"The Natural Philosopher" wrote in message ...

Funnily enough, you can modify a really beefy dimmer to work on 12V AC
like you get from a toroidal type LV transformer. A bit lossy, but it
works apparently. The Triac needs uprating for the larger currents, and
the resistor needs to come down in value, but the triac doesn't need to
be a 400V type anymore.

/s/modify/totally redesign, surely. The usual type of mains voltage dimmer
uses a diac in the triac triggering circuit, with a breakdown voltage of
30-40V. To make it work on 12V you'd need a totally different firing
circuit. And the voltage drop and power loss in the triac would not be
negligible. The idea is a complete non-starter (literally!) IMHO. Leave
the dimmer on the primary side of the transformer.

Normal (wall) lightswitches and dimmers can now be used in bathrooms
provided they are in zone 3 or beyond -- i.e. more than 0.6m (horizontally)
from the edge of the bath and/or shower tray.

--
Andy