What is this?
An electrical arcing or crackling sound is the noise made when electricity jumps across a gap between two conductors. It sounds like a sharp crackling, snapping, or zapping — similar to static electricity but louder and more sustained. Arcing occurs where connections are loose, contacts are worn, or insulation has broken down. It is distinct from a hum or buzz and indicates a more active and dangerous fault.
Common causes
- Loose connection at a socket, switch, or junction box creating intermittent arcing
- Worn switch contacts arcing when operated or under load
- Damaged cable insulation allowing conductors to arc through the gap
- Carbon tracking on the surface of a socket or switch (conductive path formed by previous arcing)
- Failing MCB or RCD arcing internally
- Water or moisture creating a conductive path between live parts
Is it dangerous?
Yes, very dangerous. Electrical arcing generates temperatures of 3,000 to 20,000 degrees Celsius. At these temperatures, surrounding materials — timber, insulation, plasterboard, plastic — can easily ignite. Arc faults are particularly dangerous because they can occur inside walls, behind sockets, and in ceiling voids where they cannot be seen. If you hear crackling from your electrics, take it seriously and act quickly.
Can I fix it myself?
No. Try to identify where the sound is coming from. If it is a specific socket, switch, or fitting, stop using it. If the sound comes from the consumer unit, do not touch it — turn off the main switch if you can safely do so. If the sound is in a wall, turn off the circuit serving that area. Call an electrician promptly.
When to call an electrician
Call an electrician the same day. If the arcing is continuous, loud, or accompanied by burning smell, smoke, or visible sparks, treat it as an emergency. An arc fault can transition to a fire within minutes if the conditions are right. Do not wait to see if it stops on its own.
What will an electrician do?
Systematically locate the source of the arcing using testing and inspection
Use thermal imaging to identify hotspots if the sound is coming from within a wall
Isolate the affected circuit and dismantle the faulty fitting or connection
Repair or replace the connection, fitting, or cable section where arcing is occurring
Test the circuit for insulation integrity after the repair
Advise on the installation of an AFDD (Arc Fault Detection Device) for ongoing protection
Typical cost
£100 – £350
Costs depend on how long it takes to locate the fault and the extent of repair needed. Concealed faults (behind walls) are more expensive to access. AFDD installation is an additional cost if recommended.
