Arcing inside a wall socket is most commonly caused by a loose terminal connection, where poor contact causes electrical current to jump across a gap, generating heat, light, and a crackling sound. Turn off the circuit at the consumer unit immediately and do not use the socket. This is a serious fire and electric shock hazard. Do not investigate inside the socket yourself — contact a Part P registered electrician as soon as possible.
🏠Homeowner view
What Does Arcing Inside a Socket Mean?
If you have seen a flash of light, heard a crackling or buzzing sound, or noticed a burning smell coming from behind your socket faceplate, your socket is arcing internally. This means electrical current is jumping across a gap rather than flowing safely through a complete circuit — similar to a tiny lightning bolt happening inside your wall.
This is a serious electrical fault and a potential fire hazard. Stop using the socket immediately.
Most Common Causes
Loose terminal screws — the most frequent cause; wires work loose over time due to thermal expansion and contraction
Damaged or frayed cable insulation — the plastic sleeve protecting the wire has worn away, allowing current to jump
Overloaded socket — drawing more current than the wiring can safely handle causes heat and eventual arcing
Old or worn socket — sockets degrade over years of use, and internal contacts can corrode or weaken
Water ingress — moisture behind the socket can cause tracking and arcing between terminals
Poor original installation — cables not properly stripped or clamped at the time of fitting
What You Can Safely Do Right Now
Switch off the circuit at your consumer unit (fuse box) — look for the circuit breaker labelled 'sockets' or 'ring main'
If you are unsure which circuit it is, switch off the main switch entirely
Do not remove the faceplate yourself — behind it may be live conductors, damaged insulation, or even scorch damage
Check whether the socket feels warm or hot to the touch from the outside — if so, treat it as urgent
Note whether the RCD or breaker has tripped — this is useful information for your electrician
When to Call an Electrician
You should call a Part P registered electrician in all of the following situations:
You have seen or heard arcing of any kind
The socket is warm, discoloured, or smells of burning
The circuit breaker keeps tripping
Your installation is more than 25 years old
Arcing that goes untreated is one of the leading causes of house fires in the UK. This is not a fault to monitor or delay acting on.