Dimming Lights

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BScottSATX

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I am having a problem with dimming/flickering lights on a recently finshed project. I have 17 Graphic eyes controlling different light in different rooms, as well as local dimmers in some rooms. The problem seems to be isolated to 1 panel, specifically the A phase of this panel. I have checked the resistance of the main breaker at the service entrance as well as the resistance of the circiut breakers feeding the circuits on the A phase side of the panel, all were with in tolerances. I found neutrals of seperate circuits were combined in the Graphic Eye interphases, so they were separated accordingly. Ther is no pattern to the flickering/dimming. The HVAC contractor has soft start kits on all of the A/C compressor motors and have been shut off and restarted while monitoring the lights. No flicker or dimming noticed. The cutomers are out of town for the summer so minimal lights, appliances, computers, etc aer being used. Any further suggestions would be helpful.
 
Buck Parrish

Buck Parrish

Senior Member
Location
NC & IN
Just to be clear is the flickering just on the grafic lighting ? Is all of A panel lighting controlled by grafic eye?
Or are other lights dimming , too?
 
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BScottSATX

Member
Dimming/flickering is occuring on both graphic eye lighting as well as lighting controlled by dimmers. Not all graphic eye units are fed from the same panel. The dimming/flickering is most noticable on circuits fed from the A phase of this particular breake panel, the B phase seems to be unaffected.
 
mcclary's electrical

mcclary's electrical

Senior Member
Location
VA
BScottSATX said:
Dimming/flickering is occuring on both graphic eye lighting as well as lighting controlled by dimmers. Not all graphic eye units are fed from the same panel. The dimming/flickering is most noticable on circuits fed from the A phase of this particular breake panel, the B phase seems to be unaffected.
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What test did you perform on main breaker?
 
Z

ZGjethro

Member
Electric-Light said:
Does phase A flicker when the dimmers on remaining phases are completely switched off?

Are you using a separate neutral for each phase?
If not try, that.

Something else suggested as a solution is to use a line reactor on each dimmer.

Here's a note on this:
http://www.lutron.com/ResourceLibrary/360283.pdf
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second this. I had an install in a three phase system where there was a flashing of the MR16 lamps. The electronic dimmers were sensitive to the harmonics on the shared neutral I had installed. Fortunately it was an easy fix since I had run a conduit to the panel from the multigang switch box.
 
J

jscott

Member
Location
Maryland
dimming lights

dimming lights

it definitely sounds like a neutral problem. had this happen once before where there was a normal dimmer installed on magnetic lo. vo. lights. the lights would almost "pulse" when they were on. it would seem to do it once every one or two minutes. changed the dimmer and all was fine. also, did you check the neutrals in the panel to make sure copper is under neutral screw,not pushed a little too far and under insulation. that would not make proper contact as you would only have bitten into the copper slightly.
 
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BScottSATX

Member
After several trips to the project The dimming has been resolved. There are 2 dehumidifiers wired from the breaker panel in which lighting loads were dimming. The name plates of the units stated 120v 8amp load. Both units were wired on 1 20 amp circuit. When both units started together, amperage was recorded at 54.6 at highest reading causing a large load imbalance between A and B phase.Voltage would drop substantially on A phase as a result. Amperage was monitored for 3 hours and units would run every 15 minutes. Each time one or both units would start the lights would dim. The dehumidifiers are now on their own circuits, and are wired from the service entrance panel. Thanks for everyones help and suggestions.
 
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