How to Use Insulation-Displacing Connectors for Electrical Wiring

What are Insulation-Displacing Connectors?

Insulation-displacing connectors (IDCs) are a type of electrical connector used to make connections to insulated solid wire without having to strip the insulation first.

IDCs use sharp blades or teeth that cut through and displace the wire insulation when the connector is actuated, making contact directly with the conductor inside. This allows for quick and easy termination of insulated wires without having to pre-strip the insulation first.

Some key features of insulation-displacing connectors:

• Allow connections to insulated wires without stripping
• Sharp blades cut through insulation to contact conductor
• Create a gas-tight connection and eliminate corrosion
• Available for a wide range of wire sizes
• Used for splicing wires and terminating wires to components
• Common types include fork, spade, and socket connectors

Where are IDCs Used?

Insulation-displacing connectors are commonly used for:

• Electrical wiring - Splicing and connecting solid core building and appliance wiring, such as in junction boxes. Very common for house and appliance wiring with PVC insulated wires.

• Electronics - Terminating insulated wires to solderless breadboards and PCBs. Often used to connect ribbon cables in electronics.

• Telecommunications - Making connections between wires in telecom networks and structured cabling installations. Used extensively for network cabling and telephone wiring.

• Automotive wiring - Used extensively in cars and trucks to connect wiring harnesses and joins multiple wires. Withstands vibration and resists corrosion.

• Industrial controls - Used in PLCs, sensors, electric motors, and other controls to easily terminate insulated control wires.

How Do Insulation-Displacement Connectors Work?

Insulation-displacement connectors work by using sharp blades or teeth to cut through the insulation and make gas-tight connection with the bare conductor:

1. The insulated solid wire is inserted into the IDC terminal hole.
2. The connector is then actuated using pliers or an insertion tool, which forces the contact blades into the insulation.
3. The sharp blades cut through the insulation and penetrate to the bare conductor inside.
4. The blades make secure mechanical and electrical contact with the conductor.
5. The blades also compress the insulation material on the sides, sealing out moisture and contaminants.

This creates a solid, gas-tight connection without having to strip off any insulation material. Mechanical tension between the compressed insulation and the conductor provides excellent electrical contact that won't loosen over time.

Insulation displacement process

Common Types of IDCs

Some common types of insulation-displacement connectors include:

Fork and Spade Connectors

• Used for in-line splicing of two wires and tapping pigtails.
• Come in a wide range of sizes for different wire gauges.
• Require crimping or an insertion tool to activate the blades.

Insulation-Piercing Connectors

• Designed to pierce insulation when mating part is connected.
• Used for connecting wires to screw terminals and posts.
• Require no crimping or special tooling.

IDC Sockets

• Allow termination of PCB headers and ribbon cables.
• Duplicate socket housing but with cutting blades instead of solder cups.
• Require insertion tooling to seat wire into socket.

IDC Splices

• Used to splice multiple wires within electrical boxes and enclosures.
• Available in heat shrink and non-heat shrink versions.
• Quick alternative to using wire nuts.

Best Practices for Using IDCs

To properly and safely use insulation-displacement connectors:

• Use the properly sized connector - Match wire size to the connector's specified gauge range. Undersized connectors can loosen over time while oversized ones may not fully penetrate the conductor.

• Ensure full actuation - Use proper pliers or hand tools to fully actuate the connector and seat the blades. Partial actuation can lead to poor contact and increased resistance.

• Keep wire insertion length short - Wires should be fully inserted but stripped ends should not extend past the connector body more than necessary.

• Pull test connections - Give a firm pull test on wires terminated with IDCs to ensure they are properly secured.

• Use heat shrink on splices - Heat shrink tubing provides strain relief and an extra environmental seal on IDC splices.

• Avoid moving or bending once terminated - Insulation-displacement connections can loosen if repositioned after termination so should be kept stationary.

Using proper IDC connectors for the wire size along with the manufacturer recommended actuation and wiring practices will ensure solid, reliable connections.

Pros and Cons of Insulation-Displacing Connectors

Pros

• Allow termination of wires without stripping insulation
• Quick and easy to use
• Produce gas-tight connections without corrosion
• Vibration and pull resistant
• Widely available in many styles and wire sizes

Cons

• Require proper tooling to actuate and seat properly
• Not reusable or repositionable
• Limited maximum voltage and amperage capacity
• More prone to failure if improperly installed
• Generally higher resistance than soldered or welded joints

Conclusion

Insulation-displacement connectors provide a fast and convenient way to connect insulated wiring without needing to strip the wires. The sharp blades slice through the insulation to make a gas-tight connection with the enclosed conductor when properly actuated. IDCs come in a wide variety of styles for applications ranging from building wiring to electronics assembly. Using the proper size connector and following best practice installation procedures will ensure long-lasting IDC connections.