Surface Mounted Fixtures

[Alwayslearningelec]

These are surface mounted to concrete slab feed with EMT. Regarding boxes and feeding you could do the following ways( not including EM's). Can't use FMC to tail to fixtures.

1. 4" box next to each fixtures
2. 4" box between a few fixtures and branch off
3. Could you go directly in/out of the fixtures with the EMT with no boxes? THat would require splicing in the fixtures which may not be allowed???

 

[infinity]

You can run EMT from fixture to fixture. Most guys use a box next to the fixture connected with an offset nipple but if you're just going in and out in a row the box isn't needed unless you plan on carrying other circuits through the raceway.

 

[ActionDave]

3. Could you go directly in/out of the fixtures with the EMT with no boxes? THat would require splicing in the fixtures which may not be allowed???

It is allowed for circuits that power the lights. 410.64(C)

 

[Alwayslearningelec]

You can run EMT from fixture to fixture. Most guys use a box next to the fixture connected with an offset nipple but if you're just going in and out in a row the box isn't needed unless you plan on carrying other circuits through the raceway.

Thank you. SO the reason for the box would only be to pull different circuits through? If you have 8 4' surface lights all on same circuit there's no need for box and you could just go in and out of fixture with EMT? There's no code, even NYC, that prohibits splicing in the fixture?

 

[Alwayslearningelec]

It is allowed for circuits that power the lights. 410.64(C)

Oh just saw after I posted. Thank you.
It does say a 2 wire circuit and a MWBC.

 

[mtnelect]

That's how I do it ... First use Steel Strut (Kindorf) channel hung with all thread. Then fixtures attached to strut with EMT in-between.

 

[Alwayslearningelec]

That's how I do it ... First use Steel Strut (Kindorf) channel hung with all thread. Then fixtures attached to strut with EMT in-between.

??? . If the 4' fixture is surface mounted against the concrete ceiling why wouldn't you run the conduit tight to the slab or maybe on strut right into the fixture so you don't have to offset? Why would you hand the fixture the way you said? Anyway of the drawing/architect calls for it to be surface mounted on the slab then it should be.

 

[infinity]

??? . If the 4' fixture is surface mounted against the concrete ceiling why wouldn't you run the conduit tight to the slab or maybe on strut right into the fixture so you don't have to offset? Why would you hand the fixture the way you said? Anyway of the drawing/architect calls for it to be surface mounted on the slab then it should be.

I think he's just giving an alternate method.

In your installation you can attach to the slab above and pipe from fixture to fixture. You probably have some old timer tell you that you can't do it that way but they would be wrong.

Years ago branch circuit wiring wasn't rated for 90° C so it couldn't go through the fixture. Modern THHN doesn't have that problem.

 

[Alwayslearningelec]

I think he's just giving an alternate method.

In your installation you can attach to the slab above and pipe from fixture to fixture. You probably have some old timer tell you that you can't do it that way but they would be wrong.

Years ago branch circuit wiring wasn't rated for 90° C so it couldn't go through the fixture. Modern THHN doesn't have that problem.

Ahhhh interesting regarding the insulation

 

[Rick 0920]

If the fixture is listed for use as a raceway, thru-wiring is permitted.

 

[mtnelect]

I think he's just giving an alternate method.

In your installation you can attach to the slab above and pipe from fixture to fixture. You probably have some old timer tell you that you can't do it that way but they would be wrong.

Years ago branch circuit wiring wasn't rated for 90° C so it couldn't go through the fixture. Modern THHN doesn't have that problem.

Thank You ... I forgot to mention, that this was for commercial / Warehouse installations with open beams.

 

[Alwayslearningelec]

If the fixture is listed for use as a raceway, thru-wiring is permitted.

So ultimately even through the wire insulation is 90 and can splice in fixture you must check the fixture to see if thru wiring is allowed? All fixture cut sheets should address this?

 

[infinity]

So ultimately even through the wire insulation is 90 and can splice in fixture you must check the fixture to see if thru wiring is allowed? All fixture cut sheets should address this?

There is a code provision that allows you to pull additional circuits through the fixture if it is designed and listed as a raceway (you're literally using the interior of the fixture as a raceway). If you're just connecting them together on one circuit you do not need that type of fixture.