ECN Forum Forums General Topics of the Trade General Discussion Area Backfed Photocell?

A photocell will operate a lighting contactor. If I install a switch to bypass the photocell and energize the contactors coil, the bypass switchleg will also (back)feed into (red) photocell output leg.
Is this a concern?

Thanks.

Not for me....

It is the same phase, right?

Your not really backfeeding it, your applying the same phase on the red wire, as if the photo cell was operating properly.


Dnk.........

Not if its on the same phase. I've wired motion detector lights like this in the past. When the light switch is on, obviously the lights are on. When the switch is off, the motion feature controls the light. I think what you are describing is the same thing.

I do not see any code issue with it.

However another option would be the use of a 3 way switch (SPDT)

Common to contactor coil.

One terminal from constant feed.

One terminal from red of the photo cell.

You end up with ON or AUTO with this set up and no back feed to the red of the cell.

Make sure the EGC is large enough.

Bob

[This message has been edited by iwire (edited 11-07-2005).]

Thanks guys.

The phasing is OK.
I think I actually did this configuration once before, but I'm not sure.
My concern is damaging the photocell.

iwire,

EGC, what's a EGC?




[This message has been edited by Redsy (edited 11-07-2005).]

EGC = Equipment Grounding Conductor.

Al

Not a problem. I usually do this very thing.

You are not "back feeding" the photocell. The photocell is nothing more than a switch. It does not draw any current.

Thanks again guys.



[This message has been edited by Redsy (edited 11-07-2005).]

Redsy, from what I understand, as long as the line (black) wire is hot, there's no harm in energizing the load (red) wire.

Larry,

The line won't ALWAYS be hot when the red is fed from the bypass. Only when the timers contacts are closed.

Thanks.