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#58356 11/07/05 05:58 PM
Joined: Mar 2001
Posts: 2,056
R
Redsy Offline OP
Member
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.

#58357 11/07/05 06:03 PM
Joined: Dec 2004
Posts: 1,064
D
Member
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.........

#58358 11/07/05 06:06 PM
Joined: Jun 2005
Posts: 821
S
Member
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.

#58359 11/07/05 06:09 PM
Joined: Jan 2003
Posts: 4,391
I
Moderator
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. [Linked Image] [Linked Image]

Bob

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


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#58360 11/07/05 06:40 PM
Joined: Mar 2001
Posts: 2,056
R
Redsy Offline OP
Member
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? [Linked Image]




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

#58361 11/07/05 09:44 PM
Joined: Jun 2004
Posts: 206
C
Member
EGC = Equipment Grounding Conductor.

Al

#58362 11/07/05 10:14 PM
Joined: Jan 2005
Posts: 5,445
Likes: 2
Cat Servant
Member
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.

#58363 11/07/05 11:11 PM
Joined: Mar 2001
Posts: 2,056
R
Redsy Offline OP
Member
Thanks again guys.



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

#58364 11/07/05 11:56 PM
Joined: Feb 2005
Posts: 693
L
Member
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 Fine
Fine Electric Co.
fineelectricco.com
#58365 11/08/05 08:09 AM
Joined: Mar 2001
Posts: 2,056
R
Redsy Offline OP
Member
Larry,

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

Thanks.

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