We've just installed two new light switches, both in a brushed-steel finish.
One is a conventional toggle-switch, and next to it is a touch-sensitive
dimmer-switch, which is always very warm to the touch. I'm a bit concerned -
is this normal?
Depends what you mean by "very warm". If it is uncomfortable to hold
your fingers on the switch for any length of time then there's probably
something wrong somewhere - perhaps the dimmer switch is incorrectly
specified for the load? What are you dimming, and what is the
specification of the switch?
On the other hand, if you just mean that it is "obviously warmer" than
the ordinary switch, especially if the temperature drops when the light
isn't dimming (i.e. is at full brightness) then it's probably normal.
Check the documentation that came with the switch, it might tell you
what to expect.
Martin Angove: http://www.tridwr.demon.co.uk /
Don't fight technology, live with it: http://www.livtech.co.uk /
Yes. Dimmers always drop a volt or two in use - at say an amp for a mild
250W setup, its likely to be kicking out a couple of watts of heat. Most
of that will come out the front plate.
If its got complex electronics in it as well it may even be more.
We have the exact same problem, we bought our swtiches from homebase, the
dimmer switches are definetly warm. We have just assumed that its warmer
than the plastic ones before becasue the metal face plate conducts heat
better. Husband is an electrician and had to double check the wiring was OK
becasue of it, but its all fine!
As heat is energy reducing it through the front plate obviously means the
deficit goes somewhere else ...ie out the back!
Thermal conductivity of plastics can range from 0.2 to 500 W/mK (specialistic
plastics) so I'll stick with my assumption of ignoring the % that goes into the
wall, especially as most walls are insulated! So a quick calc with convection,
conduction thermal resistances and ignoring contact resistances....
At steady state conditions are reached the convection from the outside of the
plate to the air in the room will dominate the heat dissipation.
Stuff the coat, I'll get me annorac
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