Extension sockets and adapters

There are several safety related issues concerning plugging appliances either into double adapters, modern multiple extension sockets, or long extension leads. There are multi socket extension cables with room for up to 6 different appliances so it’s very easy to overload.

As long as their combined usage doesn’t exceed 13 Amps you can safely plug in and use up to 6 electrical products. However, it is very easy to overload these devices and many people don’t realise how easy. Overheating and eventually a risk of fire can be caused by as few as just 2 appliances if they use a lot of electricity – eg. washing machine and a kettle.


Using appliances with plug adaptors or multiple socket extension cables

A radio, phone charger, two lamps and a wireless router for example would potentially only add up to less than 3 amps. But you can dangerously overload an extension with just a washing machine and a microwave.

Washing machines, tumble dryers and dishwashers all use so much electricity that they should never be used together on the same wall socket. They usually use between 10 and 13 amps.

Extension cables with just one socket at the end

An extension cable with just one socket is preferable to a multi socket one. But it’s not ideal to plug a washing machine, dryer or dishwasher permanently into any extension cable because it introduces an extra risk of electrical overheating as well as extra potential bad connections.

Miele for example say in their washing machine instruction book –

Do not connect via an extension lead. Extension leads do not guarantee the required safety of the appliance (e.g. danger of overheating)  ”


Many white goods appliances are plugged into extension cables. Anyone deciding to do so should at least use the right type of extension cable. You cannot use a 2 core extension cable which has no earth. If you do, although your machine will work, it is in a potentially lethal condition because it isn’t earthed – see I get electric shocks from the machine.

You must also ensure the cable is rated for 13 Amps. Many extensions have thinner cable than that of the washing machine.

This is an indication that the cable is meant for lawn mowers, lamps etc and not large white goods. If the cable is just as thick or thicker than that of your appliance then it should be 13 Amp and 3 core (with an earth lead).

Don’t assume anything though, check. Using a 5 or 10 Amp rated cable can cause overheating and is dangerous. Using cable that has no earth can kill if your appliance develops an insulation fault.


Wind up extension cables

Finally, note that extension cables that wind up must be fully unwound when in use. This type of extension cable will have two ratings written on it in amps. You will see that when wound up, or not fully unwound, the unit cannot take as many amps as when it is fully unwound.

For washing machines, dishwashers and tumble dryers (that can draw close to 11 amps) they need to be fully unwound or they can get hot and overheat. In fact many of these wind up extension reels are only rated for 10 Amps so avoid.


Try to avoid extensions and adaptors

There is a dilemma regarding extension leads and adaptors. Firstly, they exist, and are sold in their millions. Therefore they must be safe. Yet it’s likely that any appliance user manual will advise that they are not to be used. This is a puzzling contradiction. If they are dangerous, they couldn’t be legally sold in the UK.

However, manufacturers know that an extension lead is a third party component added to their appliance which can develop faults which they have no control over. Many extension sockets are very cheap, and don’t seem to be made of high quality materials. Some extension cables can also be very long. Extending the length of an appliances mains cable is not ideal.

Neither is adding extra electrical connections between the appliance plug and the wall socket. Here is what my Miele tumble dryer user manual says on the subject –

Do not connect the appliance by an extension lead, multi socket adaptor or similar. These can overheat and are a fire hazard  ”


So there we have it. However, as I said, if they are genuinely a fire hazard – how come they are happily sold in their millions – and in virtually every house in the country? The truth is they are an extra potential for something to overheat in high current appliances. If you can, always plug a washing machine, dishwasher, tumble dryer (or any appliance with a heating element inside) directly into a wall socket.

If this is impossible, and you have to use an adaptor or extension cable then use a good quality one. Use one as short as possible. Regularly check the plug where it plugs into the wall socket. Regularly check the individual sockets on the extension lead as well as the appliance’s plug. Look out for discolouring where it’s might be overheating and melting the plastic. Do not ignore anything like that.


Strange fishy smell near washing machine or when appliance is running?

Beware of a strange fishy smell coming from the kitchen or laundry room (unless you have some real fish in there of course).

We experienced such a puzzling smell for several days in our kitchen before I eventually tracked it down to electrical overheating in a plastic 13 amp plug.

A bad connection was causing sparking and burning and the plastic gave off this weird smell. I’m currently getting exactly the same smell when I turn a light on in a room at the back of my garage and I know it’s caused by melting plastic used in plugs, sockets, adaptors and light fittings.

If you get such a strange fishy smell near any of your appliances check the plugs and sockets for dangerous overheating.

Check if you are overloading a socket with this tool

The overload Socket Calculator is brought to you by Electrical Safety First.

How to work out how many amps your appliances use

If the Electrical Safety First tool above doesn’t help, or you want to make more accurate calculations you can work it out for yourself. It’s easy enough. You need to work out how many amps each appliance uses and make sure the combined total does not exceed 13 amps.


The amps an appliance uses can be worked out by dividing the wattage by the voltage (Amps = watts divided by voltage). In the UK the voltage is officially 230 volts (but in practice can be up to 240 volts). So a 1000 watt appliance divided by 240 (volts) is 4.16 amps. Do not go on what fuse the appliance takes, that is not how many amps it uses.

rating plate Electrical appliances have a rating plate showing how many watts it uses (see list below for help finding it). The photo above shows the rating plate of my toaster. It says it uses 780 – 930W. It’s unusual to show a range, but clearly we need to use the highest so we start with 930W (Watts). If we divide 930 by 240 (volts) we get 3.875. So the toaster uses 3.87 Amps.

My dishwasher’s rating plate (on the inside of the door) says it uses 1930W. So 1930 divided by 240 is 8.04. The dishwasher uses 8.04 Amps. The toaster and dishwasher running from the same socket would use 11.91 Amps. This is below the 13 Amp maximum.

Help finding appliance rating plates

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72 thoughts on “Extension sockets and adapters”

  1. Hi there I have a query regarding washing machine. If I wanted to move it other side of kitchen, does it need a new power point. Can I spur off a existing 6mm twin earth cable from a cooker switch? Or plug the washer into a standard double socket on other end of kitchen? Any advice I would appreciate it thanks.

  2. Hello, my expertise doesn’t extend too far into electrician territory regarding taking spurs off existing sockets. But any standard socket can accept any appliance apart from a cooker which needs special sockets. So ideally a washing machine should be plugged directly into the nearest wall socket. If there isn’t one close enough it is possible to use a good quality extension cable as long as it isn’t too long. It’s not ideal but extension cables are designed to extend the reach of a wall socket and you should be to plug any appliance in as long as you don’t overload it.

  3. Hi is it safe to plug 2 extension leads into a double wall socket ( so one extension per socket ) thanks

  4. Hello Cal. I’m not an electrician, but my understanding is that a double wall socket is designed to supply a maximum of 13 Amps. Therefore if you connected extension leads into each one you should be able to plug in multiple things as long as they didn’t exceed 13 Amps combined. It’s a good idea to keep products plugged in to a minimum but 4 low power items plugged in to an extension lead can draw half the power of 1 tumble dryer for instance so it’s more about the amount of power being drawn than the amount of appliances. Have a play with the extension overloading tool at the bottom of my article.

  5. brill site,from experience and eltro sensitive person,dont play with electic,my freind a farmer said les my shed give sparking when change swithes,ie on off and other switches, i felt around the use box 6 inches away, i could feel the electric, waiting to short out to earth of a person/animal, i used my electric mains test and showed him,7 inches away from the meter the air was live the tester lit before contact, i went the following day with rubber mat ,wooden brush with bristle,swept all the cobwebs away and cleaned the fuse box,all while off? after this it was safe,but if you dont know about electric ,stay away, in uk its av killer?usa and europe 110 volt, not too bad

  6. Been reading some of the posts and though some information i was already aware of others i was not. Which has prompted me to ask the following 2 questions.

    Question 1. When totting up the amps, reading some posts, people think that we add the amp of the fuse in the plug together to get the total, I am assuming this is incorrect as you would only get 4 X 3 amp plugs in a 4-way extension lead. My way of thinking was each product should have an amp rating, ie 2400 watts for a toaster would equal 10 amps, 100 watt dvd player would equal 0.42 amps, would i be correct in that assumption.

    Question 2. If i am correct about the watts ( Wattage of product divided by 240 Voltage = Amps) then should I be o.k for the following,
    Single wall socket, 12-way extension lead (Tower), each level of 3 sockets has an on/off switch, for products not used all the time.
    Television, Skybox, BT Vision Box, DVD Recorder, Playstation 3, 5.1 Amplifier, Aerial Signal Booster, Lamp, Fan, Laptop, Phone Charger.
    Not all products are on at the same time you will be glad to know, and this is not how they are connected now.
    Apologies for the tong post, but there does not seem to be much information out there regarding safety of extension leads with 10 or more sockets.

  7. Hello Ian. Yes, the fuse amp rating is the ampage that the fuse wil blow at, which is often very different to the amp rating of the appliance. If an appliance doesn’t have it’s amp rating on the rating plate the ampage can be worked out from the wattage and voltage – Amps = watts divided by voltage. In the UK the voltage is (officially 230v but in practice 240 v) so a 1000 watt appliance divided by 240 is 4.16 amps so a 5 amp fuse would be required.

  8. Hi there i want to have a dishwasher and a washing machine. But i only have one wall socket.

    If i get a 13amp extension lead but only ever used one at a time never at the same time would this be safe?

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