JBE
New member
- Location
- Canton, GA
Good afternoon, first post here, but I really enjoy and appreciate the community and gathering much help / information. Thanks guys!
So here's what I ran into and would love some feedback as to if I'm on the right track or not:
In a commercial restaurant, we used shared neutrals (and breaker handle ties) on many of the lighting circuits. Some lights are incandescent and some are factory LED fixtures and some are LED lamps in regular fixtures.
The restaurant wants all lights on dimmers. We did a bit of research about the fixtures / lamps involved and all said that they would work on normal incandescent dimmers so that is all we installed and we did not use any LED-CFL dimmer switches.
There were two switch legs in the bar area that were on separate circuits (3 & 7, with 3-5-7 sharing neutral).
Switch #1 controls only incandescent rope lighting in cabinetry.
Switch #2 controls incandescent sconce lights and one factory LED down light in the ceiling.
After a year the dimmer switch on the rope lighting (Switch #1) melted and the restaurant had a "handyman" replace it with a new dimmer. A few days later they noticed that when (switch #2) was dimmed at a certain level (say 65%) it would cause (Switch #1) to strobe completely on/off! Not just flicker. So adjusting one switch caused the other to go into crazy mode, even when they were on separate power sources & switch legs. The only things the two had in common was the shared neutral and the conduit that they ran through to that area.
All the wiring, taps, voltage, etc. was in good shape. I tested the switch legs individually and also the neutral wire being shared between them and all checked out good. When one switch was on, the shared neutral would drop in ampacity as the other turned on. So the cancelation of ampacity was working in the right direction. Not adding on.
I noticed that the dimmer that the handyman had installed on switch # 1 (rope lights) was an LED-CFL-Incandescent dimmer. So I replaced it with a 1000W "Incandescent only" dimmer for the incandescent rope lights and the strobing went away. Problem solved... for now.
All that to get to my questions / pondering:
1) Do you think this was a frequency issue? Switch #2 had one LED light on it, and when it was dimmed down to a certain level it sent switch #1 (Incandescent rope lights on a LED-CFL dimmer) to strobing. Was this a result of the LED light frequency messing with the seperate LED-CFL dimmer that was sharing a neutral / conduit?
2) Switch #1 with the incandescent rope lights had over-heated after a year. Is this a related issue? Could the mixed dimming (Incandescent & LED) on one switch cause some sort of "feedback" that would effect a different light switch / circuit and cause it to melt?
What I told the customer is that I think it was a frequency thing from the one LED light being dimmed effecting the other LED-CFL dimmer frequency. Not that it is on an "incandescent only" dimmer, that took away the frequency issue. That is all the BS that I could come up with.
But I wonder if I was way off base or what other ideas are out there.
Thanks for think'n on it.
So here's what I ran into and would love some feedback as to if I'm on the right track or not:
In a commercial restaurant, we used shared neutrals (and breaker handle ties) on many of the lighting circuits. Some lights are incandescent and some are factory LED fixtures and some are LED lamps in regular fixtures.
The restaurant wants all lights on dimmers. We did a bit of research about the fixtures / lamps involved and all said that they would work on normal incandescent dimmers so that is all we installed and we did not use any LED-CFL dimmer switches.
There were two switch legs in the bar area that were on separate circuits (3 & 7, with 3-5-7 sharing neutral).
Switch #1 controls only incandescent rope lighting in cabinetry.
Switch #2 controls incandescent sconce lights and one factory LED down light in the ceiling.
After a year the dimmer switch on the rope lighting (Switch #1) melted and the restaurant had a "handyman" replace it with a new dimmer. A few days later they noticed that when (switch #2) was dimmed at a certain level (say 65%) it would cause (Switch #1) to strobe completely on/off! Not just flicker. So adjusting one switch caused the other to go into crazy mode, even when they were on separate power sources & switch legs. The only things the two had in common was the shared neutral and the conduit that they ran through to that area.
All the wiring, taps, voltage, etc. was in good shape. I tested the switch legs individually and also the neutral wire being shared between them and all checked out good. When one switch was on, the shared neutral would drop in ampacity as the other turned on. So the cancelation of ampacity was working in the right direction. Not adding on.
I noticed that the dimmer that the handyman had installed on switch # 1 (rope lights) was an LED-CFL-Incandescent dimmer. So I replaced it with a 1000W "Incandescent only" dimmer for the incandescent rope lights and the strobing went away. Problem solved... for now.
All that to get to my questions / pondering:
1) Do you think this was a frequency issue? Switch #2 had one LED light on it, and when it was dimmed down to a certain level it sent switch #1 (Incandescent rope lights on a LED-CFL dimmer) to strobing. Was this a result of the LED light frequency messing with the seperate LED-CFL dimmer that was sharing a neutral / conduit?
2) Switch #1 with the incandescent rope lights had over-heated after a year. Is this a related issue? Could the mixed dimming (Incandescent & LED) on one switch cause some sort of "feedback" that would effect a different light switch / circuit and cause it to melt?
What I told the customer is that I think it was a frequency thing from the one LED light being dimmed effecting the other LED-CFL dimmer frequency. Not that it is on an "incandescent only" dimmer, that took away the frequency issue. That is all the BS that I could come up with.
But I wonder if I was way off base or what other ideas are out there. Thanks for think'n on it.