On Saturday, November 10, 2018 at 11:12:47 AM UTC-5, 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.

Ah. I understand now. The most common arrangement in the U.S. is a
tank heater that keeps 40 or 50 gallons of water hot at all times, which
feeds the shower and all other hot water needs in the house. My tank
is kept heated by a gas burner.

Cindy Hamilton