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This page describes how you can use 120V rated US devices in the UK, where the mains is 240V.

Summary

People moving from US or Canada to the UK or Europe sometimes bring portable appliances with them which they would like to use in their new country of residence. Some devices are universal but this is very often not the case and you may need a transformer that could cost more than the device is worth. This page should enable you to determine what you need, if anything.

Safety

Simply plugging a North American device into a European mains socket, perhaps via a simple adapter may well destroy the device and may create a fire hazard.

Mains supply standards

The "electrical pressure" is measured in Volts. In North and Central America the mains supply is between 100 and 127V (120V in the US and Canada) whereas in the UK, Europe and many othe parts of the workd, it's between 220 and 240V (230V in Europe and 240V in the UK).

There are also 2 different standards for mains frequency (50 or 60HZ) but this is practically never of any consequence and so can be ignored. However, a North American clock using the mains fequency for its time standard would loose 10 minutes every hour. Anything containing a fan, the fan will run about 17% slower.

Checking the Ratings

First of all, you need to look at the ratings plate of the device, usually on the back or underneath. There are 2 key ratings to look at:

• The voltage, which we've already discussed, and
• The wattage. This is the amount of power the device takes, and it'll be written as something like 40W, or 750W (or any other number of watts).

Universal devices

Some devices (in particular TVs, audio equipment and mains chargers and adapters) may be universal, having a voltage rating spanning both standards (e.g 100-240V). In order to use such a device, all you need do is to change the plug, or use a simple adapter. For a laptop adapter marked as universal you can just swap the detachable mains lead for a UK or European one. Search online for "3 pin cloverleaf cable" and select one with a UK or your national type of mains plug.

Some other devices such as older HiFis may have a switch near the mains inlet, allowing them to be used on the other mains standard. You will probably need a screwdriver to change it. You will then just need to change the plug, or possibly use an adapter or replace the detachable mais lead, if it has one.

If you need a transformer

In this case you need a transformer to convert 240V to 110V, rated for the number of watts of your device. (Note that a transformer may be rated in VA, not Watts. The difference is technical and needn't concern you.) For anything rated much over 100W the transformer will probably cost more than the device is worth, but for small audio/visual equipment, hair straighteners (but not hair dryers), lamps etc something like this should do (though I don't see a CE mark - slightly concerning): https://www.ebay.co.uk/itm/313914115501?hash=item4916bd45ad:g:BPYAAOSwhDBiMAz2 A builder's transformer such as this will drive higher power devices (with an adapter on the output), but not cheap!: https://www.screwfix.com/.../carroll-meynell-3000va.../84144