PVC conduit and fittings are extremely popular, both because they are inexpensive and easy to cut, but also because making the connections is very easy using PVC solvent-cement. A properly done cemented joint is permanent and both airtight and watertight, and it takes less than a minute.
The "glue" used to join PVC conduit and fittings is officially called PVC solvent cement. It comes in a small metal can with a twist-off cap, and is the same material used to join PVC plastic plumbing pipes and fittings. The cap includes an applicator sponge attached to a wire stem. A small can of cement has an applicator pad suitable for conduit up to about 3 inches in diameter. For conduit larger than 3 inches, it's better to use a large can, which has a larger applicator pad.
There are several types of solvent cement available for different types of plastic, so make sure to buy a product designed for PVC. There are also "universal" solvent cements available that claim to be suitable for all types of plastics. Avoid these, and buy one that is intended for use with PVC pipe only.
Is Primer Necessary?
When gluing PVC plumbing pipe, plumbers typically use a primer before applying the PVC cement. Primer cleans and dulls the surface of the pipe to promote bonding. It's fine to use primer with PVC electrical conduit, but many electricians skip this step unless it is required or recommended by the conduit manufacturer or by the local building authority. There is no reason you can't use primer, though.
How to Cement-Glue PVC Conduit
- Deburr the cut end of the conduit, using a utility knife or emery cloth. This removes any small fibers that may have been left when the conduit was cut.
- Wipe the outside of the conduit and inside of the fitting with a rag to be sure they are clean.
- Apply a thin, even coating of PVC primer (if using it ) to the outside of the conduit and inside of the fitting, coating the entire area that will make contact.
- Apply a coating of PVC cement to the same areas.
- Insert the conduit into the fitting and push until the conduit bottoms out in the fitting socket. Keep pushing the pieces together and give the fitting or conduit a 1/4-turn twist, then hold the pieces together for 30 seconds (or as recommended by the cement manufacturer).
- Do not stress the joint for 30 minutes, or as recommended.
Tips for Gluing PVC Conduit
If the conduit or fitting is already fixed (can't be moved) and the parts must have a precise orientation after they are glued, use the plumber's trick of dry-fitting the parts and make a registration mark across the pipe and fitting with a marker:
- Once the pieces are dry-fit in exactly the position you want them, draw a straight line that runs across both the conduit and the fitting, using an indelible marker.
- Pull the pieces apart, apply the cement to the fitting and the conduit, then fit them together.
- After making a 1/4 twist to spread the cement, align the pieces so the registration marks align again into a straight line.