Underground conduit

[logan92@att.net]

I was wondering if I ran conduit in a straight trench how long does the run have to be before i need a pull box? I searched the 2011 NEC and couldn't find an article showing me the code

 

[ActionDave]

As long as you need it or as long as you can make it. If you were to go around the earth in a straight line you would not exceed three hundred sixty degrees which is the only restriction the NEC has when it comes to pull points.

 

[PetrosA]

... If you were to go around the earth in a straight line you would not exceed three hundred sixty degrees which is the only restriction the NEC has when it comes to pull points.

I'll bet that would need one heck of a vac to pull the string through, though.

 

[ActionDave]

Well if you can make around the earth then getting one end of the conduit up past the atmosphere is not so much more work.

 

[Fulthrotl]

Well if you can make around the earth then getting one end of the conduit up past the atmosphere is not so much more work.

if you go to the vacuum of space, you will have to put a seal off,
to keep the earths atmosphere from leaking out to space. so,
after you pull it, who's gonna go up into space to pour the
seal off?

then, there are expansion joints. they aren't air tight, either.

now, about the conduit supports.....

 

[BAHTAH]

Maximum Pulling Tension

Maximum Pulling Tension

I was wondering if I ran conduit in a straight trench how long does the run have to be before i need a pull box? I searched the 2011 NEC and couldn't find an article showing me the code

Wire manufactures publish data associated with the maximum pulling tension on conductors. The lenght of conduit will be effected by the conductor size and if you are installing a combination of conductor sizes in the same conduit. Here a link to Southwire, they have an installation guide you can get on-line that may be of help.
http://www.southwire.com/TechnicalSupport.htm

 

[ptonsparky]

I was wondering if I ran conduit in a straight trench how long does the run have to be before i need a pull box? I searched the 2011 NEC and couldn't find an article showing me the code

We have pulled 1300 feet. We could pull further with no box.

 

[babaregi]

Physics

Physics

if you go to the vacuum of space, you will have to put a seal off,
to keep the earths atmosphere from leaking out to space. so,
after you pull it, who's gonna go up into space to pour the
seal off?

then, there are expansion joints. they aren't air tight, either.

now, about the conduit supports.....

As a mind experiment...nothing would leak or be vacuumed out into space. The atmosphere stays in place with or without the pipeline into space due to the Earths gravity.