My Grandma has an outdoor spotlight that hasn't worked for quite some time. I realised there wasn't actually a bulb in it so I ordered a new one, switched off the mains, fitted it, put the power back on, and it works, the light comes on! There's only one problem - it won't switch off again!

Here is a picture of the outdoor spotlight:
Outdoor Spotlight

There is also this light indoors above the front door:
Indoor Light

Years ago, I remember that when the outdoor spotlight was triggered by someone approaching the door, the bulb indoors would light up as well. However, both bulbs are just permanently shining and I can't figure out why. My Gran has since forgotten why the bulbs were removed from the outdoor and indoor lights, or how they've gotten like this.

An initial Google of how to fix the problem mainly returns results saying to switch the spotlight on and off again rapidly to reset the sensor. However, I can't actually find a switch for it, and I believe it is wired directly into the mains. I did find this cover in the upstairs bedroom shown in the first photo which is directly behind the spotlight and I'm 99% sure this is the wiring for it but it's just that, wiring, and not an on/off switch.

Any help in remedying this would be much appreciated!

  • 1
    This is anecdotal, so not making it an answer, but I had this happen once, and we discovered there were spiders living inside the housing for the motion sensor, which were constantly setting it off. Might be worth checking if there's something living in there. May 11, 2020 at 17:06
  • It’s unlikely for the capped switch to be in an upstairs bedroom. To test, turn off the power and disconnect the wiring, and see if the light is off. Be safe as you do this - keep everyone away from the temporarily live exposed wiring.
    – Tim
    May 11, 2020 at 17:56
  • 1
    @Darrel Good heavens, that sounds horrific, I think I'd rather buy a new one than chance a 4-D screening of Arachnophobia, but thanks for the tip!
    – Nemon27
    May 11, 2020 at 19:52
  • @Tim It is highly unusual for the switch to be where it is, upstairs in a bedroom near the skirting board, but these definitely are the wires for both the spotlight and light above the door, I tested them both turning the mains power off and on as required to stay safe. I believe it was originally installed and wired by a jack of all trades family member rather than an electrician which led to the initial question and confusion.
    – Nemon27
    May 11, 2020 at 19:52
  • I do like the idea of a light in the hall being switched on when the security light triggers, although that ought to be switchable separately, which it probably isn't. Probably not feasible now, as it would need two way switching, and there's probably no extra wire in the circuit. Agree the unit has failed, and it needs a switched fused spur on the wall in the bedroom. 5 Amps max.
    – Tim
    May 12, 2020 at 7:47

7 Answers 7


I believe the key words here are "years ago" and "motion sensor". Motion sensors don't generally live that long. It may be time for a new fixture, or if modular, a new motion sensor.

  • 2
    After attempting to reset it all different kinds of ways I have settled on just buying and fitting a new one for her, you are right it has definitely worn out after years of use. Although props to @EdBeal for suggesting how to wire a switch into it with the wires that I found - they definitely control the lights and after some messing I have put a switch on there so they can be turned off completely if need be.
    – Nemon27
    May 11, 2020 at 9:22
  • You've probably done this already, but if not: consider labelling the switch, so that in years or decades to come, you or your successor doesn't have the same question! (When I moved into this house, there were a couple of switches that took some head-scratching to identify.)
    – gidds
    May 13, 2020 at 13:49

I agree with Harper's comments, and this is strongly supported by your own statement

"My Gran has since forgotten why the bulbs were removed from the outdoor and indoor lights..."

It is most likely that the sensor broke a long time ago, and your Gran - either herself or perhaps asking someone else to - removed both bulbs because they were permanently stuck on, day and night - and rather than get it fixed at that time, "the problem" was removed. You have simply highlighted the old problem. Maybe your dad could shed some light on this.

If obtaining replacement parts (or an entire unit) from the same manufacture is impossible, maybe its time to remove the entire configuration and go back to a basic light switch system.


Some motion lights need to be reset, and a quick on off on some models will turn them on while a longer off on cycle may turn it off. It's also possible the sensor has failed. Removing the brown wire going to the fixture will remove the power to the light, the red is normally the output from the sensor, and the blue is neutral or the return. If you add a switch on that brown 1 side going to the switch the other side going back to where the brown was connected, you could control it with the switch. Make sure to make any changes with the power off.


A lot of early security lights (and some modern ones) have a feature whereby if you flick the power off and then back on within a few seconds the light will stay on permanently. To make it work normally (switched by the proximity sensor) the power needs to be off for at least 10seconds before going on again. The problem was that a momentary supply glitch would result in the light being on permanently. I agree with comments about broken ring, fused spur, sleeved earth etc.


When you turned off the power did you just turned off the power main power if so then flip it off and back on very quickly if it is the lights that need resetting. Then that should work. Cheers. GT


Ok... Add a switch. I suggest a 13a switched fused spur unit. But you put a 5a fuse into it.

Really this should have been done when fitted.

Both of the blue /brown / earth wires at the top look to be part of a ring... Which has been broken! (Turn the main incoming power off at the consumer unit and do a continuity test to confirm.)

Put both of the load wires into the load side of the fsu, and both supply lines into the supply side of the fsu.

You can use those terminal blocks and cut some short jumper leads to the terminals if it's tight.

But since you don't know this basic thing ( and you're therefore not legally competent) I'd suggest getting a sparky, ... Electricity kills.

Most sparks only charge about £40 to fit a socket ... This shouldn't be any more difficult.

Also. If this isn't on a rcd circuit, you will need an rcd fsu. All outdoor wiring has to be on an rcd protected circuit.

Also note that those earth cables should have sleeves. It's only about £1.50 in bnq for 5m


Hi that light should have been fitted with a fused spur with switch and 100per cent pir has failed due to weather conditions you can then fit a light switch in hall way Allways turning your light power off

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