PVC and strut straps....

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emahler

Senior Member
Just had an inspector ask us to replace T&B 702 rigid strut straps with 2 Hole Carlon PVC straps...

situation is parallel 2 1/2" PVC conduit risers...unistrut mounted on the wall, and the 702 Rigid strut straps securing them.

he is requesting that we remove the strut straps, and install regular carlon 2 hold straps, using spring nuts to secure them to the strut...

anyone come across this? any new product(s) on the market?
 
don_resqcapt19

don_resqcapt19

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Location
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retired electrician
352.30 Securing and Supporting.
PVC conduit shall be installed as a complete system as provided in 300.18 and shall be fastened so that movement from thermal expansion or contraction is permitted. PVC conduit shall be securely fastened and supported in accordance with 352.30(A) and (B) or permitted to be unsupported in accordance with 352.30(C).
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Standard straps do not permit the required movement of the PVC.
 
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satcom

Senior Member
emahler said:
can you elaborate? standard strut straps? or standard PVC straps?
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Strut straps do not permit the movement, even inside a building you have movement, if you come thru town, give me a call, and I can show you some jobs with the PVC straps.
 
tonyou812

tonyou812

Senior Member
Location
North New Jersey
I always use PVC with PVC. And I might even be the only EC that uses expansion fittings in all of NJ.
But do you really think that uni strut and metal straps look better than the proper PVC strap? Besides PVC straps are a lot faster and a little cheaper to install then uni strut.

IMO you are overthinking the whole thing and overlooking the listing on the straps. Im pretty sure the straps arent listed for PVC. They usually have EMT or RMC engraved on them anyhoo so the inspector has got you there.
 
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satcom

Senior Member
"And I might even be the only EC that uses expansion fittings in all of NJ."

No, I clean up a lot of jobs missing expansion fittings too, I sent him a Picture of 2 1/2 PVC installed with the plastic straps.
 
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wawireguy

Senior Member
Unfortunately I've never installed a expansion fitting.. And I live in the NW. Trust me it's not by choice..
 
kbsparky

kbsparky

Senior Member
Location
Delmarva, USA
Here are some straps that we commonly use for PVC. A whole lot easier and quicker than 2-piece kindorf straps.

Strut optional ... :D

Pipe%20Hangers.jpg
 
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emahler

Senior Member
in this case we have parallel 2 1/2" PVC risers, approx 15' long, straight up the exterior of the building. Each riser contains 4 - #3/0 copper conductors

I'm clear up top, so expansion/contraction is not an issue.

the strut straps, if installed correctly, will allow the PVC to move up and down, just as well as the straps.

it's definitely quicker to install strut when you are paralleling risers.

the main concern is that the PVC straps will weather and become brittle (sp?) and fail if there is any pressure on them...it's not uncommon in these parts...

these particular straps (T&B 702) are rated for "Rigid/IMC conduit and pipe" and a quick phone call to Susan Borak at the DCA confirmed that there is no official DCA ruling and that her interpretation is that the PVC is actually Rigid Conduit, and that the installation is acceptable.

sent an email with the cut sheet to the inspector, so we'll see what happens....
 
JacksonburgFarmer

JacksonburgFarmer

Senior Member
Location
Butler County Ohio
I belive there are plastic strut staps availiable for PVC....seems like in a steel mill once on a "pickle line" (crappy place to be....trust me) we used them on
2" PVC, with fiberglass unistrut.....that was a craphole job....
 
don_resqcapt19

don_resqcapt19

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Location
Illinois
Occupation
retired electrician
emahler said:
in this case we have parallel 2 1/2" PVC risers, approx 15' long, straight up the exterior of the building. Each riser contains 4 - #3/0 copper conductors

I'm clear up top, so expansion/contraction is not an issue.
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In my area that could result .75" of movement from summer to winter assuming that it is in the sun in the summer.

the strut straps, if installed correctly, will allow the PVC to move up and down, just as well as the straps.
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I don't see how rigid conduit strut straps, correctly installed, permit this movement.

it's definitely quicker to install strut when you are paralleling risers.
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No question about that.

the main concern is that the PVC straps will weather and become brittle (sp?) and fail if there is any pressure on them...it's not uncommon in these parts...
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I have the same concern with the conduit itself.
 
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