I am trying to replace a toilet pull cord switch.

Wiring seems unusual in the sense that there are:

  • 2x brown wires
  • 1x brown wire that is live and by itself
  • 1x yellow/green earth
  • no blue wires

Those are split over to separate cable sheathes.

Connected to the old pull cord switch was: - mirror light - roof light - extraction fan

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Not sure about the whole setup, this new build was sold like (this is in the UK bu the way) that so I'm guessing some cowboys run out of proper cables and just used whatever was around or I'm missing something important about how wiring is meant to be done, maybe especially in the toilet?

Mainly I do not know what to do about not marked neutral wire, right now I am thinking of joining live with live and neutral with those other two brown wires that are not live.

  • Hello, and welcome to Home Improvement. We'll need more info (e.g. what other devices might be connected?). And, please take our tour so you'll know how better to contribute here. Commented Jun 15, 2019 at 12:36
  • How were the wires connected to the old switch? This is crucial information...
    – Solar Mike
    Commented Jun 15, 2019 at 12:38
  • @Solar Mike, no idea my grandfather just ripped it off and then he died. I found it in semi finished state. Commented Jun 15, 2019 at 12:50
  • Is that brown wire that's by itself completely separate from the rest? Commented Jun 15, 2019 at 19:26

3 Answers 3


Twin brown & earth is the right cable type for a switch loop. One brown is live from consumer unit, the other is switched live to lights etc

Fans often have both a switched live and a permanent live, this allows the fan to continue to run 5 mins after the light etc is switched off. It uses a timer built into the fan. This is better for clearing moist air out and reducing chance of mould. The extra brown wire is probably for that extra permanent non-switched live to the fan.

Finding out which brown is which requires using a Cat II or better voltage tester.


My best guess is that the single brown and the longest brown were together on the same terminal (the brown being possibly a supply to the next lamp), while the short brown is the switched supply to the lamp.

The easy one is the yellow/green as that is the earth connection.

Personally, I would use a multimeter and check out exactly what is what and find out which ones go where, even going into the ceiling space to do so. Safety considerations would mean that I isolate all the lighting circuits at the breaker and use the continuity function on the meter.


That looks like what we call a switch loop. Power is delivered to the light, and a branch comes off to the switch.

In a switch loop, one wire is always hot, and the other wire is switched-hot. Since both wires are hot, it's ideal for them to both use hot colors. So Brown and Brown are appropriate.

However, a basic rule is that all related wires must be in the same cable. That loose spare wire is inappropriate. It should not be used. That makes this rather simple. The switch goes between the two brown wires in the same cable.

The loose brown wire is a mystery. Failures inside a cable are unlikely... but if that happened, or if the last guy thought it'd happened, he may have run the individual wire thinking that is allowed. If a brown wire really is bad, you will need to replace the entire cable. - This is not yet required in the UK, but you might be smart to use three core plus Earth cable, so that you would be able to support smart switches in the future.

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