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One of my light switches has started over heating/melting all of a sudden. This is definitely a new development because this has not happened in the year that we have lived here. I have 9 6W LED bulbs connected to a Lutron Caseta light switch that's rated for 500W. I replaced the melted switch with a new one this morning and replaced all the bulbs with brand new ones too, but it seems to be getting quite hot again. More so than getting hot, it smells like burning plastic.

It seems isolated to one light switch. It seems to be overheating after being on for several hours. Should I get a switch that's rated for a higher wattage? Why would that be an issue all of a sudden? Could there be a voltage change? Could some wires behind the walls have gotten loose?

There are 2 other switches in the junction box that seem fine.

Edit: added photo enter image description here

  • It sounds like you have a short or bad connection somewhere. You have 54 Watts total of light, you don’t need a larger watt dimmer. – Tyson Oct 8 '17 at 23:00
  • Any guidance on how I can find this wire? Is it in the junction box or behind a wall? How could it have gotten loose? – mergesort Oct 8 '17 at 23:01
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    Can you post photos of the culprit dimmer and the wiring attached to it? – ThreePhaseEel Oct 8 '17 at 23:05
  • I've attached a photo. You can see the screw hole that's black from the melting/burning! One thing to note is that I have the 3 grounds connected to each other because I'm not sure if the box is grounded. – mergesort Oct 9 '17 at 0:57
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It sound like you have a partial ground from a pinched or nicked wire. This would draw a large amount of current but not enough to trip the breaker.

If the switch is overheating I would suspect the partial ground is in the load side of the circuit after the switch.

Check the circuit with an ammeter to determine the current draw. If you don't have one remove all your lamps from he light fixtures and see if it still gets hot. You could also series a lampholder with an incandescent bulb to the switch with all othe lamps removed. If the lamp lights up you have current flowing to a partial ground.

Good luck!

  • I do have a multimeter! Dumb question, but how do I check the current draw in the circuit? Will I electrocute myself or are there any other risks? What am I looking for? – mergesort Oct 9 '17 at 0:54
  • Also, the three grounds are connected to each other. Not sure if that makes a difference. – mergesort Oct 9 '17 at 0:58
  • The other thing I noticed too is that even when the lights are off it still smells. It doesn't get too hot, but still smells like burning plastic – mergesort Oct 9 '17 at 1:11
  • Most digital multimeters cannot test more than 10 amps of current. If it is greater it will blow the internal fuse in the meter. In order to test current you would want alligator clips on the test leads so you can keep it connected in the circuit without touching it. You would need to shut off the breaker, put the meter in series with the switch, select the AC current range, leave the switch off and turn the breaker on. If there is any current flow with the switch off you have a partial ground or short in the system. With the switch on you should only get what the lamps are rated for. – ArchonOSX Oct 9 '17 at 11:14
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    In case the OP doesn't know what they are, you can also get a clamp meter that just hooks around an exposed wire and can read the current that travels through it. You can get cheap ones for around $20, and no wires need to be disconnected or even touched. – JPhi1618 Oct 9 '17 at 14:41

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