PVC Conduit and Fittings
Like PVC plumbing pipe, rigid PVC electrical conduit comes with a variety of union, transition, and bend fittings that make it easy to join lengths of conduit together and connect the conduit to electrical boxes, junction boxes, and other PVC components. Standard rigid PVC electrical conduit is known as “schedule 40 PVC conduit.” It comes in 10-foot lengths and in diameters of 1/2-inch, 3/4-inch, 1-inch, 1 1/4-inch, 1 1/2-inch, and 2-inch. In commercial applications, diameter sizes continue up to 2 1/2-inch, 3-inch, 3 1/2-inch, 4-inch, 5-inch, and 6-inch. The lengths of conduit have one smooth and and one hubbed or bell end. When joining lengths of conduit, you simply solvent-glue the smooth end of one piece into the hubbed socket of another piece. Lengths of conduit can be cut with any saw, but the best way to cut PVC conduit is with a PVC tubing cutter, of the same type used to cut PVC plumbing pipe.
PVC Cement
The “glue” used to join rigid 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 (very rare in residential use), 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 that is 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.
Tools and Supplies You Will Need
PVC conduit and fittings, as required Tape measure PVC tubing cutter or hacksaw Utility knife or emery cloth Indelible marker PVC primer (optional) PVC solvent glue Rags
Instructions
Wipe the outside of the conduit and inside of the fitting with a rag to be sure they are clean. Assemble the entire layout, including whatever transitions or union fittings are required. Once the pieces are dry-fit in exactly the position you want them, draw a straight line running across both the conduit and the fitting at each joint, using an indelible marker. These “registration” marks will make it easy to quickly align the pieces as you permanently glue the joints together. This is especially helpful on complicated runs of conduit, where there are many bends and offsets. The primer will dry almost instantly. As soon as it does, apply a thin but complete coat of PVC solvent glue to both surfaces. Insert the conduit into the fitting and push until the conduit bottoms out in the fitting socket. While continuing to apply pressure, turn the pieces, giving them a 1/4-turn twist. This distributes the solvent glue and ensure the joint is fully covered. If you have made registration marks on the conduit, make sure to align these marks as you twist the conduit. Hold the pieces together for 30 seconds (or for the length of time recommended by the solvent glue manufacturer) until the glue is fully hardened. If there is excess glue around the joints, you can wipe it away with a rag while is it is still wet. Work joint by joint along the conduit run until the entire layout is complete. The conduit is now ready to fish electrical conductors through it.
