What is a split neutral fault and can it really cause a house fire – Advice from Electriman, North London Electricians

A split neutral fault is one of the most dangerous electrical faults a home can develop, yet most homeowners have never heard of it. Here is what you need to know in plain English.

What the neutral actually does

Every circuit in your home has three wires: live, neutral, and earth. The neutral wire completes the circuit and returns current safely back to the supply. Under normal conditions it sits very close to 0 volts. Your home runs on a single-phase 230-volt supply, and the neutral is what keeps that voltage stable.

What goes wrong with a split neutral

If the neutral conductor breaks, corrodes, or works loose anywhere between the electricity supplier's equipment and your consumer unit, the reference point that holds your voltage at 230 volts disappears. If any electrical load is connected at the time, the voltages across your circuits can shift dramatically. Some circuits may see voltages well above 230 volts, while others drop far below. This is sometimes called a lost neutral or open neutral.

Why it is a fire risk

An appliance designed for 230 volts that suddenly receives 300 volts or more will overheat rapidly. Motors can burn out. LED drivers can fail dangerously. Wiring insulation can melt. All of this can happen within seconds, and without a protective device tripping, because the overcurrent protection does not necessarily see anything unusual — it is the voltage that is the problem, not always the current.

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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.