The dimmer switch in our bedroom has stopped working properly, so I bought a new simple 1 way switch.

I opened the unit to find 4 brown wires 3 of them wired in to L1 port and 1 in to the C port. Also the earth wire, but no blue neutral. There looks like some sort of loop in the background but I'm a little confused.

Does anyone know what is going on?

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  • 3
    I’m voting to close this question because it should be migrated to DIY.SE
    – Elliot Alderson
    Dec 17, 2020 at 13:16
  • 2
    Your dimmer in in series with the load on the live side. No neutral connected. Same with a switch, it just switches the live.
    – winny
    Dec 17, 2020 at 13:50
  • Thank you winny, much appreciated. Not sure how to proceed to wire a 1 way without a blue, but this may not be the place to ask that. Apologies.
    – Tom Primrose
    Dec 17, 2020 at 14:00
  • Why and where do you expect to connect a neutral to your switch? As winny already pointed out, only live is switched.
    – brhans
    Dec 17, 2020 at 14:49
  • That's a lot of wires for a switch. Did you ever have an overhead fan in the room? Dec 17, 2020 at 16:41

2 Answers 2


Box for light switch may not have neutral, because switch interrupt only live wire. Just two wires to light. Neutral is in lighting fixture. The dimmer designed to replace regular switch. If it has some sofisticated electronics that powered by small current going via light in off condition.


The standard way of wiring a switch is to interrupt only the hot side of the circuit. It's not necessary to also interrupt the neutral and while it doesn't hurt to do so, it would be very confusing to the next electrician to work on this trying to figure out why it was done, so it's best not to attempt to do so.

Modern "smart" switches will require a neutral at the switch because the switch itself needs a full circuit (hot "coming in" and neutral "going out") to form a complete circuit to power the "smart" portion of the switch, but the switch itself only interrupts the hot side of the circuit.

Your blue neutral wires are all connected at the back of the box because you need the neutral at the fixture (light, washer, whatever) to complete the circuit back to the breaker box.

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