What causes a split neutral fault and why is it dangerous – Advice from Electriman, North London Electricians

What Is a Split Neutral Fault?

A split neutral fault happens when the neutral wire in your electrical circuit breaks or becomes disconnected, while the live wire stays connected and energised. In a healthy circuit, current flows out through the live wire and returns safely through the neutral. When the neutral is broken, that return path is lost — and electricity can behave in very unexpected and dangerous ways.

Why Is It So Dangerous?

Unlike a blown fuse or tripped breaker, a split neutral doesn't always cut the power. Instead, it can:

Make metal casing on appliances become live at mains voltage (230V)

Cause lights to flicker, dim, or burn extremely bright as voltage shifts unpredictably

Allow current to return through earth conductors or pipework, creating hidden shock and fire risks

Fool you into thinking a circuit is safe when it isn't

Common Causes

Loose or corroded neutral terminal at the consumer unit, junction box, or socket

Rodent damage to cable insulation and conductors in roof spaces or underfloor areas

Old wiring with aluminium neutrals that have corroded at terminations

Poor workmanship — an undertightened screw terminal that has gradually worked loose

Mechanical damage to cables during building works or DIY

What You Might Notice

Lights flickering or changing brightness for no obvious reason

Appliances behaving erratically or failing

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.