When wiring a light switch in the UK, you will often see terminals labelled L1, L2, and COM. These markings indicate how the switch functions within an electrical circuit, particularly in one-way and two-way switching setups. Understanding what each terminal does can help ensure correct wiring and safe installation.
What do L1, L2, and COM Mean?
L1 = Line 1
L2 = Line 2
COM = common
Depending on the position of the switch, either L1 or L2 is connected to “common”—hence the name; it is the terminal that is “in common” between the two positions
What Is COM on a Light Switch?
The COM (Common) terminal is the main connection point on a switch. It is where the live (L) wire from the power source is connected. The role of the COM terminal is to distribute power to the switch mechanism, allowing it to control the flow of electricity to the connected light fixture. In both one-way and two-way switches, COM plays a crucial role in completing the circuit.
What Is L1 on a Light Switch?
L1 means The L1 terminal is where the switched live wire is connected. When the switch is turned on, electricity flows from the COM terminal to L1, sending power to the light fixture and turning it on. In a one-way switch, L1 is the only output terminal, meaning the switch simply breaks or completes the circuit. In a two-way switch setup, L1 works in conjunction with L2 to allow control from two different locations.
What Is L2 on a Light Switch?
The L2 terminal is primarily used in two-way switching systems. In a two-way switch, L2 serves as an alternative output terminal that works alongside L1. Depending on the position of the switch, electricity will either flow from COM to L1 or from COM to L2. This allows a light to be controlled from two separate switches, such as at either end of a hallway or staircase. If you are wiring a one-way switch, L2 is usually not needed and remains unconnected.
Understanding the function of L1, L2, and COM is essential for safe and effective light switch wiring. If you are unsure about any part of the wiring process, consult a qualified electrician to ensure compliance with UK electrical regulations.
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