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Joined: Apr 2001
Posts: 507
G
Member
We are running 3" rigid conduit for a 200HP motor located on top of a grain elevator. The vertical rise is about 180', the conductors will be 500mcm THHN, pull boxes every 50'.

How would you support the conductors in the pull boxes??

In the past I've used kellum grips, but I've seen places where the grips can cut through the conductor insulation and that is a major concern.

I've also used sheet rubber wrapped around the conductors and tied off in the box with a rope or cable.....not materials listed or approved for this application.

I've seen, but not used, a rubber or wooden "bung" drilled to fit tight on the conductors which then wedges tight into the top of the rigid pipe.
Are these still available? who makes them?

When I asked these questions at the wholesale house I just get that glassy eyed look and a shoulder shrug.

What would you do??

thanks
GJ

Joined: Oct 2000
Posts: 4,081
Likes: 3
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GJ,

I've heard others talk of wedge-type supports but I don't have any info on them. I was able to find some interesting info on maximum weights to be supported by cable though. If I find any more info I'll post it here.
http://www.kerite.com/webpages/catalogfiles/continuous_support_power.asp

[Linked Image]
Bill


Bill
Joined: Dec 2000
Posts: 4,291
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I'll get you the wedge info today, as I have the OZ book open on my desk @ the office, but don't think that wood is code compliant. I'll try to post it tonight.

Joined: Apr 2001
Posts: 507
G
Member
electure,

Thanks, I ordered what I needed today.

OZ-Gedney makes two different wedge type conductor supports. One can be installed after the wire is in the pipe. The other screws on the end of the raceway and the condutors are pulled through.

I'm not sure about the material but I'll report back after we get them. They have to be special ordered to fit the conductors.
later,
GJ

Joined: Dec 2000
Posts: 4,291
Member
GJ, The OZ Gedney type "S" Cable support is made of impregnated hardWOOD. What will they think of next??
The type "D",(split, so it can be used in existing installations), and type "R" (that you pull the wires through) are made of phenolic resin. Hope you ordered the former, 'cause the type "R" looks like a real pain in the %!*< to install.


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