Extension cord wiring diagram

An extension cord also called an extension lead or power extender is a power supply expanding box. It is a lengthy flexible electrical cable with a plug at one end and multiple sockets on the other end. And each of the sockets is independently controllable via separate switches. It is similar to the wiring of a switch box with an extended input supply cable.

To make an extension cord, get an electrical wire with the appropriate length. The length of the cord should be considered, based on the requirements. Try to choose the minimum length as required. Because the length increases the electrical resistance and thereby the copper loss. The increase in length creates a voltage drop across the cord and decreases the amount of power that can deliver by the cord. So, every extra length of cord reasons for the power loss in the conductor. Thus, use a cord length that maintains the requirement but not an excess.

Connect each neutral and earth pole in the sockets in parallel to the main neutral and the earth.  Distribute the phase line to the phase poles of the sockets via individual switches. This arrangement is similar to a 2 switch 2 socket wiring or multi-switch multi-socket wiring.

Usually, the type of all sockets used will be similar to match the plug of the extension cord. Use sockets that suit the load’s plug or use multiple types of sockets.

The wires and the parts of the box should satisfy the power requirements. The cord cable should be used with a proper wire gauge depending on the loads that might be used. Extension cords should have a minimum of 16 AWG. The rated load power should be in the limit of amperes the cord can drive safely.

Also, if available it is recommended to wire in standard color code. Because it helps to identify the lines during wiring and also if any maintenance is required in the future. Commonly phase, neutral and ground connections use red, black, and green colors respectively. The color codes followed may vary with countries, in most countries ground connection has green, but for phase and neutral different colors are used.

Always make sure the extension cord has no overload condition. To protect the cord from over current, install a fuse inside the extension cord for the rated power capability. A fuse can be added in the phase line before the first switch in the circuit. Additional options such as Fuse/Mini MCB, power-on indicator, etc, can be included with the extension box.

Keep extension cord cable protected from physical damages. Make sure it has proper insulation and avoid chances of contact with water or wet surroundings.

Also, the cord should not be rolled or coiled while in use. The coiled structure causes inductive reactance or impedance across the coil and drops voltage across the wire.

Components Required for the Extension cord