Branch Circuit Conduit on a Roof

[Shujinko]

For a building roof application, where in the code does it say that a branch circuit conduit has to have clearance below it for re-roofing? I thought I saw in code a long time ago that a branch circuit conduit can be mounted on the roof surface but has to have 1' clearance below it (min) for re-roofing purposes. The conduit run would have to be mounted on a 1' pedestal. IS this in the NEC or is this in another code? I can't seem to track down where I found this. Please help!:?

 

[infinity]

Are you referring to running the conduit on or under the roof? For on the roof there is no minimum, for under there is a 1.5" spacing requirement except for RMC.

 

[rcarroll]

300.4(E)

 

[infinity]

300.4(E)

I agree that would apply for under the roof but his thread title is "on a Roof".

 

[rcarroll]

I agree that would apply for under the roof but his thread title is "on a Roof".

You're right. I mis-read his question. :ashamed1:

 

[petersonra]

For a building roof application, where in the code does it say that a branch circuit conduit has to have clearance below it for re-roofing? I thought I saw in code a long time ago that a branch circuit conduit can be mounted on the roof surface but has to have 1' clearance below it (min) for re-roofing purposes. The conduit run would have to be mounted on a 1' pedestal. IS this in the NEC or is this in another code? I can't seem to track down where I found this. Please help!:?

it's not for reroofing. If you lay the conduit directly on the roof you have to adjust the ampacity for ambient temperature more than if you raise it up off the roof.

310.15 (B)(3)(c)

 

[infinity]

it's not for reroofing. If you lay the conduit directly on the roof you have to adjust the ampacity more than if you raise it up off the roof.

Yes there's that debacle.

He's saying 1 foot, the 2017 NEC only requires it to be raised 7/8" to eliminate the derating.

 

[petersonra]

Yes there's that debacle.

He's saying 1 foot, the 2017 NEC only requires it to be raised 7/8" to eliminate the derating.

maybe he meant 1" instead of 1'.

 

[infinity]

maybe he meant 1" instead of 1'.

You might be right, 1' would be pretty high and create a nice tripping hazard but 1" won't do much for re-roofing.

 

[petersonra]

You might be right, 1' would be pretty high and create a nice tripping hazard but 1" won't do much for re-roofing.

even if it was a foot the supports would have to go down to the roof anyway.

 

[Shujinko]

You might be right, 1' would be pretty high and create a nice tripping hazard but 1" won't do much for re-roofing.

I will look in the IBC because I think it's in there and I think the requirement is alot higher than 1".

 

[infinity]

I will look in the IBC because I think it's in there and I think the requirement is alot higher than 1".

Could be but I've never heard of it. As far the NEC is concerned above 7/8" and no special rules apply.

 

[augie47]

Could be but I've never heard of it. As far the NEC is concerned above 7/8" and no special rules apply.

Which I find fascinating. For the past decade we worried with ANSI temperatures, distances off the roof, etc and a bunch of jobs here were rejected. Now, all of a sudden, 7/8" is the manic number. NO calculations, no sweat.

 

[infinity]

Which I find fascinating. For the past decade we worried with ANSI temperatures, distances off the roof, etc and a bunch of jobs here were rejected. Now, all of a sudden, 7/8" is the manic number. NO calculations, no sweat.

First we were allowed XHHW-2 at any height above the roof without derating (2014), now we're at 7/8" of an inch for any insulation type (2017). How did the CMP screw this up? :roll: