Electrical Safety Advice for USB Chargers

USB chargers usage and safety

A USB charger provides a standardised connector so you can charge your devices on-the-go. But it’s important to use reliable models and ensure they work properly.

A USB charger converts AC power from a wall outlet into the DC power needed to charge portable electronics. Power flows to the device while data can flow in either direction.

USB-A is the older, standard rectangular port.
USB-C is the smaller, reversible, faster, and modern standard used for new smartphones, tablets, and some laptops.

Both usually consist of a wall plug (adapter) and a USB cable that connects to the gadget.

Some chargers include both USB-A and USB-C ports and some enable faster charging through standards like power delivery (PD).

The USB-B connector is still used but is no longer common in modern devices. It’s primarily used for printers, scanners, external hard drives, and studio audio equipment.

Key points

Read the manufacturer's instructions and always follow them.
Protect your USB charger from damage and don’t immerse it in water.
Do regular checks of the charger plug and socket for burn and scorch marks.

Buying a USB charger

Whichever you choose, buy your USB charger from a reputable retailer rather than a third-party seller online, as it may not have passed all the necessary safety checks.
Don’t buy substandard or counterfeit USB chargers from third-party sellers online as they have serious safety concerns and may present a higher risk of exploding or catching fire. They may also damage your device which could void your guarantee.
USB chargers are required to meet the requirements of the Electrical Equipment (Safety) Regulations 2016.
USB chargers operate with a default voltage of 5V, but fast-chargers can negotiate higher voltages through a “digital handshake” to deliver more power safely. This handshake prevents high voltage from damaging non-compatible devices by defaulting to the standard 5V if the communication fails.
Register your USB charger so you can be contacted easily if there is a safety recall of your product. It’s also much easier to return a faulty item or order a repair if it’s registered.

Using a USB charger safely

Use the charger only for its intended use in accordance with the manufacturer’s instructions.
Keep USB chargers away from heat sources and liquids especially direct sunlight, humidity, and water.
Exposing a USB charger to extreme temperatures can be dangerous. For example, don’t leave it in a parked car where it could get cold in winter or hot in summer.
Unplug your device after charging, don’t leave it on prolonged charge when not in use and ensure it is uncovered and in a well-ventilated environment when charging.
Don't use USB chargers overnight or while you are out of the house.
When travelling abroad, check the voltages in the country you are visiting. Most modern chargers can handle a wide range of input voltages but check in case you need to source a different charger.
USB chargers are robust but not indestructible so handle them carefully. And don’t dismantle or attempt to repair faulty chargers.
While charging, if you notice any odd smells or any sparking or smoke, or any swelling, cracks or damage, unplug immediately and contact the retailer and/or manufacturer.
Regularly check the charger and/or plug and your socket-outlet for burn marks, sounds of ‘arcing’ (buzzing or crackling) or if it feels too hot to touch.

ALWAYS

Do plenty of research first before buying.
Buy chargers from a reputable retailer.
Unplug your device after charging, don’t leave it on prolonged charge.

AVOID

Buying substandard or counterfeit chargers as these can be dangerous.
Using USB chargers overnight or while you are out of the house.
Using the USB charger if you notice any damage or sparks.

Stay safe with electrical products

Check plugs and sockets

Don't ignore burn marks, ‘arcing’ (buzzing or crackling) sounds, fuses blowing, circuit-breakers tripping, or if it feels hot to touch.

Unplug and contact the retailer, manufacturer, or a qualified repair technician.

Protect with an RCD

An RCD (residual current device) in your consumer unit (fusebox) protects you from electric shocks if a product is faulty.

If you don’t have RCD protection, use an RCD plug on the socket where the product is plugged in.

Fit smoke and heat alarms

Ensure there is at least one smoke or heat alarm per floor in your property. Fit enough alarms to cover all areas where a fire could start.

Test alarms at least once a month. Replace them every ten years or when the replace by date is reached.

Additional info

Modern USB charging has evolved a lot, and what you get depends on both the charger and the cable you use.

Older USB‑A ports (such as those on PCs and older chargers) provide limited power and were originally designed mainly for data, not fast charging.

Many wall chargers and power banks use a system called USB Battery Charging. This allows devices such as phones and headphones to charge more quickly (typically 7-10 watts) but does not support data transfer.

Even without any advanced features, a USB‑C charger can safely provide more power than older USB connectors, making charging faster and more consistent.

The most powerful and flexible option is USB Power Delivery (USB‑PD) which works over USB‑C, as the charger and device “talk” to each other to agree on the safest and fastest charging level.

This allows small devices such as phones to charge quickly while larger devices such as laptops and monitors can receive much higher power through the same type of cable.

Most modern laptops now charge using USB‑C Power Delivery rather than a proprietary charger, and the latest version can deliver enough power even for demanding devices.

A USB‑C with Power Delivery means fewer chargers, faster charging, and one connector that works across many devices.

USB chargers