Why is my shower cutting out all the time?

Question

Is my shower cutting out because of water pressure in the house? It seems to happen more frequently when someone else uses a tap or flushes the toilet, which makes me think it could be that rather than a fault with the shower unit. But it even happens when I'm the only one in the house. This isn't even an old unit, installed around a year ago (mira)

William · Accepted Answer

Usually low water pressure, but if it has been happening before you may have to replace thermal cutout switch.

Teodor · Answer

If it’s happening more often when someone flushes the toilet or uses a tap, that does point towards a pressure/flow issue rather than the shower itself. Electric showers (like Mira) have a minimum flow rate and pressure requirement, and if the supply drops suddenly they can cut out or cycle hot/cold to protect the heating element.
However, if it’s also happening when no other water is being used, it could be:
Low incoming mains pressure or restricted flow (partially closed stop tap, faulty pressure reducing valve, blockage in pipework).
A clogged inlet filter inside the shower.
A thermal cut-out activating due to overheating.
An electrical issue (loose connection or undersized circuit).
I’d suggest checking that the main stop tap is fully open and asking your water supplier about your mains pressure. If that’s fine, a qualified electrician/plumber should inspect the shower unit, inlet filter and supply to rule out a fault with the unit or installation.

Sean · Answer

Yes this is based on the element either overheating or a difference in load being pulled is making the RCD trip.

Both are a result of pressure change or low pressure meaning the pump or element are over working.

Long term result of this is that the shower could burn out.

Chris · Answer

You need to do some maths. Find out kW of the shower if its 8.5kw. Eg. 8500 ÷ 230 = 36.9amp. Make sure your mcb is now lower than 37 amp mcb

Kelsey · Answer

Hi. It can be a combination of things ie water flow rates and shower specs.

Harry · Answer

1. Low water pressure / flow
•	If the flow drops too low, the shower overheats
•	The thermal cut-out trips
•	Shower goes cold or shuts off
•	Comes back after 30–90 seconds once it cools

Common reasons flow is low:
•	Blocked shower head (limescale is a big culprit)
•	Partially closed isolation valve
•	Old or kinked pipework
•	Mains pressure issues (worse at peak times)

👉 Try running the shower with the head removed.
If it stays on = blocked head.

2. Overheating (even with decent pressure)
•	Electric showers are basically tiny kettles.
•	Things that push them over the edge:
•	Shower set too hot
•	Summer mains water already warm
•	Long runs on full heat
Fix:
Turn the temperature down slightly and increase flow.
Hotter better if it keeps cutting out.

3. Electrical supply issue
Less common, but serious if this is it.
Possibilities:
•	Loose connection in the isolator
•	Failing pull cord switch
•	Cable overheating
•	RCD/RCBO nuisance tripping
•	Shower goes completely dead
•	Needs isolator flicked off/on
If it’s electrical, don’t ignore it.

4. Faulty thermal cut-out or heating element
•	Pressure is good
•	Shower head is clean
•	Still cuts out randomly

Then the shower unit itself may just be on its way out.

Why is my shower cutting out all the time?

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