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I'd like to span a lighting circuit and an appliance circuit across a steel I-beam in a low ceiling garage using a fluorescent fixture:

Lighting + Appliance Circuit ------\   I   /-------- Appliance Circuit
                             ______|___I___|_________
                                 '-----------'

The fluorescent fixture is shown in the above ASCII art attached to the ceiling below the "I" beam.

In a previous question I confirmed that given a light fixture "identified for through-wiring", this is up to code. However, I haven't been able to find any fluorescent fixtures "identified for through-wiring". None of the product literature mentions anything like that. I've seen some that are indicated for end-to-end connection, but I don't think I can put an appliance circuit through one like that.

I don't want this to be a "shopping" post, but can anyone point me to some example product literature for a fluorescent fixture so I and others know what kind of wording to look for?

  • Do you have a local electrical supply shop? If so, they should be able to sell you what you need. – Tester101 Dec 22 '15 at 18:51
  • @Tester101. I can go to Platt. Given my previous experience, I'm not sure if they'd know that I'm talking about. I'll give it a try though. – watkipet Dec 22 '15 at 19:04
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    Can you use a "direct mount" fan box? They are no thicker than sheetrock, but have a space for wire connections. They also make them with cavities on either side of the stud - "saddle box". – JPhi1618 Dec 22 '15 at 19:13
  • @JPhi1618 But how would I attach the saddle box to the I-beam? Aren't they designed to be attached to a wooden joist? This is old-work, BTW. I'll be fishing the wires through the joist cavities. – watkipet Dec 22 '15 at 19:19
  • Sorry, I thought you were just calling it an "I-beam", and I didn't realize it wasn't a wooden stud/joist. We get all languages and odd terms for things - my fault. – JPhi1618 Dec 22 '15 at 19:22
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There should be a stamp/label on the fixture similar to

MAXIMUM OF 8 NO 12 AWG THROUGH BRANCH CIRCUIT CONDUCTORS SUITABLE FOR AT LEAST 90°C PERMITTED IN BOX (4 IN 4 OUT).

Not sure that would be listed anywhere if you're shopping online, as most websites aren't great at describing products. Surely if you went to a physical store, you could inspect the fixture for the marking. You might also be able to find this information on the manufacturer's website, in their catalog, or by contacting them directly.

  • I went to my local big-box store. I didn't find any fluorescent fixtures with wording like that. I'll keep looking around. – watkipet Jan 4 '16 at 23:11
  • I went with some LED fixtures (they look like fluorescent fixtures). They don't have any wording similar to the above. However, it turns out that there's a small gap between the I-beam and the subfloor that I was able to fish the wires through in some areas. – watkipet Jan 27 '16 at 23:46
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You can pass through another lighting circuit through a fixture lister for such use. You cannot pass through something like an appliance circuit.

Will provide the code reference when I get home. NEC 410.64 is the US code section.

410.64 Luminaires as Raceways

Luminaires shall not be used as a raceway for circuit conductors unless they comply with 410.64(A), (B), or (C).

(A) Listed.

Luminaires listed and marked for use as a raceway shall be permitted to be used as a raceway.

(B) Through-Wiring.

Luminaires identified for through-wiring, as permitted by 410.21, shall be permitted to be used as a raceway.

(C) Luminaires Connected Together.

Luminaires designed for end-to-end connection to form a continuous assembly, or luminaires connected together by recognized wiring methods, shall be permitted to contain the conductors of a 2-wire branch circuit, or one multiwire branch circuit, supplying the connected luminaires and shall not be required to be listed as a raceway. One additional 2-wire branch circuit separately supplying one or more of the connected luminaires shall also be permitted.

  • 410.21 states, "Branch-circuit wiring, other than 2-wire or multiwire branch circuits supplying power to luminaires connected together, shall not be passed through an outlet box that is an integral part of a luminaire unless the luminaire is identified for through-wiring." So, I'm talking about running branch-circuit wiring that doesn't supply power to luminaries. I can't do that unless the fixture is identified for through-wiring. That's why I'm looking for a fluorescent fixture identified for through-wiring. – watkipet Dec 22 '15 at 22:40
  • Even if you find one for through wiring it can only be for supplying power to luminaires (light fixtures). – Speedy Petey Dec 22 '15 at 22:41
  • 410.21 refers mainly to recessed lights with junction boxes, while 410.64(C) clearly describes fluorescent strips. – Speedy Petey Dec 22 '15 at 23:01
  • @SpeedyPetey -- he's looking for a fixture that meets 410.64(A) or 410.64(B), not 410.64(C) -- in his case, the integral junction box must also meet 410.21, but 410.64(C) is not what he's after. – ThreePhaseEel Dec 22 '15 at 23:10
  • But he is looking for a fluorescent fixture. Pretty much meets (C) to a T, no? – Speedy Petey Dec 22 '15 at 23:12

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