bending PVC conduit

Reply

  #1  
Old 10-28-07, 02:39 PM
Member
Thread Starter
Join Date: Sep 2007
Posts: 35
Received 0 Votes on 0 Posts
bending PVC conduit

While installing 1 1/2" PVC conduit to my main panel, I discovered I am 9" off-center between my top plate of the wall and the top of the panel. This distance between the plate and the panel is about 3'. The area is between 2X4 stud walls. It occurred to me that it might be possible to heat the conduit and coax a gentle S-bend in it. Is that possible or is there some flexible conduit that can be used? If heating is possible, what special tools are needed and can they be rented? The error occurred because I mistakenly thought a knockout on top of the main panel lined up with my conduit. Now I realize the knockout only serves the meter side of the panel. The conduit already has four 6ga THHN conductors inside of it. Moving the conduit is possible but it is my last resort. Would it possible and legal to install a juction box at the end of my existing conduit and then use 6/3 Romex for the rest of the distance to the main?
Thanks in advance for your help.
 
Sponsored Links
  #2  
Old 10-28-07, 02:55 PM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,346
Received 50 Votes on 47 Posts
Not sure about whether you can bend the pvc (leaning toward no), but there is flexible conduit available.
 
  #3  
Old 10-28-07, 03:46 PM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Received 0 Votes on 0 Posts
How is it that you conduit already has cable in it? You can't put the cable in until the conduit is completely installed.

Flexible conduit is available. Or you can use a junction box and switch to NM type cable. But again, the wires should NOT already be installed.
 
  #4  
Old 10-28-07, 04:37 PM
Member
Join Date: Sep 2002
Location: welland ontario
Posts: 6,811
Received 87 Votes on 80 Posts
Bending PVC is possible. Use heater or very carefully heat with a torch.

$1000 on ebay

http://cgi.ebay.com/New-Current-Tool...QQcmdZViewItem
 
  #5  
Old 10-28-07, 04:57 PM
Member
Join Date: Oct 2005
Location: USA
Posts: 1,369
Received 11 Votes on 11 Posts
Originally Posted by upflying View Post
Now I realize the knockout only serves the meter side of the panel. .
I'm not sure what this means. The panel is compartmentalized?

If this is the case, consider drilling a new hole. You don't have to use the provided knockouts. The "real" tool is a hydralic punch, but a metal hole saw can work.
 
  #6  
Old 10-28-07, 05:06 PM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
Received 0 Votes on 0 Posts
Use a heat gun, available at any Ace Hardware for about $20. Be VERY careful not to burn the conduit. Go very slow and keep the gun moving. You can do it with the conduit right in place.

I have an $80 Makita gun and the $20 Ace actually gun works better. Plus you can use it for many other projects as well.
I have the smaller "hot box" from Current Tools and it is the ONLY way to bend more than one or two pieces of conduit, but you can't use it for conduit already installed.
 
  #7  
Old 10-28-07, 10:08 PM
Member
Thread Starter
Join Date: Sep 2007
Posts: 35
Received 0 Votes on 0 Posts
Originally Posted by racraft View Post
How is it that you conduit already has cable in it? You can't put the cable in until the conduit is completely installed.

Flexible conduit is available. Or you can use a junction box and switch to NM type cable. But again, the wires should NOT already be installed.
All the conduit is installed except the last three feet above the main panel. I have about 10' of wire hanging out of the end. I'll feed that through the short remaining section of conduit after I change the main panel.
 
  #8  
Old 10-28-07, 10:13 PM
Member
Thread Starter
Join Date: Sep 2007
Posts: 35
Received 0 Votes on 0 Posts
Originally Posted by telecom guy View Post
I'm not sure what this means. The panel is compartmentalized?

If this is the case, consider drilling a new hole. You don't have to use the provided knockouts. The "real" tool is a hydralic punch, but a metal hole saw can work.
The main panel has two vertical 24" compartments. One side containes the meter socket and a top or bottom entrance for service from your utility company. You are not allowed to enter this compartment unless your utility company is present. The other compartment contains a 125 amp main breaker and 12 spaces for breakers. My conduit is in line with a knockout above the meter socket. I thought I could enter the utility side of the panel but that is a no go.
 
  #9  
Old 10-28-07, 10:16 PM
Member
Thread Starter
Join Date: Sep 2007
Posts: 35
Received 0 Votes on 0 Posts
Originally Posted by mitch17 View Post
Not sure about whether you can bend the pvc (leaning toward no), but there is flexible conduit available.
I'll try heating it with a heat gun but I'm afraid I might pinch it. Good thing PVC is cheap if I mess it up. Do you have a link to flexible conduit? I like that idea but is flex conduit NEC legal?
 
  #10  
Old 10-28-07, 10:46 PM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,346
Received 50 Votes on 47 Posts
Originally Posted by upflying View Post
Is flex conduit NEC legal?
Yep.




(Filler for minimum character count)
 
  #11  
Old 10-29-07, 07:58 AM
Member
Join Date: Jun 2006
Location: usa
Posts: 274
Received 0 Votes on 0 Posts
Originally Posted by Speedy Petey View Post
Use a heat gun, available at any Ace Hardware for about $20. Be VERY careful not to burn the conduit. Go very slow and keep the gun moving. You can do it with the conduit right in place.
Good advice.
I use a heat gun to bend PVC conduit all the time.

As stated, I go slow and heat a large section .
I make sure that the entire section where I want the bend (about 2 feet for 1 1/2") is completely soft (I feel of it with my hand), before bending it.

I wear gloves and have a spray bottle of water handy.
When I get the bend that I want, I spray it with water to cool it quickly.
Otherwise, I have to hold it in position while it cools.

Hope this helps
steve
 
  #12  
Old 10-29-07, 09:24 AM
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,944
Received 42 Votes on 40 Posts
I would use a piece of ENT (electrical nonmetallic tube). It is a somewhat flexible "corrugated" PVC conduit that can be glued directly into rigid PVC fittings. It's usually available in bright blue, thus the moniker "smurf tube".

Also, you shouldn't glue or heat the conduit with wires inside; either will damage the conductor insulation.
 
  #13  
Old 10-29-07, 03:19 PM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
Received 0 Votes on 0 Posts
Originally Posted by ibpooks View Post
Also, you shouldn't **** ** heat the conduit with wires inside; either will damage the conductor insulation.
Not so at all. This is done all the time in the trade with NO ill effects.
 
  #14  
Old 10-29-07, 05:57 PM
Member
Join Date: Jan 2004
Location: Oregon
Posts: 1,219
Received 0 Votes on 0 Posts
Conduit systems are supposed to be complete between pull points end to end prior to installing conductors. This is a code requirement.

One of the reasons given on this board (not mentioned in the code, just a well believed theory) is that the PVC conduit glue is a solvent glue that works by solvent welding the conduit. Conductor insulation can be softened and damaged by this solvent; THHN conductor, for example, is PVC with a nylon cover.

Speedy, you are in the trade and I am not, but could you confirm that professionals will actually heat bend PVC conduit, with conductors inside the conduit. My gut response is that this is a tremendously bad idea, given that you have to heat the _PVC_ conduit up to its softening point, and the conductors inside the conduit are made out of similar material.

Even if this sort of heat bending of conduit with conductors is trade practise, I would strongly advise against using this as a DIY technique, with someone who has _never_ bent PVC conduit before, and without a proper temperature controlled bending heater.

-Jon
 
  #15  
Old 10-29-07, 07:02 PM
Member
Join Date: Oct 2007
Location: Delray Beach, FL
Posts: 406
Received 0 Votes on 0 Posts
If you want to keep it it in hard pipe, buy 2 - 45 degree elbows and some couplings.
Put one 45 on the end of your existing pipe turned towards the center of the panel, then use the other one with a short piece in between the two to turn down into your panel.
Make your own offset.
Or get a female adapter, 2 straight flex connectors, and a piece of nonmetallic flex.
Don't use metal flex as then you get into grounding issues and will need to install a bond bushing.
 
  #16  
Old 10-29-07, 07:19 PM
Member
Join Date: Apr 2006
Location: New Bern, NC
Posts: 1,623
Received 0 Votes on 0 Posts
Racraft seems to be the only one to mention, (sorry if i missed you)

A conduit run is supposed to be complete before you add the conductors.

this is so that doing things like heating the conduit, or glue, will not adversely affect the wires.

I say you tear all the wires out of the conduit, buy new and do it right.

next time, do your research before you do your work.
 
  #17  
Old 10-29-07, 09:46 PM
Member
Join Date: Oct 2007
Location: Delray Beach, FL
Posts: 406
Received 0 Votes on 0 Posts
Yes, the conduit run should be complete before installing conductors but what is done is done.
A couple of drops of glue are not going to melt the insulation off the wire so don't get too wound up.
Can you pull the wire back a couple of feet before you install the balance of the conduit?
Trying to slide conduit on and then get it into a fixed panel can be quite difficult especially when coming into a hub on the top of a panel.
Are you using a hub of some sort to prevent the entry of water into the panel?
 
  #18  
Old 10-30-07, 08:08 AM
Member
Join Date: Jun 2006
Location: usa
Posts: 274
Received 0 Votes on 0 Posts
Just to clarify my first post...

I missed the OP saying that the wire was already in the conduit.

So....you're not supposed to heat (or glue) conduit with the conductors already installed.

I'm not recommending that you do.

steve
 
  #19  
Old 10-31-07, 09:56 AM
Member
Thread Starter
Join Date: Sep 2007
Posts: 35
Received 0 Votes on 0 Posts
Originally Posted by dezwit View Post
Yes, the conduit run should be complete before installing conductors but what is done is done.
A couple of drops of glue are not going to melt the insulation off the wire so don't get too wound up.
Can you pull the wire back a couple of feet before you install the balance of the conduit?
Trying to slide conduit on and then get it into a fixed panel can be quite difficult especially when coming into a hub on the top of a panel.
Are you using a hub of some sort to prevent the entry of water into the panel?
I have decided to change the last 15 feet of conduit so I will have a straight and direct entry into the top of my main panel. I pulled my couductors out from a LB that is upstream from this area. No heat, glue or saws will be near the conductors.
I plan on using a conduit piece called an "expanison fitting" to get a tight fit on the panel. This is an expensive piece that adjusts out six inches or so and takes up the slack while trying to install rigid conduit onto a fixed panel.
Dez, I am not sure what you mean by hub. The exterior of the panel is on an outside wall. It houses the meter socket and driptight door for the breakers.
The back of the panel is on the inside wall and this is where the conduit enters.
 
  #20  
Old 10-31-07, 05:05 PM
Member
Join Date: Oct 2007
Location: Delray Beach, FL
Posts: 406
Received 0 Votes on 0 Posts
I don't see any reason why you can't use the expansion fitting for what you are doing, but it's real purpose is to allow for expansion and contraction of the PVC depending on the ambient temperature of the air.
In a hot environment, PVC will expand to the point that it will rip the straps holding it right out of the wall.
In the cold weather it can contract to the point that it will break the connector where it goes into a meter, box, etc.
When installing it, you pull it apart until you see the line marked on it and that is the size that you fit your pipe to.
If temp is not a problem, don't use the fitting.
If you go ahead and use it, make sure that the female side is facing down to prevent any water from entering and running down into the panel.
The hub I was talking about is a threaded fitting that you use for entry into the top of your panel.
Do you have a round hole in the top of the panel with 4 screw holes around it?
If so, you need to purchase the proper hub to fit the panel.
This is how you keep water from entering the panel.
 
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
 
Ask a Question
Question Title:
Description:
Your question will be posted in: