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#75484 - 02/27/07 03:39 PM stell bar joist
sudsy4 Offline

Registered: 04/24/02
Posts: 32
Loc: Elizabeth,PA USA
Does anyone know of any requirements as to where or where not to attach conduit to steel bar joists?

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#75485 - 02/27/07 05:27 PM Re: stell bar joist
Peter Offline

Registered: 06/08/04
Posts: 93
Loc: San Diego
It might be a specification issue. I have been on jobs that seemed to say "Do not install conduit on top of the bottom bars." But I have no idea why.
On other jobs, anything goes.
However, if you are running conduit parallel to the joist, it is wise to run them along side instead of on the bottom. The reason being that sometime later, someone may have to run another conduit perpendicular to the bar joists along the bottom and the bottom should be clear for this.
Also it is inadvisable to run conduit above the joists in the roof corrugation since it would be vulnerable to damage by the roofer's long screws.

#75486 - 02/27/07 08:43 PM Re: stell bar joist
stevecheyenne Offline

Registered: 11/29/06
Posts: 38
Loc: Yorba Linda, CA
It does seem to vary by job, but if it's a hassle you can generally get the requirement to stay off of the lower bar waived. Just ask the owner if he wants you to testify as part of the lawsuit - the lawsuit against the structural engineer who designed a roof so flimsy it couldn't stand the additional load of a conduit, much less a replacement roof.

It's amazing how much stronger those joists get when you do that.

#75487 - 02/28/07 05:03 AM Re: stell bar joist
Luketrician Offline

Registered: 07/08/06
Posts: 273
Loc: Sale Creek, TN USA
Few years ago, I was running some 3/4 homerun conduits and the GC told me that I needed to run all of my conduits as close as possible to the weld points of the bar joists. I told him that may be true for hanging transformers, bussduct or other types of heavy equipment, but not for EMT.
Luke Clarke
Electrical Planner for TVA.

#75488 - 02/28/07 04:29 PM Re: stell bar joist
iwire Offline

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
It is a common job specification for us not to use the bottom cord for support.

Always read your specs.
Bob Badger
Construction & Maintenance Electrician

#75489 - 02/28/07 06:02 PM Re: stell bar joist
renosteinke Offline
Cat Servant

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
I have not run into the "don't use" spec ... but, thanks to this forum, I'll add it to my list of things to be careful about!

FWIW. I do try to avoid running screws into such things; I use beam clamps instead.

Thx, Iwire!


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