Bending Grey Electrical PVC Conduit with a Heat Gun
I’m working on installing the electrical along the top of the wall of the initial cutter room (iCutter) in our butcher shop. I’m packing a lot of conduit into a small space since I want each work area to have it’s own outlets for 240VAC3Ø, 240VAC1Ø and 120VAC plus the lighting, lots of lighting for good work areas. Then there’s the switch boxes.
A limiting factor is that I have to pass all the conduit above the rail boxes over the doors and below the curb of the catenary arched ceilings. There is not much space there. About 3.5″x3.5″ at the ceiling-wall coves for five conduits, for of which are 3/4″ inside diameter (1″ O.D.) and one of which is 1″ I.D.
Using premade bends I could not get all the conduit to fit in and then redirect to where I needed. Not elegantly. Not without adding bumps inside from joints that then make pulling wires harder later.
Instead what I’m doing is bending the conduit just a little bit to make the necessary twists and turns to get to the outlet boxes.
Beware that the heat guns do get very hot. Don’t look into the hot end, don’t touch it, don’t catch things on fire, don’t leave it unattended, walk on the grass, void where prohibited and all those standard warnings. (Realistically, if you need these sorts of warnings then consider that you should not be using a heat gun or anything sharp, pointy, hot, explosive, dangerous, etc.)
Here’s how I do it:
- Heat gun such as used for stripping paint. Even a hair drier may work. It isn’t a lot of heat that is needed but rather a steady stream.
- Protective gloves – I use white cotton to protect my fingers while working. Don’t use something that’s going to melt or conduct the heat.
- Metal object for manipulating hot PVC – I used a flat faced hammer or putty knife to press it.
How-to Bend PVC Electrical Conduit:
- Set the heat gun securely on a flat surface. Pick something non-flamable. I use my handy-dandy concrete butcher shop. Locking it down so it doesn’t move is a good idea.
- Slowly rotate the conduit in the path of the hot air from the heat gun. It takes a little while to warm up. You want to warm it all the way around the circumference of the pipe.
- As you rotate experimentally flex the conduit gently. When it gets to the right softness it should become a bit putty like.
- Gently bend the angle you need. It may flatten and flare. This is where the hammer comes in – I use it to press on the sides to keep the tube fully open. Another trick is to put sand inside the conduit but that is messy and this is easier. Careful not to over bend the conduit or make too sharp an angle as it will make pulling wire more difficult and reduce the conduit’s capacity.
- Dunk the PVC section in cold water to set it if you’re aiming for speed.
If you’re doing a lot of the same bend then a jig can help get repeated angles easily. A jig can be as simple as some screws or nails at the angles and flat points in a piece of wood.
The PVC does smell (outgas) so I would suggest ventilating the room while working for your good healthcare.
There is also a trick with using a heat blanket that an electrician told me of today and I saw a photo once of a heating box which is probably along the same lines. So there is more than one way to skin a Cat-5, er, bend conduit.
This reminds me of pulling pipettes. Lots of fun. Dangerous hot glass. Gooy materials if you go too far. Risk of fire, flambé and burns. The nice thing about bending your own conduit is you can do a double twist with a half-gainer if you need it. The mind soars at the possibilities.
So today a master electrician came to check things and go over my questions. I’ve done a lot of wiring, read code, read other books but dealing with the three-phase power is something new and there are some other details of the butcher shop’s electrical installation that I wanted to make sure I was getting right. In addition to answering the questions I had he also taught me a few extra little tricks like positioning screws at the 12 and 6-o’clock position so they drain. Smart.
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