Outdoor Sockets for Christmas Lights: A Rotherham Electrician’s Guide

Every year, around the middle of November, the same picture starts appearing on streets across Rotherham. An extension lead snaking out of a front window, the window held slightly open, and a string of lights plugged in somewhere under a plant pot.

I get it. But that trailing lead is one of the most common electrical bodges I see at this time of year.

The good news is that a proper outdoor socket is usually a straightforward job. The catch is timing. December is a busy month for us, so the earlier you sort it, the better.

Quick answer

The safest way to power outdoor Christmas lights is from a weatherproof outdoor socket with 30mA RCD protection, fitted by a qualified electrician. Look for a socket rated around IP66 with the lid shut, use lights marked as suitable for outdoor use, and keep plugs and transformers out of the rain. Book it in October or early November, before the December rush.

Why the extension lead through the window is a bad idea

Trapped and crushed cables

Close a window or door on a lead and the cable gets pinched. Over a few weeks the sheath can split and the insulation inside can be damaged, often where you can’t see it.

Water getting in

Indoor extension leads aren’t designed to sit outside, and their plug and socket connections are open to the rain.

Trip hazards and draughts

A lead across a doorway is easy to catch with your foot in the dark. The door or window can’t close properly either, so seals get squashed, cold air gets in, and a window left on the latch for weeks isn’t great for security.

What is a proper outdoor socket?

An outdoor socket is a weatherproof socket fixed to an outside wall, wired back to your electrics inside the house. It has a sealed box and a hinged lid that closes over the plug.

IP ratings explained simply

You’ll see outdoor sockets marked with an IP rating, like IP66. IP stands for Ingress Protection and the two numbers tell you how well the box keeps things out.

• First number: protection against dust and solid objects. A 6 means dust tight.
• Second number: protection against water. A 6 means it can cope with powerful jets of water.

Here’s the bit people miss. Many outdoor sockets are only rated IP66 with the lid closed and nothing plugged in. Once a plug is in and the lid is propped open, that protection drops.

In use covers

For things that stay plugged in for weeks, like Christmas lights, I usually recommend a socket with an “in use” cover. The lid closes over the plug, with the cable coming out underneath.

RCD protection

An RCD (residual current device) switches off in a fraction of a second if current leaks away, for example through water or a person.

Outdoor sockets should be protected by a 30mA RCD, and Electrical Safety First’s Christmas guidance says outdoor lights should be connected through a 30mA RCD protected socket. If your house still has an old fuse box with no RCDs, that’s worth looking at first. I’ve written more about this in our guide to RCDs, RCBOs, AFDDs and surge protection.

What can a 13A socket actually take?

A standard UK socket is rated at 13 amps. On a 230 volt supply, that works out at roughly 3,000 watts (3kW) in total. That total is shared between everything plugged into that socket, including anything on an extension lead or adaptor.

Daisy chained extension leads

Plugging one extension lead into another is a recipe for overloading. Warm plugs, a hot plastic smell or scorch marks around the pins are warning signs.

Electrical Safety First advises avoiding extension leads and adaptors where you can, and not overloading sockets. A proper outdoor socket, or a double outdoor socket, cuts down on the need for them.

LED lights use very little power

Electrical Safety First says LED Christmas lights use 80 to 90% less electricity than old filament bulbs. A typical string of LEDs is often just a few watts, so on their own they’re very unlikely to trouble a 13A socket.

Inflatables and big displays

Inflatables have a fan running constantly. One on its own is fine. Six of them, plus a projector, plus a light up reindeer, all on a chain of leads from one socket, is a different story.

For a big display, add up the wattage on each label, spread the load across more than one socket, and talk to an electrician about a second outdoor socket or a dedicated circuit.

Indoor vs outdoor rated lights

• Outdoor rated lights should be marked as suitable for outdoor use. Electrical Safety First suggests looking for the water drop symbol or an IP rating. Personally, I’d look for IP44 or better outside.
• Indoor lights should stay indoors, even on a dry night.

Transformers and plugs

Many LED sets run at extra low voltage (for example 24V) through a transformer. That’s a safer setup outside, but the transformer itself is often not waterproof. Electrical Safety First advises keeping plugs and transformers indoors, even when the lights themselves are outdoor rated. Check the instructions for yours.

Check your old lights before they go up

Lights stored in a loft or damp garage can pick up damage. Look for:

• Cracked or broken bulbs and holders
• Damaged or chewed cables (mice love a Christmas box)
• Loose wires at the plug or transformer
• Water marks or rust inside the controller

If in doubt, bin them. It’s not worth the risk.

Timers and smart plugs outdoors

Timers are brilliant for Christmas lights, but most plug in timers and smart plugs are made for indoor use. If one is going outside, it needs to be outdoor rated. Another option is an indoor switch wired in to control the outdoor socket from inside.

Why does my RCD trip when it rains?

A common call I get in December goes something like: “The lights were fine yesterday, then it rained and now the electrics keep tripping.”

That’s usually the RCD doing its job. Water has got into a connection somewhere, often a plug on an indoor extension lead, a cheap transformer or a damaged light, and current is leaking to earth.

What to do:

• Unplug the outdoor lights and try resetting the RCD
• If it holds, the problem is likely in the lights or leads
• Let everything dry out and check for damage before trying again
• If it keeps tripping with everything unplugged, call an electrician

Please don’t move the lights to a socket without RCD protection to stop the tripping. That removes the safety net when you need it most.

Book early: December gets busy

From late November onwards, our diary fills up fast with jobs people want done before family visits.

If you want an outdoor socket in time for the lights going up, October or early November is the sweet spot. Adding a socket outside is often a fairly quick job when there’s a suitable circuit nearby, though it depends on your property. Some jobs need a new circuit, which is notifiable under Part P of the Building Regulations in England. As a registered electrician, we handle the paperwork for that.

An outdoor socket is useful year round

Customers across Wickersley, Bramley, Maltby and further afield use theirs for:

• Pressure washers and car cleaning
• Garden lighting and water features
• Lawnmowers, hedge trimmers and leaf blowers
• Summer parties and outdoor speakers

For bigger loads, a standard outdoor socket isn’t the right answer. Hot tubs usually need their own dedicated supply, which I cover in our hot tub electrics guide, and charging an electric car properly is best done with a dedicated EV charger installation. If you need power further down the garden, have a look at our guide on garage, shed and outbuilding power.

Christmas lights safety tips

• Use lights marked as suitable for outdoor use outside
• Plug outdoor lights into a 30mA RCD protected socket
• Keep indoor extension leads indoors and don’t daisy chain them
• Check old lights for damage before use
• Keep transformers and plugs dry, or use outdoor rated ones
• Use an outdoor rated timer or smart plug outside
• Switch lights off when you go to bed or go out
• If your RCD keeps tripping, find out why rather than working around it

For more, Electrical Safety First’s Christmas lights advice is well worth a read.

Frequently asked questions

Can I plug Christmas lights into an ordinary outdoor socket?

Yes, as long as the lights are rated for outdoor use and the socket is RCD protected. For lights left plugged in for weeks, a socket with an in use cover keeps the plug protected from rain.

What IP rating should an outdoor socket have?

Around IP66 is common for outdoor sockets, but check whether that rating applies with a plug in or only with the lid shut. An in use cover gives better protection while something is plugged in.

How many Christmas lights can I plug into one socket?

A 13A socket can handle roughly 3kW in total. LED lights use very little, so it’s usually inflatables, projectors and other extras that push you towards the limit.

Do I need an electrician to fit an outdoor socket?

I’d recommend a qualified electrician. If the job needs a new circuit, it’s notifiable work under Part P in England, and a registered electrician can self certify it for you.

When should I book an outdoor socket before Christmas?

October or early November is ideal. December is a busy month for us, and we cover Rotherham, Sheffield, Barnsley and Doncaster, so booking early gives you the best choice of dates.

Related services and guides

• Outdoor socket installation
• Garden lighting
• Outdoor electrical work
• Hot tub electrics: what to sort before it arrives
• Power to your garage, shed or outbuilding

Contact MP Electrical

If you need help with an outdoor socket for your Christmas lights or any electrical work in Rotherham or South Yorkshire, MP Electrical are happy to help.

📞 Call our office on 01709 645115

🌐 Visit: rotherhamelectrician.co.uk

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