Getting wire thru long conduit

Reply

  #1  
Old 07-28-14, 09:02 AM
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 5
Getting wire thru long conduit

Hi folks,

What's the best way to push 3 electrical cables through a continuous 1" wide 400ft long flexible PVC conduit?
I'm pretty sure I'm not the first human doing this.

I read about the ShopVac + String method but I have a gut feeling it may not work due to the length of the conduit.

--
Art
 
Sponsored Links
  #2  
Old 07-28-14, 09:08 AM
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 17,113
I have tied a foam ear plug onto the end of a piece of string and used the output (blowing) of a shop vac to blow it through conduit. I've also done with the shop vac providing suction but I've never tired it on anything more than 100' but it worked well over that distance. 400' through 1" conduit is a bit crazy though. Should I ask why such a long, continuous bit of conduit?
 
  #3  
Old 07-28-14, 09:23 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,355
Why 3 cables instead of a feeder to a sub panel?
 
  #4  
Old 07-28-14, 09:24 AM
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 5
It's going to be an underground cable to supply power to a well-head pump about 400ft away from the house.

The current direct-bury underground feed cable kept breaking and we've decided to replace with a a totally new one that has a conduit.
 
  #5  
Old 07-28-14, 09:28 AM
Member
Join Date: Nov 2012
Location: USA
Posts: 664
Get 150 yards dental floss.
Cut a 1" x 11" strip off a tyvek envelope and tie in the center like a bow tie.
Blow through with an air compressor.

Use the floss to pull through some high pound fishing line.
Use the fishing line to pull through the cables.
 
  #6  
Old 07-28-14, 09:28 AM
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 5
3 cables = {red, black, white}
 
  #7  
Old 07-28-14, 09:36 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,355
Those are conductors. Cables are an assembly of conductors in a group or overall sheath.

If your pump is 240 you do not need a neutral. It most likely does require a grounding conductor.
 
  #8  
Old 07-28-14, 10:11 AM
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 5
It's 240V but both the original (UF) and the temporary (current surface cable) have a neutral so I am not going to change this.
 
  #9  
Old 07-28-14, 10:16 AM
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 5
Rigid PVC

I guess the other solution would be to use a rigid PVC conduits which comes in short segments. That will be easier to work with in terms of threading cables in them but there's the issue with PVC cements breaking down over the years and allowing moisture to enter.

Would you guys consider rigid PVC for a long term underground solution?

I will use THWN rated cables as a further protection.
 
  #10  
Old 07-28-14, 10:33 AM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 18,516
It is assumed that any buried conduit will fill with water in time.
 
  #11  
Old 07-28-14, 10:41 AM
Member
Join Date: Nov 2012
Location: USA
Posts: 664
Interesting -
Are you allowed to slope the conduit so that it drains into the basement or well vault??
 
  #12  
Old 07-28-14, 01:13 PM
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 17,113
I don't know why you'd want to allow a pipe (conduit) to transport water into your house. Once the water's inside the pipe the conductors will get wet. Whether or not the water is flowing or standing probably won't make much difference to the life of the wires. I am lucky with my well pump conduit as it stays dry. It's continuous with no seams and both ends are in weather protected locations.
 
  #13  
Old 07-28-14, 02:20 PM
Member
Join Date: Jul 2014
Location: usa
Posts: 279
Use sch 40 pvc.....................use pvc pipe cleaner..........glue

this is a wet location.......NEC 310.8 (C) (2) use THHW,THWN,THWN-2 OR OTHER wire RATED FOR A WET LOCATION

the pipe will have water in it. We do not care.

or the pipe will dry out. we do not care.

the wire will hold up.
 
  #14  
Old 07-28-14, 02:32 PM
Member
Join Date: Nov 2012
Location: USA
Posts: 664
Originally Posted by Pilot Dane
I don't know why you'd want to allow a pipe (conduit) to transport water into your house.
It keeps hard to access wires from rusting out. That's a good thing.
Same way a downspout transports the water to a location where it's easy to deal with.
Yes, you might have an occasional basement drip-drip during wet weather, but that's manageable.

Originally Posted by Pilot Dane
Once the water's inside the pipe the conductors will get wet.
You indicated they all do. They last longer when there is a drain that lets them dry out.

Originally Posted by Pilot Danbe
Whether or not the water is flowing or standing probably won't make much difference to the life of the wires.
Really? Why?

My umbrella gets wet, then dries out. That's what umbrellas are supposed to do.
Conduit rated wires get wet, then dry out, isn't that's what they're supposed to do?
 
  #15  
Old 07-28-14, 02:59 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,355
The conduit system is supposed to be complete end to end before the wiring is installed. You do not slide the conduit over the wires and glue.
 
  #16  
Old 07-28-14, 03:12 PM
Member
Join Date: Jul 2014
Location: usa
Posts: 279
you may pull a string into a conduit as you glue it together.........take a 12 foot wire ............attach your 400 ft string to the end.......push through 2 sections of pipe ....glue the 2 sections together....do this over and over...........

keep the string moving so it will not stick to the glue......

when done...pull a larger rope to pull the wire
 
  #17  
Old 07-28-14, 03:47 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
I would suggest leaving the neutral, too, since you may want to put a heat tape or light at the pump location. 400' is a step. What size wire are you planning on using?
 
  #18  
Old 07-28-14, 03:54 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,460
There really isn't a length limit a string can be pulled thru a conduit. When you pickup your supplies... pick up a 500' coil of fishing/drag line and a mouse the same size as the pipe.

I've pulled a string with a vacuum up to +1500'. A good shop vac will pull a 400' line in a few seconds. After the drag line is pulled..... you'll pull in a rope. Probably 1/2" or 5/8" based on what you are pulling.
 
  #19  
Old 07-28-14, 07:06 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,213
What's the best way to push 3 electrical cables through a continuous 1" wide 400ft long flexible PVC conduit?
Will never happen. You should probably call in a professional for this job.
 
  #20  
Old 07-29-14, 04:00 AM
Member
Join Date: Apr 2007
Location: Near Buffalo, NY
Posts: 4,239
Guys, I bow to your knowledge, but did you see the word flexible in arthury's original post? This raises a flag for me. Seems like Liquid-Tight might pass the birdie and a light string, but it would balk at allowing three large wires to be pulled through 400 feet.
 
  #21  
Old 07-29-14, 04:40 AM
bigboypete's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2013
Posts: 218
Guys, I bow to your knowledge, but did you see the word flexible in arthury's original post? This raises a flag for me. Seems like Liquid-Tight might pass the birdie and a light string, but it would balk at allowing three large wires to be pulled through 400 feet.
400' of liquidtite!???!!!!

That's not going to fly. NEC 356.12

I guess the other solution would be to use a rigid PVC conduits which comes in short segments. That will be easier to work with in terms of threading cables in them but there's the issue with PVC cements breaking down over the years and allowing moisture to enter.
What are you proposing here? Assembling conduit around the wires? That is also a code violation and a very sloppy practice.

Like Joe said.... you need to hire proffesionals.
 
  #22  
Old 07-29-14, 06:01 AM
Member
Join Date: Jul 2014
Location: usa
Posts: 279
400' of liquidtite!???!!!!


you may if you want to.

NEC 356.10 (5)...................i use long carflex all the time.....lay it out straight..pull the wires in......coil it up like a hose........install like a cable.

you can also buy liquidtite with any size wire in it ...any number of wires.... 400 ft long
 
  #23  
Old 07-29-14, 06:12 AM
bigboypete's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2013
Posts: 218
400' of liquidtite!???!!!!


you may if you want to.
That's right, I forgot he is doing direct burial. But I still wouldn't use it, not very practical.

Maybe you would if you have some money burning a hole in your pocket.
 
  #24  
Old 07-29-14, 07:32 AM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,213
What's the best way to push 3 electrical cables through a continuous 1" wide 400ft long flexible PVC conduit?

Will never happen. You should probably call in a professional for this job.
I had assumed that by flexible PVC conduit the OP wanted to use ENT, but it cannot be used outside or direct buried. LFNC (Carflex) would work, but would be very expensive. I believe that for a beginning DIYer that a 400 foot wire pull will be more of a challenge then what he's equipped for. It doesn't take much experience to know that PVC sch 40 is the way to go on this.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'