I want to put LED lights in the kids' bedrooms and have fitted the coving, the lights have 3pin plug 200-240v 50/60HZIP20 transformer built into plug 12V 3AMP. My problem is I need to fit a double socket. However there are no sockets I can spur off in the loft. The only supplies available are the lighting circuit or the smoke alarms which are daisy chained back to consumer unit.

The question I have is: can I take a spur of the lighting circuit or the smoke alarm and fit a double socket for the LED lights? Any advice would be appreciated.

From comments: This is in the UK.

4 Answers 4


You cannot put regular 13A mains sockets on a lighting circuit in the UK. Lighting circuits are not designed to take a full 13A. They are not rings, which most of your 13A mains is, so the wiring is not up to the task.

You might be using them for lighting, but someone else in future may not. It would be safest to lift the power supplies into the ceiling, hard-wired into suitable junction boxes & drop actual light switches. Leave a note in the switch as to what is being done in the ceiling. This is still 'cheating' a bit, but at least no-one can ever plug an electric fire in it.

  • 3
    And this is why I said "refer to local codes & regulations" about 20 times in my answer!
    – FreeMan
    Feb 17, 2023 at 17:39
  • Yup. It just makes my teeth squeak when I hear about US mains with lighting & sockets on the same spur/star config. We often use the same 'weight' of cable for lighting as ring main, but the ring structure itself means the same cabling can take a lot more power than a spur. Lighting is almost never on a ring, it doesn't have to be, which makes it very iffy for sockets… apart from the fact they're not 'fused' for 13A either.
    – Tetsujin
    Feb 17, 2023 at 17:48
  • 1
    The only problem here with outlets & lights on the same circuit is if your toaster, microwave & coffee maker trip the breaker, they take the lights with them, leaving you in the dark.
    – FreeMan
    Feb 17, 2023 at 19:35

While electrical lighting codes vary by location, here in the US, hard-wired smoke detectors need to be on their own circuit so nothing else can cause a breaker trip that could cause them to loose power, becoming a life-safety issue. Even if that isn't the case where you are, it does make sense, so I would consider that circuit is right out.

That leaves you with a lighting circuit as an option to extend to use for... more lighting. That certainly seems like a reasonable option to me.

These are plug-in lights, though, and someone in the future may decide to plug something else into those receptacles, so you probably need to check your local building/electrical codes to ensure that this is legal. (You haven't told us where you are, but I'm guessing somewhere in the UK or a strongly UK-influenced area of the world, however, it could vary from England to Scotland, or more if you're farther afield than that.)

Bonus tip: As a general rule, more receptacles are better than fewer. If your local code does allow general purpose receptacles on a lighting circuit, then you may want to consider adding several additional ones while you're at it. This will allow the kids to plug in USB chargers, etc. in their room. Bare in mind, though, that if something plugged in trips the breaker back at the consumer unit, you're leaving the room in darkness, so this may not be a good idea. Fuses in the plugs may protect you in this case, it may not. Again refer to your local codes and customs.

  • Thank you for your advice, yes i am in the UK(England) will look to see where i can find the local codes. Thanks again Feb 17, 2023 at 12:44
  • Glad you found it helpful, @MalcCoombes. If you'll take the tour, you'll note the proper way to say "thanks". Also, since this is a matter for local code, it's technically off-topic here. ;)
    – FreeMan
    Feb 17, 2023 at 12:45
  • “here in the US, hard-wired smoke detectors need to be on their own circuit” Uhh what? You got a code cite for that?
    – nobody
    Feb 18, 2023 at 14:00

Yes, you can put a 13A socket on a lighting circuit. It's permitted by the IET Wiring Regulations, which do allow plugs and sockets for lighting. Since it's now a circuit with sockets, it will need to be RCD protected, if not already. It's a really good idea to label the sockets, as otherwise someone could plug any appliance in there.

If the lighting circuit is correctly designed, then there is no safety hazard. If someone does try to plug in an electric heater, the circuit breaker wil trip.


Glad you stated where all this is!

It would seem, given that the transformer has a 3-pin plug, just like most of UK appliances, that it would be plugged into a 13A socket. That, so far, makes sense. Mainly as said plug would go into a socket on a ring main, capable of carrying ~30 Amps. And the transformer pulls nowhere near that, let alone 13A.

BUT - Anyone seeing a 13A socket assumes it will be safe for plugging any 13A appliance in. Like an electric fire, for example, capable of pulling all those 13Amps.

That's where the problem starts: the wiring it's attached to, if you go ahead, isn't enough to carry that - it's only for lighting, and were you to do this, someone in the future may plug all sorts in, causing a fire at least. If they were lucky, the lighting fuse/trip on that circuit should blow, which would prevent a tragedy, but then they would need to work out what the problem actually was. O.K. for you, but anyone else living there in the future..?

For me, I'd use a junction box, having cut off the 13A plugs, into the lighting wiring. But you may not be happy doing that, and if the lights needed to be returned, the guarantee has been forfeited. In any case, strictly speaking, a qualified sparky should be doing work on electricity in U.K.

AFTERTHOUGHT: if the transformers have built-in prongs, acting as the plugs (wallwarts), then they will need changing for ones with wires.

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