What is a split neutral fault and can it really cause a house fire?

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. Warning signs to look for Lights flickering or pulsing rhythmically Lights suddenly becoming much brighter or dimmer than usual Appliances behaving strangely, especially across different rooms at the same time A buzzing or humming sound from the meter area A burning smell near the consumer unit or meter What you should do safely Do not go near the meter or service head. That equipment belongs to your network operator, and the incoming supply is always live even when your main switch is off. If you suspect a split neutral, turn off your main switch at the consumer unit to disconnect your internal circuits, then call a qualified electrician immediately. If you can smell burning or see scorch marks, evacuate the property and call 999 and your network operator's emergency line. In most of England, Scotland, and Wales that is National Grid Electricity Distribution, now trading as National Grid Electricity Networks. The number is 105.