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

[Jason Szumlanski]

Never had a problem with PVC on flat roofs when supported properly and
proper expansion fittings are used (and directions followed explicitly).
PVC expands/contracts about 4 inches for every 100 ft of pipe for a 100
degree F change. It's critical to know the temperature when you are
doing the installation and figure out where that falls in your
temperature range window. Since it rarely gets much below freezing in
Southwest Florida, the temperature window here may be smaller than some
of you experience, but I've never had to use more than one or two
expansion fittings in a straight run of pipe (good route planning is
helpful).

 

I've never been a big fan of long conduit runs on the roof anyway (get's
pretty hot here on roofs). Ideally we get into the building as soon as
possible.

 

How does the Rubber Triangle Co product price compare to Durablock?
Those things can be expensive! Another reason to get inside the building
quickly...

 

Jason

 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Glenn
Burt
Sent: Thursday, December 22, 2011 1:21 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Expansion on conduits on commercial roof
tops!

 

If you are talking about commercial flat roofs, we never use PVC - too
much expansion potential.

All our rooftop conduit runs here in the Albany, NY area are RMC of the
galvanized type, and of course, threaded. 

There are standard plumbing supports with rollers, as well as standard
expansion fittings (be sure to match the fitting to the conduit - don't
use EMT with RMC unless approved by the manufacturer).

A great product we have recently begun using is a EPDM pipe support by
the Rubber Triangle Company that is compatible with most rubber roofing,
and allows a lot of movement.

 

-Glenn

 

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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