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I've just replaced the ceiling rose/pendant in my main bedroom. Although the bedroom light is "working" i.e. turning the bedroom light on/off by its switch, this switch is now also switching the bedroom walk-in wardrobe light which is on a separate switch. Switching the walk-in wardrobe switch also turns off the bedroom light switch. There is clearly some kind of dual switching going on but cannot understand how this could be happening as everything looks like it is wired correctly in the ceiling rose. (Caveat the blue switched/live black sleeve did fall off while doing this so cannot be sure it is wired the same, but given that the bedroom switch is turning the bedroom light on/off....)

The bedroom ceiling rose has three twin and earth lighting cables entering, one obviously from the previous light in the circuit on the same floor, the bedroom light switch cable and the third i'm assuming to the end light in the circuit which is the walk-in wardrobe light.

Any ideas on what could be happening? Thanks

enter image description here

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  • Hello, and welcome to Stack Exchange. Where are you located (for electrical code and standards purposes)?
    – Daniel Griscom
    Jan 12, 2017 at 16:01
  • Sounds like they simply took power for the closet light after the room switch rather than before it. To fix this you would need to run new wire from unswitched power to the closet light.
    – keshlam
    Jan 12, 2017 at 16:07
  • Hi Keshlam,This all worked fine before changing the ceiling rose.
    – drwg
    Jan 12, 2017 at 16:44
  • @keshlam this is the strict UK style of wiring. Blue or black = neutral. They don't have free-form wirenuts, the junction block decides that for you. They leave you just enough space to either wire a downstream always-hot, or a downstream switced-hot, depending on how you use the junction blocks. It can be switched from always-hot downstream to switched-hot downstream by switching two wires, which is what OP did. Accidentally.
    – Harper - Reinstate Monica
    Jan 12, 2017 at 18:13

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Any ideas on what could be happening?

You mistook a neutral for switched live

the blue switched/live black sleeve did fall off while doing this so cannot be sure it is wired the same

Looking at your photo if wired correctly you should have something like

 N-----N----N      L----L----L    SL---SL
 Lamp  in   out    in   out  sw   sw   lamp

Instead you have something like

 (N)----SL----(N)    L----L----L    N---(SL)
 Lamp   sw    out    in   out  sw   in  lamp

The lamp lights because you have reversed its N and L connections and AC bulbs don't care which is N and which L

Switching the walk-in wardrobe switch also turns off the bedroom light switch.

Well, we don't know if the wardrobe is before ("in") or after ("out") the room light. Miswiring the room light as above will affect the availability of neutral at subsequent lights.

There may be some combination of miswiring that accounts for the symptoms you report (though some aspects are not clear from your description)

The solution is to undo all the blue connections in the rose, keep all the blues separate and positively identify every wire (or more specifically, which of the three thicker blues is actually switched-live). You can do this using a suitable voltage tester

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  • Thanks RedGrittyBrick, just came to the same conclusion myself after thinking about it some more.
    – drwg
    Jan 12, 2017 at 17:07
  • @drwg: See Someone answers
    – RedGrittyBrick
    Jan 12, 2017 at 17:10
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You have 4 pairs of wires coming in: supply power, power to the next lamp, the switch loop, and the lamp proper. These steps will require that you turn the power on and off several times at the consumer unit (service panel). Such is testing.

Any intuition or technique you can use to hasten the steps is fine. For instance if you can quickly leap to the end of step 3, great, assuming it works. If it doesn't work, go one step at a time. There may be other problems.

For North Americans following along, brown=hot, blue=neutral, and green=one guess :)

Step 1. Turn off power and disconnect everything. Cap off unused wires until you get through step 2.

Step 2: supply power. Of the three twinned pairs of wires coming into the box, try each in turn, one pair at a time: Connect its brown to the center 3-block, and its blue to the outer 3-block. Energize and test with a voltmeter. If you don't have a voltmeter, connect the two lamp leads also to the same blocks. If 230V, this step is done. If not, de-energise, remove the wires, and try another pair.

The two wires placed so far will stay put for good.

Step 3: downstream power. Turn off this lamp's light switch! And keep it off throughout this step! Of the two remaining twinned pairs, connect one pair in similar fashion to the 3-blocks. Test if the downstream lamp starts working on its switch. If so, this step is done. Otherwise, remove this pair and try the other pair.

Step 4: lamp neutral. Connect the lamp's neutral/blue (it's not in a twinned pair coming from the ceiling) to the remaining open terminal on the neutral block.

Step 5: lamp hot. Connect the lamp's hot to the yet-unused 2-terminal block.

Step 6: switch loop. Connect the remaining twinned pair to the two still-open terminals. These must on the hot/brown block and the 2-terminal block.

And done.

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