Why does my neutral wire at the fuse box glow red when nothing is switched on – Advice from Electriman, North London Electricians

Finding a glowing red neutral wire in your fuse box is genuinely alarming, and your concern is completely justified. That red glow is heat, and heat in electrical wiring is one of the leading causes of house fires in the UK. Here is what is most likely happening and what you should do.

What the neutral wire normally does

In a standard UK single-phase supply, the neutral wire completes the circuit back to the transformer on the street. Under normal conditions it should carry roughly the same current as the live wire, and it should stay cool. If it is glowing red, it is getting far too hot.

The most common reasons this happens

1. Loose or corroded connection at the neutral bar inside the consumer unit. A poor connection creates resistance, and resistance turns electrical energy into heat. Even small amounts of current can cause serious overheating at a bad joint.

2. Overloaded neutral conductor. If multiple circuits share a neutral, an imbalance can cause the neutral to carry more current than it was designed for.

3. Lost or broken neutral on the incoming supply. If the neutral from the street is faulty, strange voltages can appear across your wiring and some conductors can overheat unexpectedly.

4. Damaged or undersized cable. If a previous repair used the wrong cable size, the conductor may not be rated for the current it is carrying.

What you should do right now

Switch off the main switch on your consumer unit. This is

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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.