Wire Connectors: Types and Uses

All wire connector types are designed to create a secure connection between electrical wires and prevent the wires from contacting anything that could create a short. They’re necessary for making any wiring connections, including installation of electrical receptacles, light switches, ceiling fans and light fixtures. You’ll also find specialized connectors for use in wet locations or connections that need to be buried.

Connectors for wires have minimum and maximum wire gauges they can handle, often noted along with the maximum number of wires they can accept. For example, a wire connector might have a minimum capacity of two 14-gauge wires, indicated as “2 #14 wires,” and a maximum capacity of four 12-gauge wires, indicated as “4 #12 wires.”

Other specifications to consider include:

• Maximum voltage and amperage capacities
• Suitability for indoor or outdoor use
• Water resistance
• Suitability for underground use
   

You also need to know the type of wire you’re working with. Standard wire connectors are designed for use with copper wire only — don’t use them with aluminum wire. If you’re working with aluminum wire, make sure the connector is specified for that application.

Most electrical wire connectors you’ll see for residential use are variations of the twist-on connector. The most basic twist-on wire connector is a cap with ridges running down the barrel and an internal square-cut wire spring. The ridges allow a solid grip as you twist the connector onto a set of wires. As you twist the connector, the spring grips the wires and holds them together.

Standard twist-on connectors are the most economical and are easy to install and remove. They’re typically reusable as long as they’re not damaged. These are for connections inside an approved electrical box and are commonly used to install receptacles, switches and fixtures such as lights, ceiling fans and other hard-wired devices.

Wing wire connectors function like twist-on connectors and have similar applications, but they have wings or tabs on the barrel of the cap that make installation and removal quicker and easier. If you have a lot of connections to make, wing wire electrical connectors can be an economical way to make the work more comfortable and reduce hand fatigue.

Weatherproof and waterproof wire connectors are specialized, single-use devices. These twist-on connectors contain a silicone sealant in the cap and protective fins or flanges covering the cap opening to protect the wiring from corrosion, dust and moisture. Common residential applications include installation of exterior outlets, light fixtures and sound systems, but may also include interior projects such as bathroom exhaust fan installations.

Some of these connectors may also be listed as underground wire connectors, suitable for below-ground wiring in applications such as landscape lighting. These direct-bury connectors may use a standard twist-on wire connector that fits inside a protective tube that contains sealant.

Weatherproof, waterproof and underground wire connectors that accept higher-capacity wires are suited for commercial applications like street or parking lot lights and emergency lighting systems.

Push-in wire connectors aren’t as economical as twist-on or winged connectors but allow for very quick and easy connections simply by inserting the wires into the devices. They can reduce hand fatigue caused by the twisting motion required for standard connectors, which is especially helpful if you have many connections to make for a project. Some of these devices have a clear housing that allows you to visually confirm the wires are fully inserted, and some also have a check port you can use to test the connection without removing the connector. Push-in connectors are available with different numbers of ports. If there are free ports on an existing connector, you can easily add to the connection without completely redoing it. Push-in connectors are best suited for solid wire but work with some low-strand-count stranded wire. They work for many copper wire connections where you would use twist-on connectors.

You can remove the connectors by pulling and twisting the wire back and forth until it disengages. Undamaged push-in connectors are typically reusable on solid wire with the same gauge or a larger gauge, but they aren’t reusable if they’ve held stranded wire — strands can become lodged in the connector and prevent a good connection if the device is used again.

While most wire connectors are suitable only for copper wire, you can find connectors designed for use with aluminum wire. Al/Cu wire connectors allow you to make connections with aluminum and copper wire. These single-use connectors have separate ports that keep the wires separated along with an internal sealant designed to resist oxidation of the wires. These connectors require a specialized torque screwdriver to secure the connections with the set screws, but they can be a solution for making aluminum wiring repairs.

Most wire connectors are easy to install, but always follow the manufacturer’s instructions for the wire connectors you’re using. Here are a few general tips:

• Use a wire stripper to remove the insulation from wires. Make sure you match the wire gauge to the correct notch on the tool. Note that stranded wire is slightly thicker than solid wire of the same gauge — many wire strippers have notches labeled accordingly for solid and stranded wire.
• Don’t strip away too much of the insulation. Make sure the stripped portion of the wire is covered by the connector.
• Make sure the wire ends are clean, undamaged and straight.
• After installing a wire connector, pull on each of the wires a bit to make sure the connector is holding them securely.
• Don’t reuse damaged or single-use connectors.
• Don’t exceed the voltage or amperage limit of the connectors.
• Use the connectors only with the material, gauge and number of wires they’re intended for.
• Use the connectors only in the location and application they’re designed for.