Neutral vs earth
The neutral carries return current; earth is for safety. Confusing them causes real, dangerous faults.
The difference
The neutral is a current-carrying conductor — it's the normal return path for current in a circuit. The earth is a safety conductor that carries current only under fault conditions. They do different jobs and must not be mixed up.
Why it matters
A lost or high-resistance neutral causes strange, dangerous symptoms: single-phase loads see voltages swing high and low as the load changes, damaging equipment. A neutral-earth fault (neutral touching earth) trips RCDs. A 'borrowed' or shared neutral between circuits behaves unpredictably and can leave a circuit live when it should be dead.
Because the neutral carries current, treat it with the same respect as the active — a disconnected neutral on a live circuit can be at a dangerous voltage.
On site
Tell-tale high/low voltages across different loads point to a lost neutral. RCD trips that won't clear can be a neutral-earth fault. Keep neutrals correctly grouped per circuit and never borrow one.
Safety first
A neutral can be at a dangerous voltage — never assume it's safe to disconnect on a live circuit. A lost neutral can damage equipment and shock; treat as urgent.
Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.
Related faults
Lost or high-resistance neutral
Strange symptoms across a circuit or installation — voltages going high and low on different loads, flickering, equipment damage — pointing to a lost or high-resistance neutral.
RCD won't reset at all
The RCD won't stay reset — the toggle won't latch up, or it trips instantly every time, so the circuit can't be restored.
Lights flickering
One or more lights flicker — constantly, intermittently, or when other appliances run. Common with LEDs and dimmers, but can also signal a loose connection.
Related definitions
Earthing & bonding
Connecting exposed metal to earth so a fault blows protection fast and metalwork can't become live.
RCD (safety switch)
Detects earth leakage and disconnects fast to protect people from electric shock.
Three-phase power
Three AC supplies offset in time, giving smooth power and a rotating field for motors.