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Author Topic: Conduit Wire Pulling  (Read 16330 times)

Jerome Malsack

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Re: Conduit Wire Pulling
« Reply #10 on: January 13, 2014, 08:32:35 pm »

With 2, 3 and 4 inch we might start to see a mini battery truck wireless car with led lights and camera?   to pull the string down the pipe. 

This would presume a 40 percent fill? 
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Jeff Bankston

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Re: Conduit Wire Pulling
« Reply #11 on: January 13, 2014, 09:25:22 pm »

as a commercial electrician i will tell you NEVER pull wire in a conduit with wire in it. i tried a few times when i was a helper. if you have room in the condiut for more wire pull the existing wires out. check the code book or an Uglys pocket reference for condiut fill for the type of wire you are pulling. you might need to use the calculation fill formula. if you dont have room run another pipe. if the existing wires are in great shape you can pull them back in with the new wires at the same time. i'v pulled data wire also and its a pita due to the outer jacket. use soap all the way. pull it easy and make sure the guy feeding it has enough slack so it doesnt drag on the box connector when pulling.
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Stephen Swaffer

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Re: Conduit Wire Pulling
« Reply #12 on: January 13, 2014, 10:27:56 pm »

I'm by no means an expert conduit installer, but here's what I can contribute:
  • Plastic bushings should be used at every conduit fitting that is attached with a locknut inside the box. I don't know the code requirements on bushings, but even if not required they are not prohibited, and I've scraped the insulation on wires pulling them through unbushed fittings. They are inexpensive and a good idea.
  • One big but often overlooked reason for a maximum fill capacity is heat dissipation. That makes me wonder about the wisdom of installing lots of wires in a large conduit -- might be better to have multiple smaller conduits in some situations.

Bushings are required for any wire #4 AWG and larger-even on PVC conduit, but they never hurt.

I doubt heat dissipation is a concern on comm cables-though it could be on speaker runs.  On power wiring, the NEC requires an ampacity derate for the number of current carrying conductors-including neutrals if they are not part of a multiwire branch circuit.  Above 9 conductors this derate is 50% or more-so it takes a much larger conductor to get your ampacity-most guys that pay attention to the derates like they should will size/plan conduit runs to not exceed 9 current carrying conductors-unless there is a really good reason to do so.

The utilities around here require conduit sizes two sizes bigger than NEC and long sweeps-makes their pulls super easy!

If I were pulling a lot of data/comm cable I think I wold look hard at investing in some of the wire mesh pulling grips.   I have not used them a lot-but they seem to work well and keep wire from catching at joints.
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Steve Swaffer

Jay Barracato

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Re: Conduit Wire Pulling
« Reply #13 on: January 14, 2014, 09:03:28 pm »

Bushings are required for any wire #4 AWG and larger-even on PVC conduit, but they never hurt.

I doubt heat dissipation is a concern on comm cables-though it could be on speaker runs.  On power wiring, the NEC requires an ampacity derate for the number of current carrying conductors-including neutrals if they are not part of a multiwire branch circuit.  Above 9 conductors this derate is 50% or more-so it takes a much larger conductor to get your ampacity-most guys that pay attention to the derates like they should will size/plan conduit runs to not exceed 9 current carrying conductors-unless there is a really good reason to do so.

The utilities around here require conduit sizes two sizes bigger than NEC and long sweeps-makes their pulls super easy!

If I were pulling a lot of data/comm cable I think I wold look hard at investing in some of the wire mesh pulling grips.   I have not used them a lot-but they seem to work well and keep wire from catching at joints.

My experience (long ago) was mostly residential including large group homes (think college fraternity house) going from room to room. A big thing was effective communication between the person pulling and the person feeding. I would have loved to have had cell phones back in those days.
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Jay Barracato

Mike Sokol

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Re: Conduit Wire Pulling
« Reply #14 on: January 15, 2014, 08:45:11 am »

A big thing was effective communication between the person pulling and the person feeding. I would have loved to have had cell phones back in those days.

We had walkie-talkies back when I was doing industrial power. But it's great to have cell phones with a blue-tooth ear buds for this kind of work. I did exactly that a few months ago in my own house while pulling wire beneath a crawl space for a new subpanel. My one son fed the wire from the basement, my other son pulled the wire up in the sub-panel, and I was in the crawl space below keeping everything straight and untangled. I just did a conference call between the three of us and put a bluetooth earbud in my own ear, while they put their cells on speakerphone. It worked great. 
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Mike Sokol
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Stephen Swaffer

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Re: Conduit Wire Pulling
« Reply #15 on: January 15, 2014, 11:41:54 am »

How did dad wind up in the crawl space??
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Steve Swaffer

Jamin Lynch

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Re: Conduit Wire Pulling
« Reply #16 on: January 15, 2014, 12:24:58 pm »

We had walkie-talkies back when I was doing industrial power. But it's great to have cell phones with a blue-tooth ear buds for this kind of work. I did exactly that a few months ago in my own house while pulling wire beneath a crawl space for a new subpanel. My one son fed the wire from the basement, my other son pulled the wire up in the sub-panel, and I was in the crawl space below keeping everything straight and untangled. I just did a conference call between the three of us and put a bluetooth earbud in my own ear, while they put their cells on speakerphone. It worked great.

I was "helping" the electrician install the main feed wire from the meter bank at the end of the building to my store load center, we didn't know how long it was, so rather than guess on wire than cost a few dollars a foot we made a kite out of a plastic bag, attached it to a pull string and used a shop vac to send it through the conduit. We then marked the ends pulled the string back out and measured the length.

We were able to talk to each other by speaking into the pipe while pulling the wire. Strictly low tech.
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Josh Millward

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Re: Conduit Wire Pulling
« Reply #17 on: January 15, 2014, 12:39:41 pm »

We were able to talk to each other by speaking into the pipe while pulling the wire. Strictly low tech.
Yeah, it is surprising how well that works!
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Josh Millward
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Mike Sokol

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Re: Conduit Wire Pulling
« Reply #18 on: January 15, 2014, 03:15:44 pm »

How did dad wind up in the crawl space??

Hmmmm.... Maybe I should rethink that next time. Seriously, getting teenagers to help in any capacity is a victory. The good thing is that I'm teaching them all about electrical safety as we go along and they know way more about CPR and shock dangers than most master electricians. They're also my standby emergency crew when I have to work inside a live box (which I refuse to do while I'm alone). They standby with a cell phone and know the 911 drill and compression CPR in case something goes terribly wrong. Even though I've done this for 40+ years I'm not stupid enough to think that I can't get shocked and knocked out or worse.
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Chris Clark

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Re: Conduit Wire Pulling
« Reply #19 on: January 18, 2014, 04:09:34 am »

To get the pull string though the conduit initially we used something that looked like a little rocket with a spool of thread on the back. <snip>
Greenlee makes a setup like this. We have one of these where I work, I had never used it until last year, it can be a bit cumbersome to set up, but works amazingly well! (I call it a mouser, the connotation being that the "rockets" are like mice in a sense... don't know what the real name is).

Needed to fish pull line through a ~350ft 2" conduit underground... that had been left exposed to the elements by the installing contractor before we were able to pull it, in the middle of March. Needless to say there was some ice in it. We put the mouse in, with the pull line attached, powered up the blower (sounds like a small jet engine!) and within about 5 seconds watched a geyser of water and ice blow 3-4 feet in the air at the other end of the conduit, along with the mouse. That is one powerful little bugger! If you do a lot of conduit runs I suggest it as a wonderful investment, the one we have has "mice" and end fittings for conduit from 1/2" all the way to 4".
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