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#127783 - 12/19/01 07:45 PM 120v photocell
aphares Offline

Registered: 12/17/01
Posts: 39
Loc: Indiana
I encountered something new today about phototcells, but I'm still unsure of how or why I had the problem.
A 120v photocell was cycling on/off in intervals of about five minutes. Now there was a lighting contactor 120v on the load side that pulled approximately .75amps. Also on the load side was two ice cube relays that were 120v coils, that pulled at best .5amps. they were a (honeywell)"for hvac" style relay. that was used to contact other hps lighting. and one neon light.
My first guese was a bad photocell, but I have never seen one cycle before, so further testing was done. by process of elimination.
When the two "honeywell" relays were unhooked from the load side, and only the lighting contactor was hook-up than the cycling would not happen any longer.
Was it all pulling too many amps ? NO. I determand this early on. Even at that is it not that the photocell is rated for it's draw, 15/20amp depending on the rating.
Both "honeywell" relays worked properly.
Was the resistants to high across the three coils ? causing the photocell to see more of a load than what was real. in this case if it exceeded the breaker rating, than why was it not tripping ? (porperly rated). With a digital amp meter the amperage was never a question.
History: the photocell cycled once before, a electrician replaced it about a month ago. I believe he tested the lights in the day, seen they where on, then left. A month later it was noticible they were cycling again. So a new electrician was called. So the photocell was 1 month old. The other relays got hook-up during a remodel, about a year ago. So it's a good possibility that this worked for up to a year in this manner.
I have only seen a photocell good or bad.
It was all wired to code, the "honeywell relays was removed, and the other lighting was routed to the lighting panel, controlled by the lighting contactor. All works fine now, but I'm still dont know why it was cycling ????????

#127784 - 12/19/01 08:14 PM Re: 120v photocell
aphares Offline

Registered: 12/17/01
Posts: 39
Loc: Indiana
P.S. All testing was done with tape over the eye. So false lighting was not the cause.

#127785 - 12/22/01 07:15 PM Re: 120v photocell
nesparky Offline

Registered: 06/21/01
Posts: 650
Loc: omaha,ne
Most of the time I have had a service call about this problem, I found the line and load wires on the photocell to be wired up backwards. ALmost all the rest the photocell was replaced to fix the problem.


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