On Sunday, 14 February 2016 21:59:53 UTC, Stephen wrote:
Hello,

I am thinking of installing an electric shower as a back-up to the
combi boiler. I have talked about this before but not got round to it!

Can anyone tell me what are the rules regarding shower isolator
switches? I could not see anything in the OSG; where should I have
been looking?

From my experience, electric showers always seem to have pull cord
isolators in the bathroom. Is there a reason for this? I am wondering
why I don't see wall switches, like the ones used for ovens, on the
walls outside bathrooms?

I am thinking about high current electric showers but whilst we are
talking about it, how do the rules differ (if at all) for other types
of shower. I am thinking that pumped showers come in two types:
showers with an integral pump or ones where the pump is separate. I
presume these are often isolated by a switched FCU in the airing
cupboard or somewhere discrete, not in the bathroom?

Thanks,
Stephen.

You can have either a pull switch inside the bathroom or a wall switch outside.
Your choice, but must be double pole ie both live and neutral switched.
This applies to all electric devices in the bathroom.
And not every device is suitable for use in a bathroom.
Have a read at:-

http://www.denmans.co.uk/info_bathroom_zones.html