Why is my neutral conductor at the fuse box showing a temperature of 80°C – Advice from Electriman, North London Electricians

Finding that the neutral conductor at your consumer unit (fuse box) is running at 80°C is genuinely concerning and needs prompt attention. To put it simply, 80°C is above the maximum safe working temperature for the standard PVC-insulated cables used in most UK homes, which are only rated to 70°C. Sustained heat at this level can damage insulation, cause arcing, and in the worst cases start a fire inside the consumer unit.

What is a neutral conductor?

The neutral is one of the three wires in your home's wiring — alongside the live and earth. It completes the electrical circuit by carrying current back to the supply. Inside your consumer unit, all the neutral wires from your circuits connect together at a neutral bar or terminal block.

Why does it overheat?

The most common reason is a loose connection. When a terminal is not tight enough, current has to push through a small gap or corroded surface, and that resistance generates heat — exactly like a weak link in a chain getting hot under pressure. Other reasons include:

1. Corroded or oxidised terminals that increase electrical resistance

2. An overloaded circuit drawing more current than the cable is rated for

3. Undersized cable installed at some point that cannot handle the load

4. Multiple neutral wires incorrectly shared or doubled up under one terminal

5. Damaged or degraded insulation from a previous heat event

What should you do right now?

Do not open the consumer u

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