roofing

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mcelweec@gmail.com

CMAC1
Location
NYC
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Electrician
i have a 1200a and 2 1600a feeders to run across a flat roof approx 100 ft.i am considering using 3 outdoor wireways to run the feeders.has anyone any experience with this type of install,in particular i would like to know how to handle the roof penetrations.
 
I would think the penetrations would be the least of my worries.
It's the heat build up in the wire ways, raceways, etc...that can be a problem.:wink:

But back to your OP, (penetrations) simple sub that part out to a qualified roofer. Or don't include that part in your contact.
 
Often there is an ongoing warranty for the roof and all penetrations will need to be done as directed by the roofing manufacturer. In other words .... sub it out.

If your under the 2008 NEC there are new rules in place that requirer some serious derating of conductors run on roofs.
 
it's not the penetration itself that worries me ,it's sealing the wireway lid that i'm concerned about.heating of the conductors does worry me.has anyone used pvc wireways outdoors for this type of install,if so what do i need to lookout for.btw there would be less than 30 cccs per wireway.
 
Agreed. I would let the roofer take care of the penetrations.

Don't forget to de-rate the conductors per 310.15(B)(2)(c). If you're still in 2005 code, then this is not necessary.

B-Line makes some pretty handy rooftop supports. I've used them before, and they make for a really quick install. http://www.b-line.com/Dura-Blok/index.asp

Also, you might want to check with the building engineer or building inspector about using the roof to support that much weight. 1200A and 1600A circuits are going to be pretty heavy.

Be especially sure to keep in mind how you are going to pull the wire when you are designing the pipe installation. You don't want to be hauling wire tuggers up to the roof.
 
just checked out 225.10,i see no problem with using wireway.My main concern with using individual conduits is pulling wires as mark pointed out
 
If you run it in PVC, make sure to account for your expansion fittings. 100 ft of PVC would need at least one per run here in NC. These can get pretty expensive for the bigger size pipe. Also factor in that your PVC runs are going to be supported every 6 or 7 ft instead of every ten ft. It might actually be cheaper to go with IMC / Rigid / EMT.
 
mcelweec@gmail.com said:
i have a 1200a and 2 1600a feeders to run across a flat roof approx 100 ft.i am considering using 3 outdoor wireways to run the feeders.has anyone any experience with this type of install,in particular i would like to know how to handle the roof penetrations.
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Usually have building owners roof guy seal penetrations to not void his warranty.
A leak can do lots of damage on a flat roof.
I will tackle resi pitched roof because I was taught how by a couple of roofers and have done quite a few complete installs.
I wont do anything over a 5 pitch because I am getting too old to withstand a fall off a roof.
Good money in roofing. Bad liability in roofing.
I usually only poke a mast through when needed now.
 
my main reason for posting this was to get a feel to whether or not to use a trough on a roof.Sealing the roof is not my concern,making the trough watertight is.
 
Just my opinion but the tugger can do a lot more work then I can in a day and laying that wire in a trough is no picnic.
 
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