EMT mounted to roof underside

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sevlander

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Can anyone tell me if and where the NEC forbids running EMT in the top groove of the underside of corregated metal sheet roofing. I know new jersey inspectors have failed jobs recently. Is it in the NEC? Thanks
 
No it's not in the nec, as long as it is not a corrosive enviroment. In 08 their are some issues with derating the current carrying conductors in roof top metal conduits.
IMHO
 
There is a new 2008 NEC code section that prohibits this. Take a look at 300.4(E). Here is what this section says:

(E) Cables and Raceways Installed Under Roof Decking. A cable- or raceway-type wiring method, installed in exposed or concealed locations under metal-corrugated sheet roof decking, shall be installed and supported so the nearest outside surface of the cable or raceway is not less than 38 mm (1? in.) from the nearest surface of the roof decking.
FPN: Roof decking material is often repaired or replaced after the initial raceway or cabling and roofing installation and may be penetrated by the screws or other mechanical devices designed to provide ?hold down? strength of the waterproof membrane or roof insulating material.
Exception: Rigid metal conduit and intermediate metal conduit shall not be required to comply with 300.4(E).

Chris
 
Exactly what I Needed

Exactly what I Needed

Thanks,I knew it had come up before, just couldn't figure out where.
N.J. has not yet adopted 2008,but I think inspectors are already looking at this.
 
As NJ has yet to adapt the '08 NEC, I am curious as to what particular article in the '05 they cited on the red tag.

Do you know?
 
I saw guys put on a new roof and ran a screw right down through a piece of emt that was at least 1-1/2" away. Wouldn't have believed it possible, if I hadn't a seen it.

You'd think they'd have gone with the 14" screws instead of the 20"

(just kidding ... but they were way too long and you'd think they'd a cost more ):smile:
 
raider1 said:
There is a new 2008 NEC code section that prohibits this. Take a look at 300.4(E). Here is what this section says:

(E) Cables and Raceways Installed Under Roof Decking. A cable- or raceway-type wiring method, installed in exposed or concealed locations under metal-corrugated sheet roof decking, shall be installed and supported so the nearest outside surface of the cable or raceway is not less than 38 mm (1? in.) from the nearest surface of the roof decking.
FPN: Roof decking material is often repaired or replaced after the initial raceway or cabling and roofing installation and may be penetrated by the screws or other mechanical devices designed to provide “hold down” strength of the waterproof membrane or roof insulating material.
Exception: Rigid metal conduit and intermediate metal conduit shall not be required to comply with 300.4(E).

Chris
Click to expand...

Here is an illustration.

http://i125.photobucket.com/albums/p66/JohnJ0906/Dillons/screwinconduit.jpg

http://i125.photobucket.com/albums/p66/JohnJ0906/Dillons/HPIM0247.jpg
 
sevlander said:
Thanks,I knew it had come up before, just couldn't figure out where.
N.J. has not yet adopted 2008,but I think inspectors are already looking at this.
Click to expand...

As far as I know NJ is still under the 2005 NEC. So an inspector cannot enforce a 2008 NEC requirement. They might want to tell the EC of the coming code change but they cannot issue a red tag for still installing it without the required 1.5" space.
 
i see that stuff all the time. i dont understand why people want to run emt up that close to the celing when they drive in those long screws. i had to repair a few of these pipes with long screws through them
 
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