Conduit run

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joebell said:
Carl,

The LB is not consisdered as 90 degrees it is considered to be a "pull point". I personally do not like to use them in bigger pipe and wire applications. I would rather use a deep can or trough. I find it hard to pull the larger size conductors through and have them pulled correctly to get the cover on the LB.
Joe
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Joe I kinda thought that myself about the LB's. My supervisor thinks that using several LB's are the best way to make this pull but I would think using 90's at key bend areas would be alot easier to pull through than to pull the 4 #300's out at a corner and than pushing them back in towards the next corner area. Of course my supervisor calls LL's,LR's,& LB's all LB's.
I've told him the differences but he still won't call them by the right name.
 
Carl

The owner of the company I work for calls them (L)abor (B)urdens. Let me guess your supervisor sits behind a desk and directs?

He may have a different opinion if he helped pull this in. Did you say XHHW?

Joe
 
Carl,
Wouldn't the gradual 90 degree of an elbow cause less friction and therefore be much easier
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The pulling calculations show no differnece in the pull force required between a standard conduit 90 and a long radius, however there is a big reduction in the sidewall pressure (crushing force between wire and inside radius of the raceway), and the sidewall pressure, not the pulling tension, is often the limiting factor when doing a pulling calculation.
Don
 
Carl,
My supervisor thinks that using several LB's are the best way to make this pull but I would think using 90's at key bend areas would be alot easier to pull through than to pull the 4 #300's out at a corner and than pushing them back in towards the next corner area.
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If you are using an LB for this pull make sure that you look at 314.28(A)(2)&(3). A standard 3" LB will probably not be suitable.
Don
 
joebell said:
Carl

The owner of the company I work for calls them (L)abor (B)urdens. Let me guess your supervisor sits behind a desk and directs?

He may have a different opinion if he helped pull this in. Did you say XHHW?

Joe
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Why yes Joe , he does sit behind a desk about 75% of his day.
The question of XHHW is also yes the area will be wet most of the time and so as a precautionary measure I feel it would be the best wire choice for moisture resistance due to condensation possibilities within the conduit. I know this will make it a bit more difficult to pull but I'd rather be assured as to the safety factor involved.
Carl
 
Krim said:
Why yes Joe , he does sit behind a desk about 75% of his day.
The question of XHHW is also yes the area will be wet most of the time and so as a precautionary measure I feel it would be the best wire choice for moisture resistance due to condensation possibilities within the conduit. I know this will make it a bit more difficult to pull but I'd rather be assured as to the safety factor involved.
Carl
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why not thwn?
 
I've heard mention of using baby powder on XHHW from guys using it on smaller motor leads(#12). Don't know about 300kcmil though? I've tried it on short runs of SO cord sleeved in conduit and it seemed to help.
 
Cow said:
I've heard mention of using baby powder on XHHW from guys using it on smaller motor leads(#12). Don't know about 300kcmil though? I've tried it on short runs of SO cord sleeved in conduit and it seemed to help.
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I think that powdered soapstone was an old-school pulling lube. Not sure if anyone still uses it or not. About the same as talc.
 
The pulling calculation from Polywater shows a lower coefficient of friction for XHHW than for THWN. I made ~2000' pull in 2" with 2 pulling points , one splice box and seven 1/0 XHHWs without any problem this summer. This was an existing run with the load being increased. I did have to change out all of the 90s to ones with a 3' radius to get the side wall pressure low enough.
Don
 
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