PVC and strut straps....

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iwire

iwire

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Location
Massachusetts
Pipe%20Hangers.jpg


For what it is worth an electrical contractor wired a local mall parking garage with RMC and used these plastic quick clips to support the RMC. Its now about 5 years old and the only thing holding the conduit up now are the boxes and the holes through the cement ribs.

Just because a product is listed for the purpose does not make it the right choice for the installation.
 
jjhoward

jjhoward

Senior Member
Location
Northern NJ
Occupation
Owner TJ Electric
Expansion joints R us

Expansion joints R us

We use expansion joints regularly. I actually get a kick out of reveiwing the tables to see how much that damn PVC will expand/contract over temp.

We all had an aaa-haa moment one sunny spring morning.
It had been very cold at night with a frost, but the sun was blazing in the AM on the side of the house with a 25' foot run of 2" PVC. We could hear the PVC straining against the straps and the siding as it expanded.

I liked it. I not sure if my guys appreciated it as much as me :)

I guess it could have been the vinly siding making noise, but I convinced myself it was the conduit.
 
C

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
ptonsparky said:
With prior approval from the local inspector, I cut short pieces of a larger conduit then sllip these over the pvc. Secure the short pieces with strut straps and let the riser expand and contract all it wants. Saves on the expansion fitting as well.
Click to expand...

I like this idea! It sounds like a great way to handle expansion issues with no worries about cheesy pvc straps breaking.
 
GUNNING

GUNNING

Senior Member
Location
Gainesville, Florida
straps?

straps?

I'm confused. If the inspector was asking for expansion fittings then why the stappage question. I found the Carlon guide to expansion fittings. Its really informative. Whats the average extreme temperature differences and it will give you the shrinkage of the pipes. It also does say to loosely strap when using the fittings but I'm a firm believer in a tight pipe install. I hate to see those PVC pipe runs that look like waves on the ocean.

SO whats the shrinkage on your pipe? Inside temp constant times coefficient of expansion of PVC equals .... NONE?? So why the NOT TIGHT strut clamps? Sounds like a not very secure installation. Lot of weight to be on the loose.


www.carlon.com/Installation_Training/IT-ISEXPJT.pdf
 
E

emahler

Senior Member
GUNNING said:
I'm confused. If the inspector was asking for expansion fittings then why the stappage question. I found the Carlon guide to expansion fittings. Its really informative. Whats the average extreme temperature differences and it will give you the shrinkage of the pipes. It also does say to loosely strap when using the fittings but I'm a firm believer in a tight pipe install. I hate to see those PVC pipe runs that look like waves on the ocean.

SO whats the shrinkage on your pipe? Inside temp constant times coefficient of expansion of PVC equals .... NONE?? So why the NOT TIGHT strut clamps? Sounds like a not very secure installation. Lot of weight to be on the loose.


www.carlon.com/Installation_Training/IT-ISEXPJT.pdf
Click to expand...

no mention by the inspector of expansion couplings....that just arose as a topic through the course of the thread...but it plays no factor into this particular case...
 
O

ohm

Senior Member
Location
Birmingham, AL
cadpoint said:
Cush-A-Clamp

thats not there only "Cush" Product

ZSI products



http://www.zsi-inc.com/index.php?page=1&s=
  1. Tube Sizes: 1/4" to 6-1/8"​


  2. Pipe Sizes: 1/4" to 6​
This is what the elevator man just left at the job. Hope that helps.
Click to expand...

They look good, datasheet doesn't say if the're listed for PVC. I wonder if you could wrap PVC with a little electrical tape and clamp it with the same unistrut clamp in a pinch?
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
ohm said:
They look good, datasheet doesn't say if the're listed for PVC. I wonder if you could wrap PVC with a little electrical tape and clamp it with the same unistrut clamp in a pinch?
Click to expand...
It is not the non-metallic part that is important. It is the fact that the PCV supports must let the conduit slide.
 
O

ohm

Senior Member
Location
Birmingham, AL
don_resqcapt19 said:
It is not the non-metallic part that is important. It is the fact that the PCV supports must let the conduit slide.
Click to expand...

True the elastomer lets the conduit slide but the metal won't get brittle over time and allow the pvc to fall away. I was thinking a few wraps of tape might be a substitute for the elastomer, in a pinch.
 
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