Photo cell control

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guesseral

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Why do manufactures make 240 - 277V photo cells and show in the wiring diagram the photo cell only breaking one leg of the two ungrounded conductors supplying the circuit? I see the application for 120 and 277V when there is one unground and one grounded leg but not when there are two ungrounded legs, this is against code articles 410.48 and 410.54 B isn't it?
 
410.48 is referring to lampholders, not photocells. 410.54 IMHO is talking of auxilary equipment as in contactors....could be one of those judgement calls.
 
"Auxiliary equipment" is the ballast and if the ballast is fed from two ungrounded conductors, then 410.54(B) or 410.104(B) in the 2008 code requires that the controller open all of the ungrounded conductors.
 
Thanks for the answers, but there doesn't seem to be any spicific answer or place that states that a control device has to break both legs. Or atlease the manufactures don't seem to think so! I never gave it any thought when doing the work myself because two pole power alway's got a contactor or 2 pole time clock and the photo cell controled that (those). But now when one of my guys say's here's the manufactures directions why do it any other way.......the only reason I can come up with is because I said so, and I don't like to do that I always want to have a code reference if possible. I have sent an email to one of the manufactures to see if I get a response (yea sure) I just feel it is a large safety concern to have an unswitch leg hanging out there for the unsuspecting service guy!
 
guesseral said:
Thanks for the answers, but there doesn't seem to be any spicific answer or place that states that a control device has to break both legs. Or atlease the manufactures don't seem to think so! I never gave it any thought when doing the work myself because two pole power alway's got a contactor or 2 pole time clock and the photo cell controled that (those). But now when one of my guys say's here's the manufactures directions why do it any other way.......the only reason I can come up with is because I said so, and I don't like to do that I always want to have a code reference if possible. I have sent an email to one of the manufactures to see if I get a response (yea sure) I just feel it is a large safety concern to have an unswitch leg hanging out there for the unsuspecting service guy!
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Yeah I got zapped about a year ago from a 240 volt street light. It was my first time servicing or working on one and I was installing a photocell near the bottom just above the electrical cover plate on the pole and it was a black and white wire if I remember correctly and I had tested the black to ground and read 120 so assumed it was a 120 Volt light and got lit off the white (ungrounded conductor).
 
steelersman said:
. . . I had tested the black to ground and read 120 so assumed it was a 120 Volt light and got lit off the white (ungrounded conductor).
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Wow. Maybe someone should suggest that they add something in the NEC that says that white wires used as hots have to re-identified with another color. :cool:


But it really points out that one should rely on a disconnect, and not a controller, to deenergize a circuit.
 
LarryFine said:
Wow. Maybe someone should suggest that they add something in the NEC that says that white wires used as hots have to re-identified with another color. :cool:
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THAT WHITE GROUNDED CONDUCTOR. IT CAN STILL GET YOU !
IF THEIR IS A LOAD ON IT. :smile:
 
guesseral said:
Thanks for the answers, but there doesn't seem to be any spicific answer or place that states that a control device has to break both legs. Or atlease the manufactures don't seem to think so! ...
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410.104(B) clearly requires that the control device open all of the conductors to the ballast.
410.104(B) Switching. Where supplied by the ungrounded conductors of a circuit, the switching device of auxiliary equipment shall simultaneously disconnect all conductors.
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