Lights as raceways - NEC 410.62

[Deude_Mann]

So I have been researching on whether using a light fixture as a raceway is allowable via code. In doing so I found this thread:

https://www.garagejournal.com/forum/showthread.php?t=138338&highlight=410.64

Note that this thread seems to conclude that it is OK, but it is from 2012 so I do not know if the code is still the same.

Of course there are several web pages discussing 410.64, but most just indicate to check 410.62 (C). In addition, the more I read, the more opinion and confusion I see.

So here is my question. If I have four light fixtures in series, let's say all with knockout plugs on the ends, If I use all 12/2 MC for example, and use strain relief clamps at the inlet and exit of each fixture, can I hardwire all of the fixtures together in series, using the wiring space within the fixture as the junction box? All of the wiring would be visible which is another thing discussed in the code.

It would look like...

switch <--MC--> Luminary 1 <--MC--> Luminary 2 <--MC--> Luminary 3 etc. etc.

Instead of

switch <--MC--> junction box <--MC--> junction box <--MC-->
.........................Luminary 1..................Luminary 2


I understand that it would make fixture removal more of a PIA but in today's world of highly reliable, long-life LED fixtures I am not too concerned about it. All the junction boxes seem like overkill as well, and waste more of the expensive 12/2/2. That stuff is expensive, about $1.10 a foot.

Thanks

 

[u2slow]

In my experience, a fixture (luminaire) that allows this will be marked "suitable for row mounting" or similar, and will have knockouts in the ends for connecting them with lengths of conduit or bushings.

EDIT: #12 circuits are usually excessive for lighting, especially LED.

 

[Deude_Mann]

EDIT: #12 circuits are usually excessive for lighting, especially LED.

Right I agree. I think all of them combined only use 800W or so. That combo wire comes in 12/2/2 though. It's really expensive but sure makes the wiring easier (with the dimmer).


EDIT: Correction, there is a 14/2/2 MC and it is a lot less expensive, though not intended for low voltage? But then again, what difference would it really make? It's just overkill.
https://www.cablecabana.com/shop/re...-mApntQ3ywUrwUzM7TS8EblKc5X7HLZhoCfqAQAvD_BwE

 

[Deude_Mann]

Here is the 12/2/2 which is specifically intended for light/dimmer combo runs.
https://www.homedepot.com/p/Southwi...r-and-Control-Signal-Cable-59225101/303654305

 

[u2slow]

JMHO, but I would use EMT and pull in conductors. Looks real tidy for the minimal strapping needed. EGC/bond wire not required either.

 

[Deude_Mann]

JMHO, but I would use EMT and pull in conductors. Looks real tidy for the minimal strapping needed. EGC/bond wire not required either.

I considered that... seems like it would be a lot of work with 8 fixtures? Though I have not used EMT much at all really so I cannot speak from experience.

Those fixtures do have end knock out plugs though, so maybe internally it is a straight shot pull once all of the EMT is in place (for each set of 4). It's these guys....
https://greenlightdepot.com/product...-mounting-gen-5-ul-dlc?variant=16980078755883
I do not see anything about "suitable for row mounting" on the fixture or in the installation guide.

OK dumb question... To meet code, would the EMT have to be hard pipe or could it be flex, which I guess flex would be like MC without any wiring in it. A combo of the two would make the installation easier.

 

[wyliesdiesels]

Right I agree. I think all of them combined only use 800W or so. That combo wire comes in 12/2/2 though. It's really expensive but sure makes the wiring easier (with the dimmer).


EDIT: Correction, there is a 14/2/2 MC and it is a lot less expensive, though not intended for low voltage? But then again, what difference would it really make? It's just overkill.
https://www.cablecabana.com/shop/re...-mApntQ3ywUrwUzM7TS8EblKc5X7HLZhoCfqAQAvD_BwE

That 14/2/2 NM-b (its not MC) that you linked to is NOT for LED dimmer circuits. Its for AFCI circuits.

The one you linked to with the MC is the correct cable.

 

[Deude_Mann]

Would it be OK per code to use the 14/2/2 for a dimmer circuit? If anything the extra conductors would be big time overkill for the 0-10V signal as far as current load. Or is there something else about the 12/2/2 (that I linked to) that makes it more appropriate?

From what I can tell, the 12/2/2 low voltage wires are not shielded or twisted, or anything like that.

 

[u2slow]

OK dumb question... To meet code, would the EMT have to be hard pipe or could it be flex, which I guess flex would be like MC without any wiring in it. A combo of the two would make the installation easier.

EMT (electrical metallic tubing) is a thinwall metal conduit - not flex. Flex may not be an adequate ground path... not sure what NEC says.

I thought you meant the fixtures were ceiling mounted. If they are chain-hung, then I'd pipe (EMT) the ceiling with JB's at approx every 2nd fixture and run a whip of AC/MC down the chain to each. Leave a little extra whip length, and then you have the freedom to fine-tune their position and height as you use and populate your shop.

 

[Deude_Mann]

EMT (electrical metallic tubing) is a thinwall metal conduit - not flex. Flex may not be an adequate ground path... not sure what NEC says.

Yes sorry I do not know all of the proper terminology for electrical work. It is like sailing language (which I know) full of weird nouns, verbs, and terms.

I know EMT is rigid wall, but there would be some spots where it would be a lot easier not to have to bend it and make everything line up exactly, so I'd use this stuff.
https://www.homedepot.com/p/Southwi...-Aluminum-Flexible-Conduit-55082103/202316476

Being able to go back and forth between the two as needed would be helpful.

I could mount the lights rigidly but since the underside of the purlins are tilted at an angle (roof pitch) then the lights would end up that way as well, unless I adapted the mount somehow. It's a metal building that will not have a rigid ceiling, just laminated batt insulation.

 

[Deude_Mann]

I thought you meant the fixtures were ceiling mounted. If they are chain-hung, then I'd pipe (EMT) the ceiling with JB's at approx every 2nd fixture and run a whip of AC/MC down the chain to each. Leave a little extra whip length, and then you have the freedom to fine-tune their position and height as you use and populate your shop.

I think I am following what you are getting at here. So it would be something like...

<---EMT---><JB><------------EMT--------------><JB><---EMT--->
............Light^^Light................................Light^^Light
etc. etc.

^ would be the connection from the light to the JB via MC.

 

[u2slow]

Ahhh... I assumed you had a flat ceiling surface to work with. You may be better to keep it all in cable then.

I'm not up on NEC particulars - others will likely chime in.