Two Circuits to Light Fixture

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hersched

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I have a client who wants to run two circuits to their fluorescent lighting. The light fixtures have (3) lamps with (1) 1-lamp ballast and (1) 2-lamp ballast. They would like to run an emergency power circuit from a generator to the 2-lamp ballast and a normal power circuit to the 1-lamp ballast. This way when there is a power outage they will have at least 2/3 of their lighting to be able to continue operations.

I don't see anything in the code that prohibits this but it doesn't seem like a good idea to me. Someone could kill power to one of the circuits and not realize there is a second circuit that is still live within the fixture.

Is this allowable by code? Has anybody else done this, brought two circuits from seperate panels to a light fixture?
 
Nothing comes to my mind that would prohibit such a installation.

Maybe someone else will chime in with another opinion.

Just curious, how will you ever have two sources of power to the lights at the same time.
From the way you describe the circuit, it will be either POCO power or generator power to the lights, not both.
You plan to use a transfer switch....correct?

steve
 
I see this all the time, and often include it in my designs. If an electrician opens the fixture and sees two separate ballasts, it would be a good practice to presume they are served by separate power sources, until it is proven otherwise. I don't know if there is any requirement to lable the fixture as having two separate sources.

Both sets of lights can be on at the same time, because the panel serving the emergency lights gets power from the utility, when utility power is available.
 
It is a very common practice in the buildings I work in. Just remember the code now requires a disconnect on each fixture [410.73 (g)] and with this arrangement you will need two disconnects.
 
DLTravis said:
It is a very common practice in the buildings I work in. Just remember the code now requires a disconnect on each fixture [410.73 (g)] and with this arrangement you will need two disconnects.
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In the 2008 code its under 410.130 (G) (2), (3).

(2)Multiwire Branch Circuits . When connected to a multiwre branch circuits, the disconnection means shall simultaneously break all the supply conductors to the ballast, including the GROUNDED conductor.

(3)Location. The disconecting means shall be located so as to be accessible to qualified persons BEFORE servicing or maintaining the ballast. Where disconnecting means is external to the luminaire, it shall be a single device, and shall be atached to the luminaire or thel uminaire shall be located within sight of the disconnecting means.
 
'08 410.130 (E) Egress Luminaires. A ballast in a fluorescent luminaire that is used for egress lighting and energized only during a failure of the normal supply shall NOT have thermal protection.

Wording on the Advance site indicates UL 935 <requires> indoor fluorescent ballasts to be thermally protected.

I too have indoor fixtures with 2 UL listed ballasts : 1 normal, 1 generator. My out is the wording in 410.130 applies only to luminaires who emergency ballast is energized ONLY during a failure of normal supply. Generator doesn't have an ATS, so emergency ballast will be energized independant of the normal supply.

I looked back to the 96 code : emer fixtures were an exception to the requirement for class P ballasts; 2002 they became prohibited to have class P. Not sure if the change was intentional or a result of NFPA writing style change.
 
Art 702

Art 702

I think the article you are looking for is in 702.6 paragraph 3 and the exception. The wording "transfer equipment shall be required for all standby systems subject to the provisions of this article..." . By using the wording 'shall' and including your installation under the definitions, I would say you need a transfer switch.
 
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