PVC conduit questions

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Old 02-20-17, 07:47 PM
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PVC conduit questions

I have two questions regarding SCH80 PVC conduits.

(1) Is it OK to use plumbing pipe PVC primer and cement (Oatey brand) on the gray color electrical conduits or do I have to use PVC cement specifically sold at electrical section of a hardware store. I have been using them for PVC conduits but recently a home inspector (not a plumber or electrician) told me it's a bad idea but can't tell me why. Just thought I ask to make sure, PVC is PVC is PVC right?

(2) I had a situation where I needed to offset a 3/4" SCH80 PVC conduit for 2". I read that you can heat up the PVC with a heat gun and put sand in it to make sure it won't kink up. I experimented with a heat gun, no sand, just hovered the heat gun 1" away over the portion I wanted to bend back and forth and I end up being able to make the offset bends. However, the portion I put the heat gun on caused the conduit to turn brown in color. See pictures. Are the brown spot OK once it cooled? I tried to redo it with the heat gun further away about 2". but that didn't heat it enough to soften it. So both samples I tried have these brown spots. Still OK to use?



 
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Old 02-20-17, 08:12 PM
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Clear PVC cement will work fine, but not sure if there is any code regarding it.
They use same solvent and only difference I think is it contains same sunlight resistant gray PVC used making conduit dissolved into the solvent.
If it is getting inspected, I'd use gray cement to be safe. But clear cement will glue and cement conduit just fine.

Burnt PVC is ok as unless it is burned black.
It takes patient to heat conduit without burning. Use heat gun or propane torch (MAPP is too hot) far enough not to burn and move around fast.

There are special tool (sort of oven) for heating conduit, but it is expensive and probably not worth it unless you use it everyday or working with large conduits.
 
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Old 02-20-17, 08:35 PM
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told me it's a bad idea but can't tell me why.
I could not find a definitive answer except that the gray glue is specifically made for the electrical PVC. Basically... that's just the way it is.

Even with a "hotbox" it's easy to burn the PVC. It takes the "right" touch.
 
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Old 02-21-17, 05:33 AM
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the gray glue is specifically made for the electrical PVC
Only gray PVC cement that specifically say it is for conduit is specifically made for the electrical conduit. Usually manufactured by the conduit manufacturer.

Gray PVC cement from most other manufactures (ie. Oatey and Weld-On) says it can be used for all PVC pipes including portable water and pressure pipe.

Oatey's gray PVC cement says:
Recommended for potable water, pressure pipe, conduit and DWV.
PVC Medium Gray Cement | Plastic Pipe Cements & Primers | Oatey

Oatey's clear PVC cement also says:
Recommended for potable water, pressure pipe, conduit and DWV.
PVC Regular Clear Cement | Plastic Pipe Cements & Primers | Oatey
 
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Old 02-21-17, 09:39 AM
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You can use any PVC cement on the electrical conduit. It's OK to make custom bends using whatever heat source you find convenient. Try not to narrow the conduit when making the bend. I usually just use a pair of heavy leather gloves to form the pipe using my hand after heating it over a torch. It occasionally gets a little discolored - no big deal.
 
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Old 02-21-17, 02:48 PM
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There are factory bends that can be used for offsets etc.
Geo
 
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Old 02-21-17, 06:05 PM
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I am not worried about appearance since this section of pipe will be behind walls. As long as the slightly burnt section won't disintegrate or crack easily due to the excess heating. It's not out of round or narrowed as far as I can tell.

May be because it's SCH80 it takes longer time? I will try again tomorrow another piece and see. If I can't acquire the right touch I am moving forward with it.
 
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Old 02-21-17, 06:08 PM
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I needed to offset 2" in less than 24" of length for a 3/4" PVC conduit. I didn't see anything other than 45 or 90 elbows at my big box stores. The only other thing I could use is a "flex" connector but I'd rather not. May be electrical supply stores carry 11-1/4 or smaller elbows? The "offset" conduits I saw are too small it is shifting less than an inch I really don't want to piggy back several of those in series.
 
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Old 02-21-17, 07:23 PM
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I will try again tomorrow another piece and see. If I can't acquire the right touch I am moving forward with it.
Try portable propane or butane stove or gas stove in kitchen if the pipe is short enough to bend in your kitchen. I found they work better because the flame is not focused like the torch is.
I found this by accident when my propane torch ran out of gas and had portable butane stove at the job site.


You are probably having problem with heat gun because it does not put out as much heat as propane and you will tend to focus heat in one place as result.

PVC conduit is paintable. So, if don't want to any burn marks, you may choose to paint it gray or same color as the wall (or whatever it is installed on).
 
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Old 02-21-17, 08:10 PM
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Two ideas never tried. Insert a length of greased armoured cable in the conduit then heat over a barbeque grill constantly turning til it is pliable.

Okay a third never tried idea. Cut four pieces of " plywood to the final shape. Fasten two of them on top of each other to make two 1"thick cutouts. Fasten the two pieces about one inch apart to a board so you have a trough to lay your heated pipe in as you bend it.

As stated Never Tried, just suggestions.
 
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Old 02-23-17, 10:36 AM
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I've used the torch method a number of times successfully on up to 1" PVC conduit, without scorching, but the best method is a heating blanket. They can be a bit expensive, but last for years. If you shop around you can probably get one at a good price.

https://www.amazon.com/Gardner-Bende.../dp/B000N50NGI
 
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Old 02-23-17, 05:37 PM
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Since PVC becomes pliable at a temperature just above 212 degrees, you might try this. Get a container that you can place a 24 inch long piece of PVC into. Cover with water and heat water to boiling. Prior to cooking the PVC, make a bending jig out of plywood and pieces of 2x4. Make parallel lines (diameter of PVC) such that you get the 2 inch offset in less than 24 inches ( the greater the distance is between the 2 bends, the easier it is to pull wire through). Make sure the ends are vertical with enough length to allow for coupling to next piece of PVC. Screw pieces of 2x4 to the plywood at the parallel lines such that the PVC is constrained during the bending. Once the PVC is cooked , force it into jig and wait until it is cooled. Connect the homemade offset to the PVC continuing at each end. If you try this, let us know how it worked.
 
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