Why is my old rewireable fuse box beginning to smoke at the main terminals – Advice from Electriman, North London Electricians

If you can see or smell smoke coming from the main terminals of your old rewireable fuse box, this is a genuine emergency and should not be treated as a minor inconvenience. The situation needs to be taken seriously right away.

What is actually happening inside the board

Your rewireable fuse box was almost certainly installed several decades ago, likely in the 1960s, 1970s or 1980s. Over that length of time, the main incoming terminals where the electricity supply connects to the board can become loose, corroded or degraded. When a terminal is not making a solid, clean electrical contact, resistance builds up at that joint. Resistance turns electrical energy into heat, and if enough heat builds up, it can scorch the surrounding plastic, melt insulation on cables and ultimately start a fire inside the board itself.

The smoke you are seeing is often burning plastic or insulated cable sheathing. In some cases it is the Bakelite or early thermoplastic casing of the fuseboard itself beginning to char.

What you should do right now

Do not touch the terminals or the wiring. These are live parts and are extremely dangerous.

If it is safe to reach the main switch on the board, switch it off. This is usually a large lever or rotary switch at the top or side of the unit.

If there is any sign of flames, leave the property immediately and call 999.

Do not restore power until a qualified electrician has inspected the board.

Call a P

Need a qualified electrician in North London?

Electriman covers Mill Hill, Barnet, Finchley, Edgware, Enfield, Watford and surrounding areas. All work is Part P certified and fully insured.