Photocell question...

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maybe I'm a dummy, or I'm not following along properly with this thread, but 208 volt photocells (at least the ones we use - made by Tork) only break one leg of the 208v supply.

Three wires:
black - one leg of 208
red - switched leg of above, goes to ballast
white - second leg of 208 and "T-tapped" to ballast

208v powers photocell, but only one leg is being switched.
 
EBFD6 said:
maybe I'm a dummy, or I'm not following along properly with this thread, but 208 volt photocells (at least the ones we use - made by Tork) only break one leg of the 208v supply.

Three wires:
black - one leg of 208
red - switched leg of above, goes to ballast
white - second leg of 208 and "T-tapped" to ballast

208v powers photocell, but only one leg is being switched.
Click to expand...

OK, you have a 208 photocell and that will work on 208

The opening poster wants to use a 120 volt cell to switch the 208.

Now another issue, 2005 NEC 410.54 prohibits just breaking one leg to ballasted fixtures.
 
I agree, 120v photocell I do not believe will work.

My point was simply that switching only 1 leg of 208 is done all the time, but the photocell is rated for 208-277 as you pointed out.:smile:
 
EBFD6 said:
My point was simply that switching only 1 leg of 208 is done all the time, but the photocell is rated for 208-277 as you pointed out.:smile:
Click to expand...

It may be done all the time but the NEC prohibits it for ballasted fixtures. :)
 
Beating The Dead Horse

Beating The Dead Horse

It's not legal. Don't do it. Listen to Bob. Switch all ungrounded conductors.
 
CCCI said:
Why did you have to go and say that? Some of us maintenance men are Master Electricians and have electrical cards in many states.
I'm just picking on you.
I do think that you will get someone hurt or killed by this practice and if it was not made and tested to do this, you should not ever do it.
Spend the money and do it right.

Michael Hester
Master Electrician and yes, Maintenance Electrician
Campus Crusade for Christ
Click to expand...
In 480's defense,,,,he did say unlicensed maint. man...Hard to be a master electrician without a license.:)
 
iwire said:
Exactly. :)

By the way, I did not see it mentioned but switching just one leg of 208 puts 208 volt across the switch, not 120.
Click to expand...


I mentioned it in my post here...

Mike said:
If you do use it on 208 you are assuming that the solid state electronics can handle the 208 volts. Granted the photo cell will see 120 but when it closes it will still see 208 across the triac . In any event the current rating will at least be cut @in half.
Click to expand...
 
iwire said:
OK, you have a 208 photocell and that will work on 208

The opening poster wants to use a 120 volt cell to switch the 208.

Now another issue, 2005 NEC 410.54 prohibits just breaking one leg to ballasted fixtures.
Click to expand...

But, the NEC doesn't govern the fixture manufacturers. If the photocell incorporated with the fixture, provided as a fixture part or accessory, integral to the fixture itself isn't really the fixture's "switch." It's a feature. And it's UL listed.

So the only way to turn these fixtures "off" is to throw the breaker, so be it, the breaker becomes the switch, and everything is jake.
 
LawnGuyLandSparky said:
iwire said:
Now another issue, 2005 NEC 410.54 prohibits just breaking one leg to ballasted fixtures.
Click to expand...

But, the NEC doesn't govern the fixture manufacturers. If the photocell incorporated with the fixture, provided as a fixture part or accessory, integral to the fixture itself isn't really the fixture's "switch." It's a feature. And it's UL listed.
Click to expand...

I already said pretty much exactly that in post #39 :D

But I do not believe the OP is talking about a factory installed photo cell.
 
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