Pulling Cable in PVC - Burning Through Elbows (Data)
Pulling Cable in PVC - Burning Through Elbows (Data)
(OP)
I'm looking for some data on determining when pulling rope burns though PVC conduit elbows in order to determine when to use rigid metal conduit elbows. My electric coop currently requires the use of rigid metal elbows for pulls over 250 feet. I would like to see data to support this. It's my opinion that it should be based on the sidewall bearing pressure, speed of pull, and the type of pulling tape (steel should generate less friction than nylon). Does anyone have any data or experience concerning this matter? My efforts to find specific data on this have been unproductive (Southwire, Carlon, IEEE, AEIC, etc.).
FYI: We pull 25kV urd XLP jacketed cable into 3" PVC, one cable per conduit.
Thank you in advance.
FYI: We pull 25kV urd XLP jacketed cable into 3" PVC, one cable per conduit.
Thank you in advance.






RE: Pulling Cable in PVC - Burning Through Elbows (Data)
Have you tryed using a wire pulling lubricant?
RE: Pulling Cable in PVC - Burning Through Elbows (Data)
RE: Pulling Cable in PVC - Burning Through Elbows (Data)
The requirement of steel elbows is seen frequently, but I'm not aware of any published data to support the practice.
RE: Pulling Cable in PVC - Burning Through Elbows (Data)
RE: Pulling Cable in PVC - Burning Through Elbows (Data)
Related discussion at Thread238-61500
RE: Pulling Cable in PVC - Burning Through Elbows (Data)
Busbar, I read Thread238-61500 before I started this one, but I was looking more specifically for experimental data to support the use of rigid metal elbows. Thanks anyway.
I think this matter is in dire need of some specific experimental studies.
RE: Pulling Cable in PVC - Burning Through Elbows (Data)
I would be concerned about using metal elbows or conduit if you are only putting one phase in each conduit. I would also be concerned about bare steel if there is a copper ground grid.
RE: Pulling Cable in PVC - Burning Through Elbows (Data)
EPRI has done extensive experiments on this and it is published in the document EL-3333-CCMV2. The cost of the document is around $2,500, which is quite pricey.
AEIC document CG5-90 ($25.00) is what I purchased and it was exactly what I was looking for. It has all the info you'll need for a succesful pull.
RE: Pulling Cable in PVC - Burning Through Elbows (Data)
So when does pulling rope burn through PVC elbows? Or do we have to pay the 25 buck also to find out?
RE: Pulling Cable in PVC - Burning Through Elbows (Data)
"A coarsely braided fiber pulling line or stranded steel rope will wear through duct much more rapidly than a nylon jacketed pulling line."
"Typical cable pulling speeds for power cables range btwn 10 and 50 ft per minute."......"High pulling speeds also result in an increased rate of frictional heating in bends and can result in additional wear in PVC."
My conculsion is to try using steel tape(not stranded) without steel elbows and being sure to pull at proper speeds with a tension gauge attached. We will run cable pulling calculations prior and will be conservative.
Also concerning surging, AEIC states "Cable pulls with pulling lines that have a large amount of elasticity (nylon)surge more readily than pulls with lines that have little elasticity." (steel tape)
The document has a lot of other useful data on coefficient of friction, SWBP, tension calcs, etc.
Hope that helps.
RE: Pulling Cable in PVC - Burning Through Elbows (Data)