US vs UK Plugs and Voltage: Using International Electricals Safely

Plenty of useful gadgets are designed for the US market, and many of them work perfectly well in the UK. Others can overheat, fail or become a fire risk if they are plugged in the wrong way. The difference comes down to two things: the voltage the device is built for, and how it connects to a UK socket. This guide explains how to read a rating label, when a simple plug adapter is fine, when it is not, and why the fuse in a UK plug matters.

230V vs 120V: why it matters

According to Electrical Safety First, the UK supply is 230V at 50Hz and uses Type G plugs with three rectangular pins and a built-in fuse. The US supply is 120V at 60Hz, with two flat-pin Type A plugs or Type B plugs that add a round earth pin.

A device built only for 120V receives roughly twice its design voltage if it is plugged into a UK socket. Electrical Safety First warns that it can be extremely dangerous to use an appliance rated at a voltage different from the supply. The frequency difference matters too: an appliance may work, but not properly, on the wrong frequency.

How to read the rating label

Every mains-powered product should have a rating plate or printed label, either on the device itself or on its power brick. Look for the word INPUT:

• INPUT: 100–240V ~ 50/60Hz means the product is dual-voltage (sometimes called universal input). It is designed to work on both US and UK supplies.
• INPUT: 230V or 220–240V means it is built for UK and European supplies.
• INPUT: 110V, 120V or 110–120V only means it is not suitable for a UK socket as it stands.

Phone chargers and laptop power supplies are commonly dual-voltage, but always check your own label rather than assuming. If the label is missing or unreadable, do not plug it in.

Plug adapters vs voltage converters

A plug adapter changes the shape, not the power

A travel adapter only lets a foreign plug fit into a socket. Electrical Safety First is clear that it does not convert the voltage or frequency. That makes an adapter suitable only for dual-voltage (100–240V) devices. Electrical Safety First also advises that travel adaptors should meet BS 8546, should not be used beyond their maximum amp or watt rating, and that some are not suitable for appliances that need an earth connection.

A voltage converter or transformer changes the voltage

For a 120V-only appliance, you would need a step-down converter or transformer rated above the appliance's wattage. Even then, Electrical Safety First's advice on adapting appliances for UK use notes that electronic appliances such as games consoles, TVs, radios and computers aren't suitable for use with converters, and that importing foreign appliances for UK use is not recommended unless the plugs are converted. High-power items that heat, such as hairdryers, kettles and irons, need very large converters. For those, a 230V or dual-voltage version is the safer and simpler choice.

Never use a simple plug adapter with a 110–120V-only appliance.

BS 1363 plugs and fuses explained

UK plugs and sockets are covered by British Standard BS 1363, and the fuse inside the plug by BS 1362. Electrical Safety First's plugs and fuses guidance explains that the fuse protects the cable from overheating, and that manufacturers have standardised plug fuses at either 3A or 13A:

• 3A (red): appliances up to about 700 watts, such as lamps, televisions and computers.
• 13A (brown): appliances from about 700 to 3,000 watts, such as kettles, toasters, microwaves, vacuum cleaners and irons.

If a fuse blows, find out why before replacing it, and only replace it with one of the same rating. The same guidance says appliances should come with either a standard UK plug or a conversion plug (not a travel adaptor) unless they are designed to be hard-wired. A conversion plug fits over the foreign plug, contains a fuse and is designed to stay on the appliance.

What's safe and what isn't

Generally fine

• A dual-voltage device (100–240V) supplied with a UK plug or a fused conversion plug.
• USB-powered gadgets charged from a UK wall charger or a laptop.
• Battery-powered items, charged with a UK-suitable charger.

Take care or avoid

• Any 110–120V-only appliance plugged into a UK socket, with or without an adapter.
• Stacking adapters, or running heaters and kettles through travel adapters or extension leads beyond their rating.
• Chargers or plugs that feel hot, buzz or crackle, or show scorch marks.
• Products with no rating label, no manufacturer name or no safety marking.

GOV.UK's online shopping safety guidance suggests looking for recognised safety markings such as UKCA or CE, clear instructions and safety warnings, and UK contact details for the seller. It also advises reading detailed reviews that mention quality or safety.

Shopping for chargers and adapters

If a product you buy from us is an international version, check the listing and label for 100–240V (or 230V) and a UK plug before you use it. Our chargers and power adapters and wall chargers ranges include UK-plug options. We also stock travel adapters and a small number of voltage converters; always check the converter's wattage rating against your appliance. For desks and entertainment set-ups, see power strips and surge protectors. If you are choosing kitchen gadgets, our countertop ice maker guide includes what to check on a mains appliance.

Summary checklist

• Find the INPUT line on the device or its power brick.
• 100–240V: fine in the UK with a UK plug, a fused conversion plug or a BS 8546 travel adapter within its rating.
• 110–120V only: do not plug in with an adapter. Choose a 230V or dual-voltage alternative instead.
• Check UK plugs carry BS 1363 and fuses carry BS 1362, with the right fuse rating (3A or 13A).
• Stop using anything that gets hot, smells of burning or crackles, and contact the seller.
• If in doubt, ask a qualified electrician before plugging in.

Frequently asked questions

Can I use a US appliance in the UK with just a plug adapter?

Only if its label says it is dual-voltage, such as INPUT 100–240V. A plug adapter does not change the voltage, so never use one with a 110–120V-only appliance.

What voltage does the UK use?

The UK supply is 230V at 50Hz, according to Electrical Safety First. The US supply is 120V at 60Hz.

What is the difference between a travel adapter and a conversion plug?

A travel adapter lets a foreign plug fit a socket temporarily. A conversion plug is fused and designed to stay fitted to the appliance, and Electrical Safety First says appliances should come with a UK plug or a conversion plug, not a travel adaptor.

Which fuse should be in my plug?

Electrical Safety First says plug fuses are standardised at 3A for appliances up to about 700 watts and 13A for about 700 to 3,000 watts. Always replace a fuse with one of the same rating.

Is it safe to use a voltage converter with a TV or computer?

Electrical Safety First advises that electronic appliances such as games consoles, TVs, radios and computers are not suitable for use with converters. Choose a dual-voltage or 230V model instead.