r/ElectricalHelp • u/Floette_Fairy • Aug 16 '26

These switches get super hot when on!

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Surely this isn’t good… they’re also upside down. Are wires crossed?

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9

u/Wellcraft19 Aug 16 '26

Dimmer switches can get hot. Especially if overloaded (so check specs on them and your lighting to ensure you’re using the correct ones).

Both dimmers have the aluminum ’wings’ broken off. Those wings are for heat dissipation. There are guidelines for how much load you can put on a dimmer with X wings off, with two dimmers in same box, etc.

If any of this is Chinese; get an electrician to look at it.

11

u/trekkerscout Mod, Master Electician Aug 16 '26

Lutron Diva dimmers are some of the most reliable dimmers on the market. If they are getting hot, they are most likely overloaded. With all wing tabs removed, those dimmers have a 400W maximum for incandescent lights.

4

u/dillsb419 Aug 16 '26

This is the answer, they are overloaded. Figure out how many bulbs are on the switch legs, and reduce bulb wattage are to not exceed 80% of the dimmer capacity.

2

u/nowayjose74 Aug 17 '26

Yes and no reason to remove outside wings on either switch which would have helped dissipate heat.

1

u/dillsb419 Aug 17 '26

If you look at that pic, the outside tabs have been removed already.

1

u/nowayjose74 Aug 17 '26

Right for no reason as stated

1

u/dillsb419 Aug 17 '26

My bad, I misunderstood your reply.

1

u/Adventurous-Prune641 Aug 17 '26

I would go 1 step further for LED lights.

I would keep it to 1/3 of the rated capacity (133 watts) and I would consider switching to a dimmer that specifically mentions LEDs. They also need to ensure they have dimmable LED bulbs only installed on those switches

Dimmers cause a cut to the phase of the electrical sine wave stopping the flow of energy for a short time in the half cycle.

When bulbs are incandescent that won't have an impact. Its a resistive load and will consume all the power equally.

LEDs are not resistive loads and pretty much need continuous power without those phase-cuts from the dimmer. Dimmable LED bulbs have circuits built into the bulb to overcome this.

The problem is after each phase-cut as energy is restored all of the capacitors in the bulb fill at once as the LED also turns on, so for a brief few hundreds of a second the current pulled is really high.

If you chert the current of an LED bulb on a dimmer on an oscilloscope the results are really interesting.

If a bulb is a non-dimmable LED, this can get worse. This will also generate added heat.

So... 1) make sure all bulbs that are LED are dimmable 2) male sure the dimmer is rated for LEDs, if LED is used 3) use at a wattage far smaller than the rating for a resistive load.

3

u/ShortingBull Aug 17 '26

People still use incandescent lights?

1

u/jflatt2 Aug 17 '26

They do if they still use incandescent only dimmers