Electric shower keeps tripping the fuse box

Electric showers heat water as it flows, which means they draw a lot of current for as long as they run. That makes them one of the hardest working circuits in any home. When a shower starts tripping the electrics, it is worth taking seriously, because the fault is in the one room where water and electricity are closest together.

Which switch is tripping?

Look at the front of your consumer unit after it trips.

Switch	What it suggests
RCD, or an RCBO marked for the shower	Current is leaking to earth, often from the heating element or water inside the unit
MCB for the shower circuit	Too much current, from an overload or a short
Main switch or whole board	A serious fault, or the board is overloaded
Shower stops but nothing in the board has tripped	The shower’s own thermal cutout has operated, or the isolator switch has failed

Many electric showers also have a built in safety cutout that stops the heater if it overheats. That is different from the consumer unit tripping, and often means low water pressure or a scaled up unit.

The common causes

A failing heating element. Over time, the element inside the shower can crack or corrode. Water reaches the live parts and current leaks to earth. The RCD trips, often a few seconds or minutes after the shower starts. This is one of the most common causes, and the fix is usually a new element or a new shower.

Burnt terminals. Showers draw high current. A connection that is slightly loose, at the shower, the isolator switch or the consumer unit, heats up every time the shower runs. Eventually it burns. Signs include brown marks on the pull cord switch, a hot smell, or the shower cutting out.

Water inside the unit. A cracked case, a failed seal or a leak from the shower hose can let water inside. Steam can also find its way in through gaps.

Cable too small for the shower. Showers have got more powerful over the years. If someone fitted a bigger shower on the cable from the old one, the circuit may not be able to carry the current safely. The breaker may trip, or worse, the cable may overheat without tripping.

A tired RCD. Less often, the RCD itself has become oversensitive. An electrician can test it.

What you can do safely

• Stop using the shower until it is checked.
• Switch it off at the consumer unit, not just at the pull cord.
• Look at the pull cord switch from below for browning or melted plastic. Do not open it.
• Check for leaks around the shower unit and hose.
• Note when it trips, straight away, after a few minutes, or only on the hottest setting.

Do not take the cover off the shower or the isolator. Do not swap a breaker for a bigger one. If you smell burning, switch off at the main switch if safe and call for help.

Enfield terraces and their showers

Enfield has the highest share of terraced homes of the boroughs we cover. Figures from the VOA council tax stock of properties show 37.3% of homes in Enfield are terraced houses, with 23.3% built before 1919 and 35.2% between 1919 and 1939.

In Edmonton, Bush Hill Park, Palmers Green and Winchmore Hill, many terraces have had bathrooms fitted into a former bedroom or a rear extension. Electric showers were a popular choice because they work without a hot water cylinder. Over the years, showers in these homes have often been upgraded more than once. Each upgrade is a chance for a bigger unit to be put on cable that was sized for a smaller one.

We also see showers fed from older consumer units where the shower circuit has no RCD protection at all. In that case a leaking element may not trip anything, which is more dangerous, not less.

What the electrician will check

When we visit for a tripping shower, we normally:

1. Check the shower’s power rating against the cable size and breaker.
2. Test insulation on the shower circuit and the element.
3. Inspect connections at the shower, the isolator switch and the consumer unit.
4. Test the RCD protecting the circuit.
5. Check earthing and bonding in the bathroom.
6. Explain the options and quote before doing the repair.

Sometimes the fix is a new element or a new isolator. Sometimes the shower is beyond repair. If the cable is too small, the circuit needs upgrading before a new shower goes on.

The rules for shower circuits

Bathrooms are what the wiring rules call a special location. The current standard is BS 7671:2018+A4:2026, the only version in force since 15 October 2026.

Under Part P of the Building Regulations, installing a new circuit is notifiable work, and so is much of the electrical work in a room with a bath or shower. That means it must be done by a registered competent person who can self certify, or notified to your council’s building control. The Planning Portal explains the routes. Ask to see your electrician’s scheme registration and check it with the scheme.

If you rent, the shower circuit is part of the fixed installation your landlord must have inspected at least every five years, as set out in the government guidance for landlords. Report a tripping shower to your landlord in writing.

Other things that trip in the bathroom

If the trip happens when the shower is off, look at the extractor fan, lights over the bath or a heated towel rail. Water through the ceiling from a flat or bathroom above can also cause trips. See water leaking through a light fitting. For trips with no obvious pattern, our main guide on why electrics keep tripping walks through the checks.

If you are in Enfield and your shower keeps tripping, switch it off at the board and leave it off. It is a quick fault to find with the right tests, and not one to live with.