What should I do about a burning smell from a socket?

Glossary · Wiring, circuits and faults

What causes it

Heat is the cause. Something in the path of the current is getting hotter than it should, and the plastic around it is starting to cook. Electrical Safety First’s guidance points to a few likely sources. Overloading is the first: plugging in appliances that together exceed the maximum current rating can make the extension lead, the adaptor or the plug in the wall socket overheat and cause a fire.^{[1]Electrical Safety First, Extension leads, cable reels and block adaptors} The charity also warns that running a cable reel while it is still wound can make it overheat.^{[1]Electrical Safety First, Extension leads, cable reels and block adaptors}

A damaged appliance or lead is another source, and so is a socket that is worn or has a poor connection. Only a registered electrician can tell which it is. The smell is the warning, not the diagnosis.

What you can check yourself

Electrical Safety First lists danger signs that householders can look for without touching anything inside the socket.^{[1]Electrical Safety First, Extension leads, cable reels and block adaptors}

The charity also says not to ignore buzzing or crackling sounds, or a plug or socket that feels hot to touch. Its advice is to unplug and contact the retailer, the manufacturer or a qualified repair technician.^{[4]Electrical Safety First, FAQ for Electrical Safety - Your Questions Answered} That is the household action: unplug the appliance. Do not open the socket or the plug, and do not try to repair either.

Check the extension lead too. Most are rated at 13A, but some older ones and many cable reels are rated lower, and the rating should be marked on the lead.^{[3]Electrical Safety First, Electrical Safety Advice for Overloading Sockets} Only one extension lead should go in each socket, and never plug one into another.^{[3]Electrical Safety First, Electrical Safety Advice for Overloading Sockets}

When to call an engineer

If a socket has burn marks or feels hot, get a competent registered electrician to check it.^{[2]Electrical Safety First, Fire prevention tips} Leave the socket out of use until it has been checked, because the fault may be in the socket or the circuit rather than the appliance.

If you regularly rely on extension leads, Electrical Safety First suggests considering additional wall sockets, installed by a registered electrician.^{[1]Electrical Safety First, Extension leads, cable reels and block adaptors} Our general electrical maintenance page covers socket work, and emergency electrician covers urgent call-outs. See also overload for why too many appliances on one socket is a problem.

Electrical Safety First also recommends a working smoke alarm on each floor, and says to check its expiry date because the sensors deteriorate over time.^{[2]Electrical Safety First, Fire prevention tips}

Example

Callum notices a smell of hot plastic in his Chapel Allerton kitchen and finds the plug of a heater scorched where it meets the wall socket. He unplugs the heater, leaves it out of use and books an electrician to inspect the socket. The heater had been running from a four-way adaptor shared with a kettle and a toaster, the sort of combined load the charity warns against.

What people get wrong

People often treat a faint burning smell as the appliance’s problem and carry on using the same socket. Electrical Safety First lists it as a danger sign for the socket as well as the appliance, and says to get a registered electrician to check any socket with burn marks or one that feels hot.

The other mistake is to try a cosmetic fix, such as a new plug or a new adaptor, without finding out why the heat built up in the first place.

The bottom line

A burning smell near a socket is a danger sign, not a nuisance. Unplug the appliance, stop using the socket and contact a registered electrician to inspect it. Do not open the socket or repair it yourself. Fit working smoke alarms and keep extension leads within their ratings so that a hot spot is less likely to start.