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  1. #1
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    Default dimmer switch getting hot

    I have a kitchen chandelier with 5 lights. This is controlled 2 ways: 1st by a 2 way switch on either entrance to kitchen and
    2nd by a dimmer switch. The chandelier was wired to an existing dimmer 4 years ago and everything worked fine. Now when I turn on chandelier by dimmer switch, 1 to 2 minutes later, I noticed the plate was getting warm. I took off the plastic front plate and the metal front plate of dimmer was getting hot. I immediately turned it off. We thought the problem was the dimmer so we bought a new one and installed it but it still gets hot.
    I can't use it like this, what could be the problem?

  2. #2
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    Default Re: dimmer switch getting hot

    You don't say how many watts the 5 lights are. It may be you are exceeding the rating of the dimmer. Basically a dimmer uses a variable resistor to limit power the lights and it dissipates the power by producing heat. 5 100 watt lights would be 500 watts.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #3
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    Default Re: dimmer switch getting hot

    The variable resistor is old technology . Newer dimmers use solid state components to accomplish the same thing . Here's a good article . http://home.howstuffworks.com/dimmer-switch3.htm

  4. #4
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    Default Re: dimmer switch getting hot

    Can't say with certainity from here, but...the cause may be a corroded or loose/not firm connection up where the wires connect to the chandalier itself. This connection may have degraded over time.

    These types of light fixtures almost always come with stranded wire and getting a firm connection to the solid wire inside a wire nut can be tricky sometimes. An inadequate connection is virtually the same as having too small of a wire to carry the load involved. Heat is the result...and the more the wire heats, the greater the resistance becomes and so more heat develops.....etc.

    Or...it may be an inadequate connection between the solid and the stranded wire of the dimmer switch itself.

  5. #5
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    Default Re: dimmer switch getting hot

    Most residential dimmers bought at a big box store are the bottom of the line products. They typically have a rating of 300 watts. Most candle bulbs are 25,40 or 60 watts rated. You said you had a 5 bulb fixture. so the watts X the amount of bulbs should give you the total watts you are using through the dimmer.

    As stated above a dimmer uses a resistor to disipate the heat from dimming your bulbs. That is why your dimmer is warm.

    If you are using the 60 watt or higher bulbs I would suggest you get a dimmer with a higher rating. Then you should be ok.
    Harry

  6. #6
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    Default Re: dimmer switch getting hot

    i noticed you said you have a 3way (you said 2way but it would be a 3way if controlled at 2 locations) switch loop and that you only swapped out the switch at the dimmer. you said nothing about getting a special master/slave type 3way dimmer and the correct matched slave switch for the 2nd location.

    you said nothing about what size box the dimmer switch is in or if it shares other switches or other devices at the box. this is important to know because the dimmer switch needs room for putting off its heat and if it is in a shared location the rating has to be lowered especially if one or more of its tabs or fins have to be removed for positioning it on the box.

    if you could take a picture of the dimmer switch or provide more details of its location and info on the second switch that might help. where the power comes into the circuit, the kind of boxes metal or plastic, the type of wiring and cable and also if the circuit that gives power to the switch loop is a multiwire circuit. if the switches are rated for copper only, or for copper covered aluminum or copper and aluminum.

    you might try swapping out the dimmer for a standard 3-way switch but first trace out the circuit and verify all the wiring is correct assume nothing regarding wiring colors white is often used as a hot in a switched light loop wiring scheme.

    if switches especially dimmer switches are used close to or over their maximum rating they will get very hot. if you have two dimmers not a master slave set up they will also get to hot. when you break off one or more of the heat sinks their rating goes way down. mabe you got a 600 watt dimmer but broke off one or more of the tab fins so it is now rated for less than 450 watts and mabe you have another switch or device in the same box so it should be further derated for heat? if all else is correct and that is the case then you would need to upgrade the rating of the switch like to a 1000 watt dimmer and 3-way switch or slave. like mentioned there are different types of dimmers, varriable resistor solid state and stuff and their are different types of dimmers and switches like regular and those for low voltage. what kind of light fixture - does it have a power supply built in for low voltage halogens or fluorescents or regular incandescent bulbs? not a combo fan/light fixture is it?

  7. #7
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    Default Re: dimmer switch getting hot

    Quote Originally Posted by Blue RidgeParkway View Post
    i noticed you said you have a 3way (you said 2way but it would be a 3way if controlled at 2 locations) switch loop and that you only swapped out the switch at the dimmer. you said nothing about getting a special master/slave type 3way dimmer and the correct matched slave switch for the 2nd location.

    you said nothing about what size box the dimmer switch is in or if it shares other switches or other devices at the box. this is important to know because the dimmer switch needs room for putting off its heat and if it is in a shared location the rating has to be lowered especially if one or more of its tabs or fins have to be removed for positioning it on the box.

    if you could take a picture of the dimmer switch or provide more details of its location and info on the second switch that might help. where the power comes into the circuit, the kind of boxes metal or plastic, the type of wiring and cable and also if the circuit that gives power to the switch loop is a multiwire circuit. if the switches are rated for copper only, or for copper covered aluminum or copper and aluminum.

    you might try swapping out the dimmer for a standard 3-way switch but first trace out the circuit and verify all the wiring is correct assume nothing regarding wiring colors white is often used as a hot in a switched light loop wiring scheme.

    if switches especially dimmer switches are used close to or over their maximum rating they will get very hot. if you have two dimmers not a master slave set up they will also get to hot. when you break off one or more of the heat sinks their rating goes way down. mabe you got a 600 watt dimmer but broke off one or more of the tab fins so it is now rated for less than 450 watts and mabe you have another switch or device in the same box so it should be further derated for heat? if all else is correct and that is the case then you would need to upgrade the rating of the switch like to a 1000 watt dimmer and 3-way switch or slave. like mentioned there are different types of dimmers, varriable resistor solid state and stuff and their are different types of dimmers and switches like regular and those for low voltage. what kind of light fixture - does it have a power supply built in for low voltage halogens or fluorescents or regular incandescent bulbs? not a combo fan/light fixture is it?
    Way to much information for the average homeowner and very confusing.....Check wattages for the bulbs agaisnt the dimmers rating. If the bulbs exceed the dimmers rating get a higher rated dimmer
    Harry

  8. #8
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    Default Re: dimmer switch getting hot

    And the fact that it had been in for four years and working fine suggests it is something done recently. That something would most likely be replacement of lamps.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  9. #9
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    Default Re: dimmer switch getting hot

    Variable resistors are old technology . Newer dimmers use solid state components ( Triacs ) to accomplish the same thing .
    The old variable resistors probably did a better job of disapating heat .

  10. #10
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    Default Re: dimmer switch getting hot

    Quote Originally Posted by JLMCDANIEL View Post
    And the fact that it had been in for four years and working fine suggests it is something done recently. That something would most likely be replacement of lamps.
    Jack
    plastic switch cover was mentioned. if nothing else that's where i'd direct my suspicions and attentions. some plastic switch covers do a very good job of insulating holding the heat in the box especially if it is a plastic box. metal switch plates let more of the heat dissapate or escape into the room so then the dimmer doesnt heat up to much. if the switch cover was changed even before you noticed the dimmer overheating it could have caused or is causing the trouble being just enough of an insulator to either have the installation being under rated for the amount of heat or caused problems with the wiring insulation or the dimmer itself if you removed fins to mount the dimmer on the box and the switch plate you have to derate it even more.

    if the switch plate cover was changed or a new style dimmer was used with a different style switch cover (so had to take off a tab/fin) thats were i'd direct my attention assuming everything else was rated and remains installed as it should be and you didnt overlamp the light fixture (like putting 75 watts bulbs in a 60 watt max socket or 60 watts bulbs replaced 40 watts bulbs for example).

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