bank of fluctauating light brightness.. bizzare

[leo95se]

baffling issue - We have a bank of lights in a new space just built out. There is one circuit feeding an area of a floor. half of the lights on this circuit randomly dim and brighten, from 350 to 500 lux. the odd part is that there are a handful of emergency lights scattered through this area as well, and they equally dim and brighten.

one would assume there is a grounding issue. all grounds are clean, and separate on the 2 sources. the tie in where this bank connects to the remainder of the circuit is secure as well.

my next guess is some sort of frequency issue, but cant trace to anything in the area (security wiring, fire alarm wiring, AV wiring).

ANY ideas?

Thanks a ton for the help.

 

[Skogsgurra]

Frequency inverters are known to do unexpected things to the grid. Are there any variable speed fans, pumps, escalators, lifts or other VFD installations?

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[roydm]

Sounds to me like you are loosing your neutral connection and the lamps are operating in series parallel phase to phase rather than phase to neutral.
Roy

 

[dpc]

What type of lighting?

"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg

 

[leo95se]

we have an elevator nearby, but these are the only affected lights. the closer ones arent.
VFDs yes, but again, not nearby or off the same panel.

lighting consists of two types: 277V electronic ballast, direct/indirect fixture; and recessed pendant type, i dont know this info offhand but will look.

re: loss of neutral, this would typically occur, but how could both emergency/gen powered and normal powered both be affected?

is it possible that the two styles of fixtures are creating problems? perhaps ballast incompatibility creates harmonics?

thank you everyone..

 

[waross]

Is your voltage stable at the lights?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[leo95se]

yes, as metered at the panel. maybe i should meter a line in the ceiling though.

 

[itsmoked]

Loose connection?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

You should meter at a problem lamp. Measure across the feed to the lamp or ballast, not hot to ground. Please be careful, there is a good chance you may have an open neutral and open neutrals sometimes present shock hazards in unexpected places.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BJC]

Draw a circuit diagram. It's pretty simple- breaker,wire, load, neutral.
On paper it's pretty simple. Your office is not wired that way. It's got to be traced wire by wire, load by load (fixture) and corrected.
Who wired it? I would have the contractor who did it back and let hime go home when it's working.

 

[leo95se]

update - appeared to be a bad ballast. one in the whole string was affecting all nearby lights. it doesnt explain how it could affect those on an emergency ckt, but it could have just been an illusion.

 

[itsmoked]

Thanks for coming back. we all learn that way.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Could it have been drawing so much current that it was causing a voltage drop on that circuit?


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[waross]

I agree with jraef's suggestion.

Bill
--------------------
"Why not the best?"
Jimmy Carter