on said circuit, there are as many as 10 total battery backup fixtures
- Company in this building makes wifi network switches. There is likely and insane amount of wifi related signal within the building.

 

[craff]

After some investigation, it turns out it was related to lamp ambient temperature. The cans sit in a hallway drop ceiling. the area above the drop ceiling does not have openings/vents etc... The hallway is air conditioned below the drop ceiling. There is a difference of 10-12 degrees from above/below drop ceiling. after removing one 2x2 tile adjacent to every fixture, the lamp temp greatly increased along with light output. It seems the lamps need a stable temp range in order to operate correctly.

 

[Electric-Light]

Are you sure the system isn't switching over to battery backup for some reason?

Company in this building makes wifi network switches. There is likely and insane amount of wifi related signal within the building.

That would not affect it. The WiFi does not put out that much power. FCC would not permit it.

 

[stevebea]

After some investigation, it turns out it was related to lamp ambient temperature. The cans sit in a hallway drop ceiling. the area above the drop ceiling does not have openings/vents etc... The hallway is air conditioned below the drop ceiling. There is a difference of 10-12 degrees from above/below drop ceiling. after removing one 2x2 tile adjacent to every fixture, the lamp temp greatly increased along with light output. It seems the lamps need a stable temp range in order to operate correctly.

I fail to see how a ten degree difference in ambient temp. could have this much of a noticeable effect ..... keep us posted.