[RE-wrenches] Expansion on conduits on commercial roof tops!

[Darryl Thayer]

Hi all when I started electrical work early 1950s I was taught that any long run on roof had to have a 90 degree bend in it and the wire had to have free space in the box to move in and out of a box.  I do not know if it is valid but I was taught that the short leg of the run should be about 10% of the length of the long stright side.  I love metal conduit, I do not like plastic, but you might say i am old school.
DT
 

________________________________
 From: Hans Frederickson <hans at fredelectric.com>
To: 'RE-wrenches' <re-wrenches at lists.re-wrenches.org> 
Sent: Friday, December 23, 2011 11:31 AM
Subject: Re: [RE-wrenches] Expansion on conduits on commercial roof tops!
 

You just need to keep your strut straps loose enough that the conduit will slip as it expands and contracts. Sometimes you’ll need to use the next size bigger strap from the conduit you’re using. Then make sure you strap the barrel of the expansion coupling tight, and remember to leave enough slack wire in your boxes and conduit bodies to allow for conduit expansion to pull on the wire a bit without stressing wire terminations. That’s it. The Carlon guide for installing their PVC parts covers this stuff pretty well:
http://www.carlon.com/Installation_Training/IT-ISEXPJT.pdf
 
Regards,
-Hans
 
From:re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of James Rudolph
Sent: Friday, December 23, 2011 5:53 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Expansion on conduits on commercial roof tops!
 
Thanks fellas,
I guess I was not clear. We are using RMC or IMC on all of are roof top runs with the appropriate expansion fittings. I am trying to figure out how to deal with the movement of the conduits at the bases where we strap it down to the base( a curb with a small peice of shallow b-line placed on it (4') ).
On Thu, Dec 22, 2011 at 12:06 PM, Jason Szumlanski <Jason at fafcosolar.com> wrote:
PVC conduit? Search for “Carlon PVC Expansion Fittings.”
 
They publish a good PDF that shows when expansion fittings are required and how to install them properly.
 
Jason Szumlanski
Fafco Solar
 
 
From:re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of James Rudolph
Sent: Thursday, December 22, 2011 9:39 AM
To: RE-wrenches
Subject: [RE-wrenches] Expansion on conduits on commercial roof tops!
 
Howdy Wrenches,

I was wondering how everybody is dealing with expanding conduits on roof tops? Do we have an accepted best practice on this?. What I am really looking for is a way to starp long conduit runs on commercial rooftops in direct sun that allow movement and expanision joints to do thier job.

Mahalo in advance!



James B Rudolph
NABCEP Certified PV Installer 

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-- 
James B Rudolph
NABCEP Certified PV Installer


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