Shower tripping the fuse box?

1. A failing heating element — the usual suspect

The element inside the shower's tank heats mains-pressure water on demand, and years of thermal shock plus Fylde Coast limescale eventually crack its outer sheath. Water then reaches the live element wire, current leaks to earth, and the RCD does exactly what it's there for. The tell-tale pattern: the trip happens seconds after the water starts flowing, gets more frequent over weeks, and often follows a spell of lukewarm showers. Elements are rarely economic to replace on their own — a new shower unit is usually the answer.

2. Water getting inside the unit

A perished hose seal, a cracked casing or a weeping inlet connection lets water dribble onto the terminals inside. This one is worth taking seriously: water on live parts can escalate beyond nuisance tripping. If you can see drips from the casing, or scale streaks below it, stop using the shower and leave its pull-cord off until it's inspected.

3. An undersized cable or breaker after a kW upgrade

Showers grew: plenty of 1990s bathrooms have a 7.2kW cable feeding a 9.5kW shower someone fitted "like for like". The overloaded cable warms up and the breaker trips mid-shower — typically minutes in rather than seconds, and worse in summer when incoming voltage runs higher. The fix is a properly sized circuit, not a bigger breaker on the old cable, which just moves the heat into the wall.

4. A worn pull-cord switch

The ceiling switch carries the shower's full load every time it clicks. After years of steamy bathrooms the contacts pit and arc — listen for buzzing, look for a browned or crackling switch, sniff for that hot-plastic smell. A pitted switch can trip the circuit and is a small, cheap replacement caught early.

5. RCD nuisance tripping

Sometimes the shower is innocent. An ageing RCD, or the combined leakage of everything else sharing it, can sit just below the trip threshold until the shower's small extra leakage tips it over. Clue: the RCD also trips occasionally without the shower running. We test the RCD and measure leakage across the board rather than condemning the shower on sight.

6. Loose connections heating up

A 40-amp load punishes any terminal that isn't tight. Loose connections at the shower, the pull-cord or the consumer unit heat up, char and eventually trip the breaker — and they're a fire risk in their own right. This is a screwdriver-and-thermal-check job for us, not for a Sunday afternoon.

What you can safely check yourself

• Which device trips — a single MCB, or the RCD covering several circuits.
• The timing — instant, seconds after water flows, or minutes into a shower.
• Whether the pull-cord buzzes, smells hot or looks discoloured.
• Any visible drips or scale trails on the shower casing.

That's the limit. Everything past the faceplate involves a 40-amp circuit and water in the same box, so leave the screwdriver in the drawer. Note what you observed — it genuinely shortens our diagnosis.

Can't I just keep resetting it?

Tempting, and we understand why people do — but no. Each reset pushes full power back into whatever is failing. A leaking element degrades further with every heat cycle, a loose connection chars a little more, and water sitting on terminals gets another chance to do real damage. There's also a warning in the pattern itself: a trip that used to happen once a month and now happens every shower is a fault accelerating, not a moody RCD. Leave the shower's pull-cord off, use the bath or another shower, and get it looked at — the diagnosis costs less than the consequences.

What fixing it costs

Fault-finding runs at around £60 for the first hour, and the six causes above are usually identified within it — details on our fault-finding page. If the unit itself has failed, a like-for-like shower replacement starts from £220 and is typically done in a morning; see electric shower installation prices. Upgrading to a higher-kW shower with a new circuit costs more — we'll quote it straight after testing what your existing cable can carry.