Types of Wire Connectors
Wire connectors are UL Listed fasteners used to make a tight, low-impedance connection between two or more electrical wires in an electrical box. Made of flame-retardant materials, wire connectors prevent wires from contacting other wires or exposed metal surfaces, which could cause a dangerous fault or short circuit.
This guide will explain the different types of wire connectors, so you can feel confident you’re choosing the right connectors for your project.
Wire connectors are available in a variety of sizes and shapes. While their exterior covering is typically made from insulating plastic, their means of connection is a tapered coiled metal spring or interior grooves that thread onto the wires and holds them securely.
When a connector is twisted onto the stripped and twisted-together ends of wires, the wires are drawn into the connector's metal spring and squeezed together inside it. Electrical continuity is maintained by both the direct twisted wire-to-wire contact and by contact with the metal spring or insert.
Twist-on wire connectors are typically installed by hand. They may have external grooves to make them easier to handle and apply. Wing-like extensions are commonly molded into higher quality connectors to make attachment easier. Such extensions also allow these connectors to be installed with a common nut driver or a specialized tool.
Twist-on wire connectors are:
- Commonly color-coded to indicate the connector size/capacity.
- Frequently used as an alternative to terminal blocks or the soldering of conductors together, since they are quicker to install and, unlike soldered connections, allow easy subsequent removal for future modifications.
- Not often used on wire gauges thicker than AWG #10 (5.26 mm²), because such solid wires are too stiff to be reliably connected with this method. Instead, set screw connectors, clamps or crimp connectors are used.
- Typically used in electrical wiring systems for light switches, receptacles, ceiling fans, can lights, thermostat controls, HVAC, smoke/CO detectors, garage doors, door bells, security systems, recessed lighting, signage and more.
Wire connectors come in seven main designs, each tailored to a specific purpose.
Tip: Some electricians prefer crimp-on wire connectors for joining ground conductors in an electrical box.
Like most twist-on connectors, winged connectors don’t require pre-twisting wires, but the practice is recommended. Winged connectors speed up the attachment process, allowing for a better grip and making ideal for large projects requiring multiple connections. They make fast, easy to use, secure electrical connections, and the connectors can be removed easily and reused in most cases.
Crimp-on wire connectors are typically made of steel or copper, and they require a crimping tool to attach correctly. They are designed for making permanent, pressure-type connections and are therefore not reusable. Crimp-on connectors afford a very secure connection. Plastic cap insulators can be used after the connection is made.
Both underground and waterproof wire connectors are typically filled with 100 percent silicone sealant and serve to protect against moisture and corrosion. They are easy to apply and are typically not reusable. Underground wire connectors are usually used for buried electrical cables and are slightly more durable.
Underground connectors or waterproof connectors are often found in sprinkler systems, outdoor pet containment systems, low-voltage outdoor lighting and similar applications.
As an alternative to twisting wires together, some electrical work can be completed with push-in wire connectors. The push-in design eliminates twisting, reducing repetitive motion fatigue, particularly on jobs that require numerous connections.
The wires push into the connector securely and the clear shell gives visual verification of the connection. It can also make it easier to spot a loose connection when undertaking a repair. The compact size of the connector typically takes up less space in an electrical box. Most connectors can easily be removed by pulling or twisting conductors, and the connectors generally can be re-used.
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