Conduit Support

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mull982

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I'm not really sure if this type of question belongs in this section of the forumn but if not hopefully it will be moved to the correct one.

When installing conduit racks the contractor is attaching unistrut to steel Beams. The unistrut is running perpendicular to the beam and extends out from the beam to support the conduit.

They are only using a clamp (window clamp) on one side of the flange on the beam and not the other. My electricians have informed me that there should be clamps on both sides of the flange to support it properly, and the contractor is arguing that only one side is required so therefore a battle has ensued.

What is the propper practice for this application and are there any articles to reference?
 
As far as the NEC is concerned all that matters is it is 'securely fastened' if that takes one, two or more will be up to the inspector.
 
I've seen this done also. The weight of the conduit will force the unsupported end of the strut into the beam. Unless there's an earthquake it can't really go anywhere.
 
infinity said:
I've seen this done also. The weight of the conduit will force the unsupported end of the strut into the beam. Unless there's an earthquake it can't really go anywhere.
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That makes sense. I guess the other things my electricians are concerned about is the strut moving back and forth horizontal to the beam because one end is free and not supported.
 
Window clamps, when fully tightened, hold very well. Add in the rigidity of the conduits strapped tightly to the strut and it really cannot move. Had an old Foreman who only let us put hex nuts on the underside of conduit racks. He always said that "gravity pulls down and that the conduit can't fall up". :rolleyes:
 
tkb said:
If you let go of something and it does not fall, is it supported? :grin:
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When I was a kid, I accidentally let go of a helium balloon.

It wasn't supported, and it fell up. ;)
 
benaround said:
Did you notice on the 'unistrut' site it said, use in pairs only!! 110.3(B)
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I did.:smile:

Thanks for the link Don. Haven't seen those used or stocked around here.
 
Benaround,
I was going to note the same thing. With just one setscrew the unistrut would easily pivot.
 
CAPS said:
Benaround,
I was going to note the same thing. With just one setscrew the unistrut would easily pivot.
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How would it pivot with the conduit strapped to it?
 
I can't see your install from here but if you think it's going to be unsafe have the electrical inspector bust his balls. Tell him the general is doing this part of the install and you feel it's unsafe. More than likely he will back you up.
 
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