Heating PVC for bending purposes

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jap said:
You'd have to dig it up out of the ground to find out now wouldn't you. :p


JAP>
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depends. There is one Electric utility I can think of that requires you to pull a mandrel through their conduit in front of them before they pull wire.
 
JFletcher said:
While we're on the subject, is there any code that limits the amount of tension in a conduit from bends? With smaller conduit, one can simply glue a joint that isnt perfectly aligned, bend the conduit while under tension then secure it with straps. With larger, it seems to me that any slight misalignment is usually taken care of by the small amount of slop in the joint, i.e., the joint is crooked

Also, anyone have a link to the plugs/plug kit one would use with compressed air?
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Greenlee 859-4 and as stated before you don't need compressed air. In fact you have to relieve the pressure of the heated air inside before taking the plug out.
 
Strathead said:
depends. There is one Electric utility I can think of that requires you to pull a mandrel through their conduit in front of them before they pull wire.
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And I take it if the mandrel comes out oblong they point at you and say "So your that guy that gives PVC a bad name" ? :lol:

JAP>
 
jap said:
And I take it if the mandrel comes out oblong they point at you and say "So your that guy that gives PVC a bad name" ? :lol:

JAP>
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No, the mandrel won't pass through and has to be pulled back out. Then YOU have some digging to do.

Never did the sand thing but I have done bends both with just plugs and with compressed air. Yes, I know that the temperature rise will result in an increase in the air pressure within the conduit. But what I found is that the plugs do leak and you won't know that until you make your bend and it kinks. So as not to waste a length of 4", I grease the plugs lightly to ensure a seal then I have an air tank fitted with an instrument regulator that is self relieving. Put about 5psi in there and if it holds go ahead and heat it. When the pressure rises the regulator relieves it and maintains the 5psi. Maybe this seems like a lot of work but when you are doing exposed work you get bends that equal those from the factory.

-Hal
 
hbiss said:
No, the mandrel won't pass through and has to be pulled back out. Then YOU have some digging to do.

Never did the sand thing but I have done bends both with just plugs and with compressed air. Yes, I know that the temperature rise will result in an increase in the air pressure within the conduit. But what I found is that the plugs do leak and you won't know that until you make your bend and it kinks. So as not to waste a length of 4", I grease the plugs lightly to ensure a seal then I have an air tank fitted with an instrument regulator that is self relieving. Put about 5psi in there and if it holds go ahead and heat it. When the pressure rises the regulator relieves it and maintains the 5psi. Maybe this seems like a lot of work but when you are doing exposed work you get bends that equal those from the factory.

-Hal
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Bummer.

I'd say anyone who cant bend PVC without a mandrel hanging up in it after they're done needs the plug,heat and air setup.


JAP>
 
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If heating PVC was not an allowable option, the PVC Hotbox would not be as popular as it is. Now, you have to observe great caution when heating the PVC not to over do it, kink it, or try to bend it into a pretzel that is later impossible to wire. You have to adhere to the requirements of NEWC 352.26.


Carlos B said:
Is heating PVC conduit allowed per code? I need to do some bends coming up into a concrete column that will have a cage in it. If I can heat and bend the 1" PVC I can install fairly easy and quick. I looked in the 2014 code book but did not find anything that said I could do it or not. Does anyone have any insight into this?

Many thanks
CB
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hbiss said:
So you are OK with egg shaped bends? It's guys like you who give PVC a bad name.

-Hal
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I have seen many factory elbows that are egg shaped, and bell ends that are not round as well quality control isn't the same as it was 25 years ago.
 
kwired said:
I have seen many factory elbows that are egg shaped, and bell ends that are not round as well quality control isn't the same as it was 25 years ago.
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Bending PVC for me is not difficult and doesn't take special tools other than maybe a pair of gloves, a hot box and a wet towel.
I'm old fashioned and can bend it without the need for all the new fancy things they have now days.

If people want to use the plugs and air and sand and flex and whatever so be it.
In my mind it's making a mountain out of a mole hill.

Cant recall once in my career where I ever had to dig one up or where I couldn't get the wire through them and I've been doing this a long time and have installed a ton of underground pvc.

I guess I'm just good at it. :)


JAP>
 
jap said:
Bending PVC for me is not difficult and doesn't take special tools other than maybe a pair of gloves, a hot box and a wet towel.
I'm old fashioned and can bend it without the need for all the new fancy things they have now days.

If people want to use the plugs and air and sand and flex and whatever so be it.
In my mind it's making a mountain out of a mole hill.

Cant recall once in my career where I ever had to dig one up or where I couldn't get the wire through them and I've been doing this a long time and have installed a ton of underground pvc.

I guess I'm just good at it. :)


JAP>
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I can mostly say all the same things you did.
I suppose you can bend a tighter radius more easily if you can find some method to support the inside, I generally don't try to bend too tight though.
 
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