On Sat, 10 Nov 2018 17:04:58 -0000, wrote:

On 11/10/18 11:12 AM, Steven Watkins wrote:
On Sat, 10 Nov 2018 16:05:22 -0000, wrote:

On Saturday, November 10, 2018 at 10:33:19 AM UTC-5, Steven Watkins
wrote:
Why do houses have a switch to turn the shower off, either a cord on
the ceiling or a switch in the hall?

Can you please describe the situation more fully. Does this switch
turn off
the water, or does it turn off electricity (such as for a light in the
shower compartment)?

Commonplace in the UK. Circuit from fusebox feeds switch on bathroom
ceiling or in the hall. This feeds the 8kW (ish) electrically heated
shower. The switch disconnects the heater in the shower (pointlessly as
the shower has it's own controls). It would be like turning off your
microwave oven at the wall every time you'd finished cooking.

What we in the US have to understand is the British seem to put a switch
on everything.

My son lives in London, and in his flat (aka apartment) even the regular
wall outlets each have a switch, right in the same housing.

Those are for convenience. I can switch something off without having to unplug it. And before you say "use the switch on the device" there might not be one, or the device might be out of reach or further away.

Also most water heaters are electric, and are the on-demand type,
located in the bathroom (aka "the loo")

Only for the shower. The taps are heated by the central boiler which also heats the radiators.