pulling cable in conduit

davidj · November 13, 2012, 11:20:23 AM

Any hints for pulling cable through conduit? I've got to pull four 6awg stranded cables through about 80' of 1 1/4" conduit (including 2 90s). Should I do them all at once or as two or 4 separate pulls? Is the bag+shop vac approach for getting the pull string through pretty fail safe or should I invest in a 100' fish tape? I've also got cable lube - anything else I need up there to make this work? If I don't get this sorted out over the weekend I might have 3' of snow on the ground next time I'm up there which will make the whole thing much more complicated.

Thanks for any help...

Redoverfarm · November 13, 2012, 11:41:03 AM

The 90 's will give you problems unless they are sweeping 90's. That is really tight in 1-1/2" conduit. I would have probably used at least 2" but if it is already bought then you will have to work with what you got. Is the conduit already glued together? If not I would make seperate pull meaning straight to el's then straight to el's while they are seperated. Then once you get the cable all the way through then glue it up into a continuious piece. When you set up your wire do not bunch all the ends at one spot. Stagger the ends so that you do not have a blunt end at the front. Tapered will work better. I always tapper and tape to make it as gradual as possible. And lubricate well. Good luck.

November 13, 2012, 03:22:16 PM

I couldn't find long sweep 90s in 1-1/4" so they are regular 90s.

Redoverfarm · November 13, 2012, 03:31:49 PM

Quote from: davidj on November 13, 2012, 03:22:16 PM
I couldn't find long sweep 90s in 1-1/4" so they are regular 90s.

Ouch!!! I got mine at HD or Lowes. Seemed they had a decent supply. Are you using electrical conduit or regular PVC conduit?

MountainDon · November 13, 2012, 06:09:26 PM

If it is not already glued together, or even if it is, I'd highly recommend getting the long el's and inserting them. Those short 90 degree bends are bad with 14 gauge wire.

http://www.lowes.com/pd_51244-223-UA9AGBL_4294722504__?productId=3129161&Ntt=elecytrical+conduit

November 13, 2012, 06:31:16 PM

Don he may be using just white PVC pipe with regular 90's. I have never seen a straight 90 in electrical conduit just because you can't pull wire through them assembled. Normally a connecting box (inside or outside 90's) are used for sharp turns but they are intended for above ground use.

MountainDon · November 13, 2012, 07:30:09 PM

Well, the good thing is that if he has been using the white PVC it can be cemented to this stuff with regular PVC cement.

I've used the 90's with the removable plate, above ground. I don't think I'd ever noticed if there were short 90's in grey as I'd never want to struggle that much.

yankeeredneck · November 13, 2012, 07:34:37 PM

That will be a tight bends but it can be done. I have pulled miles of wire through conduit-----low and high voltage and the best way I have been able to do it if the conduit is already together is the vac method or fish-tape. With the vac method, you want to make sure that you secure the wire onto the pull string very, very good. You don't want to be 3/4 of the way and the wire comes undone. With the fish-tape way, same thing. Although it is messy, the lube helps a lot and it will also with the bends. Staggering the wires about every 4-6 inches has always worked for me.

Personally, I favor the fish-tape as you can twist, re-bend, or what have you to help pull wire. Plus you can always use it some where down the road. It is one of those tools that when you need it, you're glad you have it.

ChuckinVa · November 13, 2012, 10:00:32 PM

I would glue the pipe together first. Then buy a 100 foot fishtape and push it through your conduit. 2 90's are not bad. I believe you are allowed 4 with out a pull box. As Redover indicated, make the wires as tapered as possible by stripping the insulation back at different lengths and then attaching to the fishtape and then taping the tapered wire back to the last piece of insulation. use lots or wire lube if the conductor requires it. There are manufacturers that are producing wire with insulation that does not require wire lube. Southwire is one and their trade name is Simpull.If you have help it is a lot easier for one to pull while the other pushes the conductor and keeps it lubed. If you are using grey electrical PVC then the sweep ells should be fine. If you are using white PVC plumbing pipe the ells are going to give you problems but depending where they are in the pipe run you might be ok. An 80 foot run should not be bad. Just make sure your conduit is clear of obstructions like rocks or pebbles or dirt before making the pull.
Chuck

November 14, 2012, 01:49:22 AM

Thanks for all of the info.

It's proper grey electrical conduit. Everything's already glued and underground as we needed to backfill before the snow hits so I can't do it in two shorter pulls. The 90s are like the ones in Don's picture, about 6" radius (cf the 18" or 24" radius that I found in larger sizes but that didn't seem to exist for 1-1/4" in my local stores).

I guess I'll buy the fish tape - it's only I bought a cheap 30' tape for the house then a nice fiberglass 50' tape for the cabin, now I need a 100'! The projects keep getting bigger...

Redoverfarm · November 14, 2012, 06:39:31 AM

Quote from: davidj on November 14, 2012, 01:49:22 AM
Thanks for all of the info.

It's proper grey electrical conduit. Everything's already glued and underground as we needed to backfill before the snow hits so I can't do it in two shorter pulls. The 90s are like the ones in Don's picture, about 6" radius (cf the 18" or 24" radius that I found in larger sizes but that didn't seem to exist for 1-1/4" in my local stores).

I guess I'll buy the fish tape - it's only I bought a cheap 30' tape for the house then a nice fiberglass 50' tape for the cabin, now I need a 100'! The projects keep getting bigger...

With the sweeping El's you should not have a problem. A shop vaccume should pull a lightweight line. I use Seine twine # 18 X 225' Mason line which you can pick up at Lowes. If you can pull the line before inserting it and mark the distance on the string it will take the guess work out of determining if it made it to the other end. I just tie a cloth on the end leaving a 8-10" tail and insert it into the conduit. Seal the end around the hose with tape and turn it on. Once the light weight is pulled to the vaccume you can then tie a heavier rope onto it and pull it by hand to use to pull your wire. Attach to the cable and pull it through. Don't put the lube in the conduit until you at least get the light string sucked through. If it hangs before making it to the other end just pull back the other directrion and let go and eventually it will make it. You might have to use your hand to seal around the open end where the string feeds from to make the vaccume pull better. If you can attach an extra length of pull rope with the cables it will be in the conduit if a need arises to pull additional wire (or a bad wire replacement) at a later date. Let us know how it turns out.

NM_Shooter · November 14, 2012, 05:17:44 PM

If you can't make the tight turn at the corners, cut them out and replace them with a pull corner. It will give you intermediate places to catch your breath as you make the next run.

Redoverfarm · November 14, 2012, 05:48:37 PM

Quote from: NM_Shooter on November 14, 2012, 05:17:44 PM
If you can't make the tight turn at the corners, cut them out and replace them with a pull corner. It will give you intermediate places to catch your breath as you make the next run.

I mentioned that Frank but if they are below grade those do not work so well. Yes they are gasketed and suppose

to be waterproof but even above grade on the exterior they are not always.

davidj · November 18, 2012, 01:38:54 PM

We did the wire pull on Friday and it went really well.

I decided to try the shopvac-and-string approach as it seemed more fun and it was really easy. Bought a spool of pull string and tied a bit of plastic bag on to it put, put the shop vac on suck on the other end and just put it on the conduit. It was through in about 2 seconds - so quick I thought it had got stuck on the first bend!

Then I used that pull string (rated two hundred and something pounds) to pull the four 6awg stranded cables. Tied and taped them all together, stripping and bending over the first one to get a rounded "point". A bit of lube in the mouth of the conduit and it went through really easily with Lisa pulling and me feeding/pushing. I was worried about the 200lb string strength but we could have probably done it with 30lb fishing line it was so easily! I couldn't even notice the increase in force as we went around the bends.

The only difficulty was trying to feed the cables. I had a scaffolding pole on saw horses and they kept falling over if I didn't feed it off just right. Next time I'm gonna use something heavier to rest it on and clamp it together.

Here's a picture from the "push" end...

Thanks again for everyone's help.

P.S. I definitely think we picked the right conduit size - based on fill and wire size it only needed 1" but we went 1-1/4". It was so straightforward that any bigger was a waste but smaller would have definitely been harder, if only because of the smaller inline "C" conduit body at the far end and tighter radius bends.
P.P.S. The 1" conduit to the left in the picture also goes to the shed but is currently empty - it's for low voltage (Ethernet? Another solar controller?) but I haven't worked out what to do with it yet.

November 18, 2012, 02:22:37 PM

Glad it worked out for you. The only reason I suggested leaving a heavy pull line in for future use is that it would be harder to pull other wire through if half the conduit already has wire in it.

I have even see an air compressor used to blow a parachute shape rag on the pull line. But you would need more air than a regular construction compressor would supply.

davidj · November 18, 2012, 06:22:15 PM

Whoops, yes, I forgot to leave any pull line in there at all!

BTW, I didn't realize until last week that conduit couplings have a direction (or at least the ones I bought did). The little ridge in the center has a slight slope on it that favors pulling things through from one direction. I'm sure that's one of the reasons my other conduit pulls have been harder as, until now, I've just installed them in a random direction.

flyingvan · November 22, 2012, 11:17:56 PM

This thread was very timely...The shop vac wand fit perfectly over my 3/4" pipe I had to trench in for the phone landline. 120' of pipe with three 90 degree elbows, the vacuum pulled the survey string right through. I just guessed when to stop feeding it and ended up with 50' or so in the shop vac. Thanks for the tip!