®An electric shower upgrade looks like a straight swap. Sometimes it is. Sometimes it’s an electrician, a chased wall and a new cable run back to the consumer unit. The difference is the kW rating, and it’s worth raising early.
Why customers choose electric
- Independent of the boiler. The shower heats cold water itself, so it isn’t affected by hot water running elsewhere in the house.
- Efficient. It heats only the water that’s used.
- The trade-off: the unit is on the wall, so it’s bulkier and less sleek than a concealed thermostatic valve.
The kW decides the cable
Electric showers typically run from about 7.5 kW to 10.5 kW. A higher rating heats water faster and gives a better flow, and it needs more current.
| Shower rating | Typical cable size |
|---|---|
| 7.5 kW | 6 mm² |
| 8.5 kW | 6 mm² |
| 9.5 kW | 10 mm² |
| 10.5 kW | 10 mm² |
The question to ask: what’s on the wall now? Moving from a 7.5 kW or 8.5 kW unit up to 9.5 kW or 10.5 kW commonly means a new, heavier cable back to the supply. That’s electrical work, done and certified by a qualified electrician, not a swap.
Treat the table as a guide to start the conversation. The electrician confirms the cable, protection and route for the actual installation.
When it’s thermostatic instead
A thermostatic shower uses water already heated by the boiler. Nearly all the workings hide behind the wall, so it looks cleaner. Two things to check:
- Pressure. The water has to come up from the supply, so the flow depends on the house.
- Wall depth. A concealed valve needs a wall or bulkhead deep enough to take it. If there isn’t room, plan a box-out or choose an exposed valve.
Power showers and pumps
Pumps range from a simple shower pump to a whole-house system. The right one depends on the existing plumbing and water pressure, so it’s a survey decision, not a product to pick off a page.
Put the conversation in the design
If the shower needs a box-out for a concealed valve, draw it. In KBB Go a bulkhead or pipe box goes in from the wall’s right-click menu in seconds, so the customer sees where the box goes before it’s built.