Why is my electrical cable getting hot inside the wall?
Quick answer
Hot electrical cables inside walls are most commonly caused by overloaded circuits, undersized cable, or poor connections creating excess resistance. Turn off the affected circuit at the consumer unit immediately and do not use it until inspected. A qualified electrician must investigate — hot cables are a serious fire risk. Never ignore warm or burning smells from walls, as insulation damage or arcing can ignite surrounding materials without warning.
🏠Homeowner view
Why Is My Cable Getting Hot Inside the Wall?
Finding that a cable or the area around a socket or switch feels warm — or smelling something burning from inside a wall — is a warning sign you must take seriously. Cables are designed to carry electricity safely without generating noticeable heat. When they do get hot, something is wrong.
What Causes Cables to Get Hot?
Overloaded circuit — Too many appliances drawing more current than the cable is rated for. The cable heats up just like a wire in an electric fire element.
Undersized cable — If a previous DIY job used cable that is too thin for the load it serves, it will overheat regularly.
Loose or poor connections — A badly terminated connection at a socket, junction box, or consumer unit creates high resistance at that point, generating localised heat.
Cable buried in insulation — Cables concealed in loft insulation or inside insulated walls cannot shed heat properly, reducing their current-carrying capacity significantly.
Damaged or degraded cable — Old rubber-insulated cables (pre-1960s) or cables that have been mechanically damaged can develop faults causing heating.
Sustained high load — Running high-draw appliances (electric showers, ovens, heaters) on circuits not designed for them.
What Should You Do Right Now?
1. Switch off the circuit at your consumer unit (fuse board) immediately.
2. Do not switch it back on until an electrician has inspected it.
3. If you smell burning or see scorch marks, call 999 — there may already be a fire inside the wall cavity.
4. Do not attempt to open the wall yourself unless you are certain the supply is isolated.
When to Call an Electrician
Always call a qualified electrician (Part P registered) for this fault. This is not a job for DIY investigation beyond switching off the supply. An electrician will:
Test insulation resistance on the affected circuit
Check all connections with a thermal imaging camera
Verify cable sizing against the load
Issue an Electrical Installation Condition Report (EICR) if faults are found
This fault carries a real risk of house fire. Do not delay.