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Joined: Mar 2005
Posts: 48
R
Member
Question: Can 2-#12,1-#12Gnd XHHW-2 stranded copper conductors be safely pulled through a 1-1/2" directly buried PVC coated GRS conduit that is 500 feet long with 335 degrees of 24-inch sweeps?

How do the experts do this??

Joined: May 2002
Posts: 1,716
R
Member
Piece of cake, the bigger question is what is the load and voltage drop?

We would either blow or vacuum a string in the conduit and then pull a 1/4" or 1/2" rope in to it for the actual pull, wire lube would be a good idea too.

Roger

Joined: Jul 2004
Posts: 9,673
Likes: 7
G
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Since a spool of wire is typically 500' long it will be real important to know if this is 495 feet or 505. ;-)
Be sure you start with a virgin spool.


Greg Fretwell
Joined: Jan 2004
Posts: 615
J
Member
I have found this http://www.electrician2.com/electa1/ductwirepull.html link handy before.

Joined: Oct 2002
Posts: 482
Z
Member
An interesting link, but the first "rule" bullet-point conflicts with others. To say that the radius of a bend does not affect pulling tension goes against everything I have learned in over a decade of pulls. Maybe I'm imagining it? I think not.

Joined: Nov 2005
Posts: 7
T
Junior Member
That 1-1/2" sounds nice, my employer would of probably used 3/4" pvc.

Joined: Jan 2003
Posts: 4,391
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Quote
To say that the radius of a bend does not affect pulling tension goes against everything

I think that once your into large pulls with high pulling tensions (a few thousand pounds) the difference in pulling tension threw a standard 90 and large 90 is not going to be meaningfull.

The large radius 90s are used to distribute the side wall pressure over a larger area to prevent insulation damage.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
I think the folks at the link meant to say "assumptions," rather than "observations." Looking at the other items in the list, this seems to be the case.

In reality, radiun DOES matter. Otherwise, we'd all be pulling through LB's. Farther down the list, they do reference the need for sweeps.

Likewise, our own experience is somewhat different on the other points. We run oversize pipe when we can. We've all seen the limits of adding a pull string for future use.
Most notably absent is any reference to the friction of different wire insulation types.

Let's not overlook the difference between 'pulling tension' and 'sidewall pressure.' Since rather small wires are involved, the use of steel sweeps for the turns is indicated in a PVC run. While the poster is running steel pipe, that is not always the case.

(Too bad the original poster didn't use 2" rather than 1 1/2". Had he done so, he could have used his pet ferret to pull those three little wires for him!)

[This message has been edited by renosteinke (edited 12-19-2006).]

Joined: Oct 2002
Posts: 482
Z
Member
I like the ferret idea! I wonder if Greenlee has them in their catalog?


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