EMT Conduit Fittings Guide

Conduit fittings, including couplers and connectors, are used to connect one piece of electrical metal tubing (EMT) conduit to another, or to connect conduit to an electrical box. These fittings are available in a variety of materials, sizes, and configurations designed for different uses, from indoor-only applications to fittings that are rated as rain-tight and approved for outdoor use. This article will review the various types and styles of fittings, as well as the basic steps needed to connect conduit to another piece of conduit or to a box or enclosure.

There are two main types of conduit fittings: connectors and couplers. Couplers (or couplings) are used simply to connect two pieces of conduit together. Couplers are available in different styles and sizes and allow you to form longer runs of conduit.
Conduit connectors, on the other hand, have one threaded end and are used to connect a piece of conduit to an electrical box or enclosure via a locking nut. These are sometimes referred to as male adapters.

You'll want the size of your couplers and connectors to match the size of your conduit, but both types of fittings also come in different styles. In fact, both couplers and connectors are available in set-screw and compression styles. 

Set-screw fittings are typically faster and easier to install and can also be stronger than compression fittings. However, set-screw couplers and connectors are not rated as rain- or liquid-tight and must only be used indoors. Set-screw couplers are clearly identifiable by the screws that are used to tighten them—they may have one or more screws, depending on the conduit size.

Compression fittings are frequently rated for both indoor and outdoor usage and tend to provide a tighter fit—though you should still ensure that the couplers and connectors you're using are rated for your specific applications, as not all of these fittings are technically rain-tight. At the same time, compression fittings also take longer to install and may have a higher failure rate than set-screw fittings over time.

Once you've determined the right type of conduit fitting and the appropriate style for your use case, you're ready to connect the conduit to either your existing run of conduit or to your box or enclosure. If you're using a coupler to join two runs of conduit together, here's how it's done:

1. First, slide the piece of cut conduit into one end of the coupling until you hit the natural stop. (Most couplers have a natural stop where the conduit will be seated, preventing it from going further into the fitting.)

2. Take the other piece of conduit that you're connecting and slide it into place on the opposite end of your coupler in exactly the same way.

3a. If you're using a set-screw coupling, tighten the set screws using a screw gun or driver. You're good to go!
3b. If you're using compression couplings, use a pair of locking pliers to tighten the glands of the compression coupling. Once properly tightened, the coupling's gland will compress against the conduit, forming the necessary strong seal.

Using a conduit connector (or male adapter) to connect your conduit run to an electrical box or enclosure? Follow these steps:

1. Most electrical boxes have pre-made "knockout rings," which are essentially just removable, circular plugs covering a threaded hole in the side of the box—perfect for fitting a conduit and connector! Pop one of them out using a Phillips screwdriver. Once you've used the screwdriver to loosen the knockout ring, you can remove it with your hand.

2. Insert the threaded end of your connector into the hole you've created in the box. Once it's inserted, affix the lock nut over the threads on the reverse side (inside the box) and tighten it against the box's edge.

3. Next, slide your conduit into the other end of the connector until it is seated.

4a. If you're using a set-screw connector, tighten the set screws using a screw gun or driver. You're good to go!

4b. If you're using compression connectors, use a pair of locking pliers to tighten the glands of the compression connector. Once properly tightened, the connector's gland will compress against the conduit, forming the necessary strong seal.

Just as there are many types and sizes of conduit available, there is no shortage of different types and styles of connectors and couplings. Though we haven't comprehensively covered every type of fitting here, this guide should help you get started with most applications when it comes to extending your conduit runs or connecting conduit to an electrical box, enclosure, or panel. As always, ensuring that you have the right tools, connectors, and fittings will ensure that your electrical projects are completed with safety and precision.

The product statements contained in this guide are intended for general informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand and follow all manufacturer instructions.