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#85604 - 07/21/03 04:33 PM Photocell code reference
arseegee Offline
Member

Registered: 01/28/02
Posts: 321
Loc: Statesboro, GA USA
This was asked to me today by another electrical contractor. If a person uses a 120v photocell to break one leg of 240v sign circuit would this be a code violation as long as the ocpd is a double pole? Of course we agreed that a 240v photcell should be used in this situation to de-energize the sign for safety. Any thoughts or code references?

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#85605 - 07/21/03 06:04 PM Re: Photocell code reference
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6805
Loc: Brick, NJ USA
THe bible is in the truck, so I'll give an opinion.
THe photocell is more than likely not being used according to mfg instructions, if it's rated 120 volts.

Breaking one leg is not a good practice, and leaves an energized conductor somewhere btwn the PC and the sign. A sign tech may think the sign is de-energized. This is similar to using a single pole t'stst (line volt) to control a 240 volt bb heater; or a s/p switch to "shut-off" a 240 volt circuit.

"It works, don't it????"
(Famous last words.
John
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John

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#85606 - 07/21/03 06:47 PM Re: Photocell code reference
txsparky Offline
Member

Registered: 05/25/01
Posts: 578
Loc: Magnolia,.Texas U.S.A.
A 240 volt photocell only breaks 1 phase of the circuit anyway? At least, that is all that I have ever seen.

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Donnie

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#85607 - 07/21/03 06:52 PM Re: Photocell code reference
caselec Offline
Member

Registered: 04/14/02
Posts: 557
Loc: San Jose, CA
The only difference between a 120 volt photo control and a 240 volt photo control is the heater voltage. If you use a 120 volt control you will need a neutral for the control but if you use a 240 volt control the white wire from the control is connected to the other leg of your circuit and a neutral is not needed. Standard photo controls will only switch one leg of your circuit. I have never seen a 2-pole control.

Curt
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Curt Swartz

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#85608 - 07/21/03 06:54 PM Re: Photocell code reference
caselec Offline
Member

Registered: 04/14/02
Posts: 557
Loc: San Jose, CA
I was just going to look for a diagram to post but it looks I was too slow.
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Curt Swartz

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#85609 - 07/21/03 07:57 PM Re: Photocell code reference
arseegee Offline
Member

Registered: 01/28/02
Posts: 321
Loc: Statesboro, GA USA
Thanks for the input, I did not know that a 240v photocell only broke one leg. I would have thought it worked as a double pole switch. Thanks

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#85610 - 07/22/03 05:43 AM Re: Photocell code reference
PCBelarge Offline
Member

Registered: 06/08/03
Posts: 657
Loc: Dobbs Ferry, NY, USA
arseegee
I thought like you did. I just called a supplier and he checked 2 different photocell manufacturers. Both showed only one leg being opened. You learn something new everyday!

Pierre
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Pierre Belarge

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#85611 - 07/22/03 01:03 PM Re: Photocell code reference
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
May be worth mentioning that there is a significant difference between control and disconnecting means. A photocell does the first task—it is suicidal to assume it is always intended to do the second.

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#85612 - 07/23/03 04:44 PM Re: Photocell code reference
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6805
Loc: Brick, NJ USA
Learned something topday, and I agree wholeheartedly with Bjarney!!
John
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