emt support light

[normbac]

I am on a commercial project the plans call for me to hang conduit from a celing jbox
to a jbox which is to be used to support a pendant light. I would need to hang 5ft of conduit from celing and float a 4s box then install fixture on jbox. I have always thought it was not permissable to support anything from conduit. Is this application seem code compliant. TIA

 

[jumper]

While certain conduits may support fixtures and such under the right conditions, EMT cannot.

358.12(5) For the support of luminaires or other equipment except
conduit bodies no larger than the largest trade size
of the tubing.

 

[ActionDave]

You are correct you can't support anything from the conduit.

I don't understand the need to go from a box to a box and then the pendant light. I do know they make adapters for a 4s box that allow you to screw in a stem of RMC to make a pendant light.

 

[jusme123]

 

[jusme123]

Section 314.23(H)(2)

 

[TNBaer]

View attachment 8483

I think that's a TnB product, if memory serves.

 

[TNBaer]

I think that's a TnB product, if memory serves.

Oh, and by TnB I don't mean "Me."

 

[jeremysterling]

View attachment 8483

At one site, the screw slot in the 4-sq cover bent and the light fell. Next to it, the 8-32 screw broke and the light fell. And yet another, the 8-32 tapped ear of the 1900 box broke off and the light fell.

If you use those, use good quality safety chains or aircraft cable.

I drilled 1/4" holes through the pictured hanger, through the box and building purlin and ran two 1/4' by 3" bolts to secure the luminaires from falling again

 

[normbac]

Am I reading correctly that a jbox with knockouts is prhibited form suspending to hang a luminaire. So even allthread would not be a permissable support. If so then the only application for this would be rigid to a threaded jbox?? TIA Can anyone give examples of how to do this most cost efective. There are twentynine 48 inch pendants that need to be hung from a wood joist ceiling that varies from 16 to 18ft. high bottom of pendant is 10 ft A.F.F. Any input is appreciated

 

[jusme123]

Am I reading correctly that a jbox with knockouts is prhibited form suspending to hang a luminaire. So even allthread would not be a permissable support. If so then the only application for this would be rigid to a threaded jbox?? TIA Can anyone give examples of how to do this most cost efective. There are twentynine 48 inch pendants that need to be hung from a wood joist ceiling that varies from 16 to 18ft. high bottom of pendant is 10 ft A.F.F. Any input is appreciated

..........

 

[jusme123]

Am I reading correctly that a jbox with knockouts is prhibited form suspending to hang a luminaire. So even allthread would not be a permissable support. If so then the only application for this would be rigid to a threaded jbox?? TIA Can anyone give examples of how to do this most cost efective. There are twentynine 48 inch pendants that need to be hung from a wood joist ceiling that varies from 16 to 18ft. high bottom of pendant is 10 ft A.F.F. Any input is appreciated

1. from the measurements you gave, the pendants are going to be 6' to 8' if you want at 10' AFF

2. what are you hanging lights, exit signs?

3. what is the weight of the fixture?

 

[normbac]

15 lb light fixture is 48 in long I need to go from 18 ft ceiling to floating jbox then hang fixture fixture bottom needs to be at 10 ft AFF

 

[jusme123]

...look up the manufacture of the lights, some sell kits that attach to light specifically for pendants mounts.

 

[normbac]

...look up the manufacture of the lights, some sell kits that attach to light specifically for pendants mounts.

The fixtures have a canopy that mount directly to a jbox my concern was code requiremts for
hanging jbox to meet the height I need

 

[jusme123]

...why not mount a threaded bell box to the fixture and conduit out of that to a swival cover on JB at ceiling height?

 

[ActionDave]

The fixtures have a canopy that mount directly to a jbox my concern was code requiremts for
hanging jbox to meet the height I need

...why not mount a threaded bell box to the fixture and conduit out of that to a swival cover on JB at ceiling height?

That is the way I would do it. I can't think of any other way at the moment. I know you can't rely on lock rings to hold up the fixture.
It seems odd to me the a commercial light fixture does not have its own provision for a threaded rod.

 

[normbac]

...why not mount a threaded bell box to the fixture and conduit out of that to a swival cover on JB at ceiling height?

I have requested clarity from architect and am waiting on reply. I wanted to have as much code knowledge as possible when he replied. I bid the job as shown on plans and now that i am on the job I realized this is not code compliant. After looking closer it says conduit to jbox with no mention of type, so I am probably going to have eat it on 29 ball joints and RMC Since ceiling varies on height I assume I will have to
cut and thread RMC ??

 

[ActionDave]

Since ceiling varies on height I assume I will have to cut and thread RMC ??

'fraid so. I just did a similar job last year. The good news is after the first three you get all the kinks worked out and you can go into assembly line mode.

 

[normbac]

'fraid so. I just did a similar job last year. The good news is after the first three you get all the kinks worked out and you can go into assembly line mode.

Do you know of any jbox that I could use allthread to and just bend emt off ceiling to jbox

 

[ActionDave]

Do you know of any jbox that I could use allthread to and just bend emt off ceiling to jbox

You can support a box with all-thread, you just can't support a box with fittings and/or lock nuts.