Electric shower running cold, tripping or dead: fix or call

What a shower can and cannot tell you

Most electric showers cannot show a code. The common ones have a knob, a power selector and one or two neon lamps, and everything they can say is in whether those lamps are lit. Bristan are the exception, with LP, E1, E2, E3 and CL on a small temperature display — and E1 means different things on different Bristan showers. Mira encode thirteen faults, lettered A to M, in the colour and rhythm of two lights, and reading one takes two observations: the Start/Stop and Status lights as they are, then the Status sequence again while Start/Stop is held. Triton publish no codes at all, only a numbered fault-finding matrix and two named lamps, so a "Triton fault code" found elsewhere is not theirs. Redring split every symptom into what the owner checks and what the qualified service person checks, and label the two. That structure — the owner's list and the professional's — is the one this guide follows.

The reset, and what it does not do

The reset for an electric shower is the pull cord or the wall isolator. Switch it off and give it a moment — none of the four brands publishes a duration, so ten to fifteen seconds is this site's margin rather than a manufacturer's figure, and Mira's own wait for a shutdown to finish is fifteen — by which time the control electronics have lost their state: a transient fault clears and any protection that latched re-arms. Then start the shower and watch what it does; Mira's commissioning sequence runs it for at least five minutes at showering temperature before judging it, because a shower that starts is not a shower that holds.

Four brand habits matter more than the reset itself.

• Mira Advance runs a phased shutdown after you press Start/Stop, and Mira instruct in capitals that you do not isolate the power at the pull cord until the water has stopped and the lights have stopped pulsing. Cutting the supply mid-shutdown is what produces code M — a sequencing message, not a fault, and a change of habit rather than a part.
• Redring fit a cyclic over-temperature cut-out that is restored by running the shower cold: not by isolating it, not by waiting with the power off, but by letting cold water flow through until the temperature comes down. It is step seven of their eight checks for a shower running cold, and it is the opposite of the usual advice.
• Triton protections mostly reset themselves. The TP temperature protection restores power to the elements when things have cooled and the low pressure cut-out restores it when pressure returns, both documented as automatic. The abnormal safety cut-out does not reset at all: it is a non-resettable device, and Triton say a qualified engineer has to replace it after the underlying fault is repaired. Switching a Triton off and on clears nothing that matters.
• Bristan publish no reset sequence. For an LP display caused by the thermal cut-out, the Joy Care guide says turn the unit off and wait five minutes — five specifically. For LP caused by low pressure, wait until the pressure increases. Their standing instruction for anything abnormal is to turn off at the mains electrical supply and consult them.

Running cold

Inside the casing is a small heater tank with elements that energise when the unit senses water passing through and drop out when it stops. Cold water at the head therefore means one of three things: the elements are not being powered, the shower has deliberately switched them off because too little water is passing, or an element has failed. The first two are yours to check, in that order, and the third is not.

Power first, and the manufacturers agree on the order — Triton's matrix and Redring's eight-point checklist both open at the consumer unit. Look for a tripped device on the shower circuit, then confirm the isolator or cord is on and the neon on the unit is lit. Cord on and neon dark puts the fault upstream of the shower. A tripped breaker changes the diagnosis entirely; the tripping section below is where to go. Then rule out the settings: highest power position, temperature knob not at its coldest, and a full minute of running before you judge — on economy power in January the water may only ever be tepid, and nothing is wrong.

Then flow. These units cannot safely heat water that is not moving fast enough to take the heat away, so each has a protection that cuts the elements when pressure or flow drops, and leaves the water running. Triton's low pressure indicator is exactly that: power to the elements is removed and the water keeps coming. The test is to unscrew the showerhead and run the bare hose into the tray. Warm water without the head means the head was the restriction and the protection was doing its job — descale or replace it. With the cord off and the servicing valve on the inlet pipe closed, the inlet filter behind the connection can also be removed and rinsed; it is where grit and scale settle.

If the neon is lit, the flow is unrestricted and the water is still cold, you have reached the end of the owner's list. What remains — an open-circuit element or a thermal cut-out — sits behind the cover.

The thermal cut-out, three ways

Every electric shower has one, and the same three words describe three different devices. Their job is the same — sense a temperature inside the unit that should not be there and disconnect the elements — and what happens next is not. Redring's resets by running cold. Bristan's resets after five minutes off. Triton's does not reset and needs replacing. Whichever you have, deal with the flow before using it again: a scaled head, a blocked inlet filter or a hose kinked behind the riser rail is what raised the temperature, and turning the temperature down a little at higher flow stops the device tripping. Both Bristan and Redring name a temperature set too high at low flow as the ordinary cause. If it trips again after a clean head and a clear filter, stop resetting it and get it looked at; the device is reporting something it will keep reporting.

Completely dead

No neon, no water, nothing when you pull the cord. The circuit is dedicated, so the chain has only four links: the breaker, the cable, the isolating switch and the shower. Start at the consumer unit. Then the isolating switch, which is where most dead showers actually are: a ceiling pull cord is a mechanical switch operated wet-handed several times a day for years, and a cord that has stopped clicking, or whose indicator no longer changes, is a switch that has worn out. Triton define their power-on neon as lighting when the supply is switched on at the isolating switch, which makes it a direct test of whether power has reached the unit. A replacement pull-cord switch is an electrician's job on a 40-amp circuit in a bathroom, and it is the common outcome.

Tripping, and a burning smell

These are the two danger-rated conditions in the category, and the instinctive response to the first makes it worse.

The shower has its own circuit with two protective devices on it: a breaker, which responds to too much current, and — required by BS 7671 for a bathroom — a 30 mA RCD, which responds to current escaping to earth. Note which one operated. The breaker on its own suggests overload, and the usual story is a bigger shower fitted to wiring and a breaker chosen for the smaller one; that version trips a few minutes in, under load, rather than at the moment of switch-on. The RCD points at leakage, and the classic path in a shower is through the water: the element's sheath cracks and the water in the tank connects it to earth. Condensation inside the pull-cord switch, or water reaching the electronics from a failed seal or split hose tail, trips the same device for the same reason. That device is protecting a wet, barefoot person standing inside a metal-framed cubicle, and it has just done so. One reset is reasonable. A second trip means leave it off and book a qualified electrician, whose first task is to establish whether the leak is upstream or downstream of the isolator. Triton's published remedy for a fuse or breaker that goes again is to consult a qualified electrician; Bristan's is not to operate the shower if the water stops during use or is leaking from the unit, and to turn off at the mains electrical supply. The tripping page has the causes in full.

A burning smell, hot plastic, or a pull cord or shower that is discoloured or scorched is an overheating connection. A 9.5 kW unit draws around 40 amps continuously through the small terminals of a ceiling switch and a terminal block inside a wet enclosure, and a connection that has worked loose heats every time the shower runs. A whole cable run that smells warm rather than scorched points at a cable undersized for the shower on it. Switch the circuit off at the consumer unit — it is the largest breaker in the board, usually 40 or 45 amp — and leave it off. None of the four brands publishes a fault entry for this; what they publish is the instruction to isolate, and Redring's professional checklist is headed, in capitals, with switching off the electricity and the mains water at the local isolator before the cover comes off.

Water where it should not be

Water from the small tube under the shower means the pressure relief device has ruptured, and it is a symptom, never the disease. The outlet blocked — a scaled spray plate, a kinked hose, a head with an eco restrictor, or a new installation purged with the head fitted — the elements kept adding heat, the mains kept pushing, and a deliberately weak part gave way to save the tank. Triton print the rule under their own table: identify the cause before fitting a new PRD, and commission the unit with the showerhead removed. Pull the cord, close the servicing valve, let it stand because the water can be hot, and find the blockage before ordering anything. A shower dripping from a visible joint is a washer or a hose; water coming out of the casing itself is the manufacturers' instruction to stop using it, because the terminal block and the element connections are inside that enclosure. An internal tank leak is normally a replacement unit.

Water suddenly scalding is the same mechanism from the other side: too little water through the shower for the heat it is adding. Clean the head, open the temperature control towards cooler, reduce the power setting — Bristan's three remedies, in that order — and remember that the incoming mains is warmer in summer, so a setting that was right in February is too hot in July.

Fitting a bigger shower

A 10.5 kW shower gives a better shower than an 8.5 kW one, especially in winter, and the constraint is not in the shower. Moving from 8.5 to 10.5 kW takes the current from roughly 37 to roughly 46 amps, and the cable, the breaker and the isolating switch were sized for the smaller unit. The failure mode is not that it does not work; it is that everything warms up under load — the burning-smell page again. Read the kW on your rating plate, note the shower breaker's rating at the consumer unit, and have an electrician confirm the cable before buying anything. Do not fit a larger breaker to stop a new shower tripping: the breaker protects the cable. The higher-kW page sets out the regulations it quotes.

The legal position is worth getting right in both directions. A room containing a bath or shower is a special location under Approved Document P, and installing a new circuit, or any addition or alteration to a circuit inside the zone around the shower, is notifiable work normally done by a scheme-registered electrician. But replacing a shower on its existing circuit is a repair, and repairs are not notifiable anywhere — the Welsh Approved Document P names electric showers specifically. Nobody should tell you that swapping a shower is restricted work; nobody should tell you a new 45-amp circuit to the bathroom is not notifiable either.

Who to call, and what it costs

• You, for the supply check, the settings, the showerhead, the hose, the inlet filter and the brand's own reset. Most cold, cycling, scalding and low-pressure complaints end here at no cost beyond a showerhead.
• A qualified electrician for anything on the supply side: a breaker or RCD that trips again (an electrician's visit plus the element or the switch, £80 to £260 on the code page; a rewire of the run if the circuit is undersized), a worn pull-cord switch (a replacement fitted, up to about £140), a burning smell (a remade connection or new switch at the low end, £80 to £300; a new circuit if the cable is undersized), and any question about fitting a higher-kW unit (£150 to £700, the top end being a new circuit and notifiable).
• A shower engineer or the manufacturer for what is behind the cover: an element or thermal cut-out replacement is typically the low three figures fitted, a Triton safety cut-out £80 to £220 plus whatever caused it, a Mira flow valve or board £90 to £260, a Bristan thermistor or solenoid up to £220 and free within the guarantee. On a shower more than about five years old, price a new unit fitted alongside the repair.

Sources

• Triton T80 Easi-fit+ Installation and Operating Instructions 2181509N (September 2025): the fault-finding matrix, the low pressure and power-on indicators, the TP and abnormal safety cut-outs, and the PRD note.
• Bristan Glee (576755) and Joy Care guides: LP, E1, E2, E3 and CL, the five-minute wait, "Do not operate the shower if ... water is leaking from the shower unit itself", the 0.7 bar minimum, and the guarantee's reference to the Wiring Regulations and Part P.
• Mira Advance installation and user guides: the thirteen lettered indications, the two-step reading, the phased shutdown and code M, and the five-minute commissioning run.
• Redring troubleshooting checklists (Water too COLD, Water too HOT, dripping from the bottom of the shower): the cyclic cut-out reset by running cold, the twenty-second adjustment wait, and the capitalised isolation warning on the professional checklist.
• Approved Document P (2013), regulation 12(6A) and paragraph 2.7, and the Welsh Approved Document P note (m), on notifiable work and repairs; BS 7671 on 30 mA RCD protection in bathrooms.
• Cost brackets are those on this site's cross-brand shower pages and the Triton, Mira and Bristan code pages, each with its own sourcing.