Warm Light Switch Cover

On an inspection I carried out on Monday, I noticed a wall mounted light switch cover become very warm after just a couple minutes.
So if you do not already do so, it may be a good idea when you turn on a light always put your hand on the cover plate.

Hi to all,

Good point Carl, but it is worth remembering that if he switch is also a dimmer, that these will always run much hotter than a standard switch due to the resistance generated by the variable rheostat which controls the light.



Thanks Gerry,

Does that mean I get a green a square & NACHI will promote me from “unhelpful tosser”, to just plain “tosser”

Great tip but use the back of your two middle fingers ( More sensitive )an old Electricians trick to find hot breakers .
Roy Cooke

Nice one Roy thanks

A warm cover could also indicate the presence of alluminum wire.

I don’t believe a proper load capacity and wired dimmer switch should operate much hotter than a normal toggle switch. I use a thermometer on the switches and refer to a sparky when temperature changes of more than 10 degrees are noted. Dozens of switches have been replaced and or rewired from my inspections with no complaints from the seller and or the sparkys called to further inspect/service.

The dimmers made in the last decade or longer are much warmer but not from the rheostat. The heat comes from the triac or thyristor that is used to drop the output voltage. A large heat sink is also present to help shed the heat.

Be aware that dimmer switches can only handle a specific amount of light load. You can typically purchase dimmers that are rated for 600 or up to 1,000 watts of lighting. Light bulbs are usually clearly marked as to their wattage. Determine the total wattage of the bulbs that are being controlled by any one dimmer. Purchase the correct size dimmer switch to suit your needs. But keep in mind that the metal heat sink plate on the front of many dimmers can be altered so that you can place multiple dimmer switches next to one another. If you break off the side tabs of the heat sink, as allowed in the instructions, you need to derate the capacity of the dimmer. If you snap off the tabs on both sides of the heat sink a 600 watt dimmer becomes a 400 watt dimmer.

“Tim Carter @ Ask a Builder”

From my educational [Interactive Report System](http://www.abouthomes.info/files/NACHI/IRS for NACHI members.pdf):

Very often I have found dimmers for lights being used for ceiling fans and visa verse. It is important to verify this especially if it is already displaying unusual symptoms of a problem.

It can also never hurt to mention that most compact florescent bulbs are not designed to operate under reduced voltage.

If you notice the bulb, or as often as not, the switch ‘buzzing’, check the fixtures for the CF bulbs.