pull boxes

[stevegw]

I have a 1000' run of pvc conduit to run, I thought it used to be required to have a pull box every 300'. I cannot find anything now, am I overlooking a section or was it never there?

 

[480sparky]

Never has been an NEC requirement.

 

[stevegw]

Thanks I think it was a local rule they had.

 

[cowboyjwc]

This one still comes up from time to time. Just another one of those urban myth codes.

 

[infinity]

The NEC wouldn't require a pulling point in this run unless it had the equivalent of more than 360 degrees of bend. Having said that, you'll still need to be able to get the wire in the pipe.

 

[raider1]

I also like to point out that many engineering specifications have a maximum run length for a conduit before a pullbox is required.

I have seem many specs that required a pullbox ever 100' for above ground installations and 300' for underground installations.

Chris

 

[LarryFine]

I have a 1000' run of pvc conduit to run, I thought it used to be required to have a pull box every 300'.

Nope. The rule that never existed was for one every 100'.

 

[480sparky]

........you'll still need to be able to get the wire in the pipe.

As well as get conductors that long.

 

[K8MHZ]

If you are good at catch and release, here is the formula:

Length in feet of fish tape 1 plus length in feet of fish tape two minus 3 = length in feet between pull points.

I always use the above because the vacuum and mousey trick does not work in every instance, especially in EMT runs.

 

[shamsdebout]

What would you guys recommend or are there too many varibles to give a generalized distance?

 

[LarryFine]

If you are good at catch and release, here is the formula:

Length in feet of fish tape 1 plus length in feet of fish tape two minus 3 = length in feet between pull points.

'Splain, please?

It sounds like you're suggesting pushing the wire half way with one fishtape, catching the end with a second fishtape, unhooking the first one, and pulling it the rest of the way with the second.

 

[480sparky]

'Splain, please?

He's sending a fish tape in from both ends and trying to 'catch' them together, then use one end to pull out both fish tapes with the wires attached to the 'released' tape.

 

[NewOnMyOwn]

Yup, he's basically saying you can go the distance of your two longest snakes.

Put a hook on the end of one and make a knot with many loops on the other and catch them in the middle.

 

[LarryFine]

He's sending a fish tape in from both ends and trying to 'catch' them together, then use one end to pull out both fish tapes with the wires attached to the 'released' tape.

I wouldn't trust the tapes hooked together for such a long run, because of the drag. I've seen fishtape hooks bend open, and that's when we were able to hook and tape the wires by hand.

 

[bob]

What would you guys recommend or are there too many varibles to give a generalized distance?

Depends on the cable size, number of cables, number of bends, length of straight runs, lubricant, etc to calculate the loading on the cable.
If you have 4 #14's you may not need any, but if you have 4 # 1000's you may. You have to make the calculation to know for sure. Give some information.

 

[480sparky]

I wouldn't trust the tapes hooked together for such a long run, because of the drag. I've seen fishtape hooks bend open, and that's when we were able to hook and tape the wires by hand.

I might consider that if it's, say, two nice wide 90s (no factory 90s), 1" pipe and just 3-4 10s or 12s.

But otherwise, I only do that as a last resort. I'd rather try vac'ing a mouse, or using compressed air to get a jetline in, then pull a rope back through to do the actual pull.

 

[NewOnMyOwn]

I wouldn't trust the tapes hooked together for such a long run, because of the drag. I've seen fishtape hooks bend open, and that's when we were able to hook and tape the wires by hand.

I've only done it or see it done to pull a poly drag line in the pipe, then use the drag to either pull the wire (if small enough) or pull in a bigger rope.

 

[infinity]

For really long runs you can use one of these. They come in lengths up to 1200'.

http://www.gmptools.com/nf/89202.htm

 

[masterinbama]

I always put the string in as I go on larger pipes.

 

[infinity]

I always put the string in as I go on larger pipes.

That works too. We've done that when running concrete pipe. Take some nylon jet line and tie a bunch of loops on the end. After you install 50' or so shove in a 1/4" snake with a hook on the end and pull the ball right to the mouth of the last pipe. Leave it there until you get to next 50' installed and repeat that process.