- Written by Super User
Published on 25 July 2013
2-wires and 3-wires Lighting Systems
In order to understand the difference between 2-wire (the most popular one) and 3-wire lighting system we need to have a look at the neutral cable. The 2-wire lighting system does not have the neutral cable at the switch while the 3-wire lighting system does. Please compare the below pictures to see the difference.
2-wire lighting system diagram
A standard 2-wire lighting circuit is shown in above diagram. The brown wire is Live (also know as permanent live), this brings the live supply to the switch. The blue wire is known as the Switched Live and takes power to the light once the switch in in ON position, otherwise the circuit is broken (OFF position) and there is no power in the blue wire.
Note - the switched live (blue wire) has a brown sleeve on it, this highlights that the wire is actually a live wire, this ensure that it is not confused with a neutral wire. If you have a 2-gang or 3-gang switch you may have black and grey wires, however these will have a brown sleeve on them as they are also switched live wires.
3-wire lighting system diagram
An example of a 3-wire lighting circuit is shown above. One '2-Core + Earth' cable takes Live and Neutral to the switch back box, a second cable takes the Neutral and Switched Live to the light. Note - the Neutral is not connected to the actual switch, the two Neutrals are connected together using a connector block.
In order to find out your lighting system you need to check the following:
- are all the wires connected to the switch ?
- do the wires have brown sleeve on them ?
- are there any other wire colors (grey, black) that are connected to the switch?
If you answered YES to the first two questions then most likely you have 2-wires ligthing system. If you answered Yes to the third question then you might have 3-wires (no that popular) lighting system. You need to confirm that with the voltage meter (multimeter) or ask local licensed electrician for advise.