dimmer keeps burning out

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  #1  
Old 04-10-10, 04:33 PM
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dimmer keeps burning out

i replaced a regular light switch with a dimmer. Twice it's burned out. Any ideas what might be causing this?

Thanks
 
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  #2  
Old 04-10-10, 05:57 PM
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What type of lights are you dimming? Incandescents? Flourescents?

Mechanical dimmers typically generate a lot of heat when operated for long periods of time. They are made with aluminium fins to distribute that heat. If place in an area with higher heat inherently or very poor air circulation, it can be difficult for the cooling fins to keep up. If you're using a mechanical dimmers and they're malfunctioning frequently, it is possible that electronic dimmers may have more success because they typically have far less issues in overheating.

Without more specifics, it's difficult to be certain, but that would be my guess.
 
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Old 04-10-10, 06:00 PM
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Too much wattage. Non dimming CFL lamps on dimmer. Poor quality dimmer. Wiring the dimmer hot. That is what is off the top of my head. What is happening?
 
  #4  
Old 04-10-10, 07:56 PM
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Its an older 8-bulb brass ceiling fixture (guessing 20 - 30 years old) with 120v 40w round incandescent bulbs. I installed a single-pole Lutron digital fade dimmer in a double gang electrical box with a another dimmer (same kind). (It's a single-pole fixture).

The dimmer worked fine for a few weeks then went dead. Replaced with a new dimmer and same thing.

According to the instructions it doesn't matter which wire is connected to which terminal screw as long as the ground wire is connected to the ground wire in the box.
 
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Old 04-10-10, 08:31 PM
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installed a single-pole Lutron digital fade dimmer in a double gang electrical box with a another dimmer (same kind).
Two dimmers in one box can produce a lot of heat. Dimmers max wattage is less the greater the heat. Maybe the other has less load.
8-bulb brass ceiling fixture.... with 120v 40w
That's 320 watts minimum and with derating for the other dimmer you probably need at least a 500 watt dimmer.
 
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Old 04-11-10, 08:06 AM
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the Lutron dimmer is 600w
 
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Old 04-11-10, 10:34 AM
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First thing I would do is is try a different brand/type of dimmer.
 
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Old 04-11-10, 11:03 AM
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i just tried putting on another dimmer (same brand because I had one) and it immediately tripped the breaker. i then tried a regular rocker switch and immediately blew the switch and tripped the breaker. could i have screwed up the wiring somehow? but if that was the case they wouldn't have worked for a week right??
 
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Old 04-11-10, 11:20 AM
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Ok, It sounds like you got something wrong. Sounds like you have a dead short from hot to neutral. Something may have happened to the fixture but lets start here: What wires are in the box and what is connecting to the switch? Pictures are good too.
 
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Old 04-11-10, 12:32 PM
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this is what i have (dimmer 2 is the one that keeps blowing):

 
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Old 04-11-10, 01:13 PM
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Ok, That looks pretty straight forward. Next thing to do is to disconnect the light (you might be able to drop only the canopy to access the wires) and see if you can turn the switch on without blowing the breaker or switch.
 
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Old 04-12-10, 11:53 AM
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ok, I disconnected the light. before putting on a new switch i used a voltage tester. both the red and black wires going to dimmer 2 are hot. is it possible that the red wire coming out of the middle feed wire should be connected to the black group and the black from the middle feed wire should be going to dimmer 2?
 
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Old 04-12-10, 12:05 PM
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It sounds like the cable with the red and black wire is your incoming feed cable with two seperate circuits on it. You can check this by turning off breakers and identifying which wire is controlled by which breaker. I assume that each of the other two cables are running to a load to be controlled by a dimmer.

Provided this is true, you have two options.

Option 1: Cap off one of the incoming circuits (either red or black) and feed both with the other circuit.

Option 2: Feed dimmer 1 with the black hot and feed dimmer 2 with the red hot, tying each to one of the black load wires. This would split up the load between the two circuits and is probably the original intention.
 
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Old 04-12-10, 04:22 PM
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Originally Posted by jimyyz View Post
ok, I disconnected the light. before putting on a new switch i used a voltage tester. both the red and black wires going to dimmer 2 are hot. is it possible that the red wire coming out of the middle feed wire should be connected to the black group and the black from the middle feed wire should be going to dimmer 2?
What wires/cables do you have in the light box? What color wire was connect to the light? When you say both wires are hot, how did you test? Did you use a meter between the hot and neutral/ground or just a non contact tester?
 
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Old 04-12-10, 04:52 PM
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Ok, so i checked the red and black as per RHefferan's suggestion. it seems that my voltage tester is giving me erroneous readings. As i move the sensor around the exposed red wire sometimes the audible signal goes off sometimes there is no signal. But it's not just blips I can get it to make a signal continuously. Anyway, the red is definitely NOT hot.

However, I think i may have solved the problem. The light switches originally were reversed. The left switch controlled the right light and the right switch controlled the left light. After the electrician replaced the left light with 4 x 4" pots I put in the dimmers. At the same time I reversed the wires so the correct switch turned on the correct light. And while cleaning up the mess I used a new piece of wire to connect to the dimmer. Could it be the new piece of wire I used which is 14 gage 300 volts that is causing the problem? As Ray pointed out i have 320 watts being used.

thanks for the help everyone.
 
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Old 04-12-10, 05:02 PM
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Original post deleted because OP posted asI was writting.
it seems that my voltage tester is giving me erroneous readings
You should never use a non-contact tester except as a quick double check power is off. You need to use a contact such as a test light, solenoid tester or analog multimeter.
 

Last edited by ray2047; 04-12-10 at 05:37 PM.
  #17  
Old 04-12-10, 08:07 PM
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i do very little electrical work (put on a dimmer, change a fixture) but i probably should get a multimeter anyway. thanks

i went to my big box stores. standard interior wiring is 300v which means it can't be the wire. back to the big box for a multimeter or time to call an electrician?
 
  #18  
Old 04-14-10, 05:32 PM
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Tolyn, there is a picture above.

I put a regular rocker switch on and it didn't blow. I then put up one of those basic light 1-bulb light fixtures that you typically see in an attic or basement. The Light works fine.

Does this mean that it was the fixture causing the problem. Does it happen where a fixture works fine for 25 years and then goes on the fritz?

One last question if a light works does that mean the wiring is fine? To clarify, the light worked just fine for several weeks when I first put on the dimmer.

thanks again
 
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Old 04-14-10, 06:50 PM
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Yes, it sounds like you have something up with the fixture. Fixture wiring does go bad if they are over lamped (too high of wattage light bulbs) or the insulation just fails.

Remove all the light bulbs (sometimes a bulb will go bad a cause a short) Take your new multimeter (you did buy one right? ) set it to ohms Ω. Connect one lead to the black wire and the other to the white. You should get no reading. Now connect one lead to the black and one to ground or the metal of the fixture. Again, you should get no reading. Now go to each bulb and connect one lead to the screw shell (the threaded outside) and the other to the very middle of the end. you should get some reading higher than zero. What you get will depend on the wattage of the bulbs. If you get zero ohms on any reading, that is a short. To see what this looks like just connect the two leads of the multimeter together.

Any questions, just post them here.
 
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