Help needed with a dimmer replacement

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  #1  
Old 01-18-07, 09:50 AM
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Help needed with a dimmer replacement

Hello --

The dimmer in my dining area is working partially. The round, oversized knob can only be used to turn on and off the lights by pressing on it. Rotating it does not dim anything.

All I want to use the dimmer for is a light fixture with six 60W bulbs.

After shutting off the circuit for the dimmer at the panel, I realized that within the same circuit are the hallway and kitchen lights. Nothing else.

Upon removing the large lastic cover, I see on one side the dimmer and on the other a light switch.

The dimmer has two black wires and no indication on the unit as to what those identical wires are for. Each wire from the old dimmer was pigtailed to just two wires coming out from the metal box. One is BLACK and the other one is RED. NO green/ground wire. One of the two wires must be the hot one. I could identify it with a tester.

My questions:

1. What kind of dimmer should I buy (single pole, capacity, etc.)
2. If the new dimmer should come with two different color wires and not just two black wires like the old one, which wire goes where (what should I test for, etc.)

This problem seems, by far, less complicated than the one about the GFCI replacemen for which I received your invaluable assistance but I do need to consult with you, the experts, about this smaller problem as well, even if some instructions should come with the new dimmer.

Thanks in advance.
Diana
 
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  #2  
Old 01-18-07, 09:59 AM
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You need a single pole dimmer, capable of handling at least 360 watts. 600 watts is a common rating for a dimmer, so you should be fine.

The dimmer will either have wires or screw terminals. On most dimmers, the terminals or wires are the same, and it makes no difference which is which. Connect the red wire to either terminal or wire, and the black wire to the other. The ground wire or terminal of the dimmer needs to be grounded to the ground wires in the box.

In case you need to know, the black wire is usually the always hot wire and the red wire is usually the switched hot. You can verify this using a tester. One side of the tester get connected to neutral wire or to the metal box, assuming the metal box is properly grounded.
 
  #3  
Old 01-18-07, 10:19 AM
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Thanks, Racraft!

I am on my way to buy the dimmer. Thanks also for the explanation about color coded wires and what they mean. I knew that the dimmer had to meet or exceed the wattage for which it's intended. I am glad to learn, through you, that they make 600 watts dimmers.

Thanks again.
 
  #4  
Old 01-18-07, 10:55 AM
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Just to add dimmers come in all kinds of styles so if you dont like the rotary round knob type there are many others to choose from. They wire the same and single poles are the easiest. One thing to watch out for is the size of the body on the dimmer they can get rather large in some styles and wont fit your electrical box (single device box) without crowding things. I prefer the dimmers that have wires and not screw terminals. This reduces the chance of any hot connections touching the metal box and shorting out. Screw terminal dimmers are getting rather rare so I doubt you will find one.
If you have a small voltage cordless screw driver this helps speed the installation up a bit when removing the mounting screws.

Remember to turn the breaker off I dont want you to have a bad hair day. Like......

http://www.greenmanspage.com/guides/shock.jpg

Roger
 
  #5  
Old 01-18-07, 12:07 PM
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Smile

Originally Posted by Roger View Post
Just to add dimmers come in all kinds of styles so if you dont like the rotary round knob type there are many others to choose from. They wire the same and single poles are the easiest. One thing to watch out for is the size of the body on the dimmer they can get rather large in some styles and wont fit your electrical box (single device box) without crowding things. I prefer the dimmers that have wires and not screw terminals. This reduces the chance of any hot connections touching the metal box and shorting out. Screw terminal dimmers are getting rather rare so I doubt you will find one.
If you have a small voltage cordless screw driver this helps speed the installation up a bit when removing the mounting screws.

Remember to turn the breaker off I dont want you to have a bad hair day. Like......

http://www.greenmanspage.com/guides/shock.jpg

Roger
Very funny, Roger! I would have ended up like the girl in the cartoon were not for the help of the experts here. Curly hair at the very least.

I watched carefully for the dimmer's size as per your advice and I decided to buy an exact replacement, rotary round know and all (you are right, the dimmers with screws on have become extint and they have been replaced by the ones with wires sticking out)

A final question: the old dimmer had black wires coming out from TWO separate orifices and NO green (ground) wire. The new one has the two black wires coming from the same orifice and a green one from another, opposite side. The box is metal and has NO bare or green wires to connect the green wirw. What do I do - connect the green wire to the metal box by means of a screw that could fit in some of the several holes that are there OR place a nut on the green wire, tuck it inside and consider the installation finished? The box is metal, NO plastic.

Thanks,
Diana
 
  #6  
Old 01-18-07, 12:16 PM
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To be safe and to be to code you need to connect the green wire to the metal box. There will be a threaded hole in the back of the box that accepts a green ground screw. The big box stores sell these screws in the electrical department. You can buy them as just screws, or as a screw with an attached green pigtail.

Sorry if this means another trip to the store...

If you don't have a ground screw avvailable just now, you can still make connections and test everything if you wish. Just don't install the dimmer or push anything into the box until you ground the green wire.

As for where the black wires come out, that does not matter. Just because they come out of the same place on the dimmer does not mean they are the same.
 
  #7  
Old 01-18-07, 02:02 PM
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Thanks and good-bye for now, Racraft.

I bought a few of those green, ground screws. The switch box is shallow so I had no trouble fitting the screw in the threaded hole at the back of it, with the green wire's terminal wrapped around it. So, now I am up to code and pretty soon I will inspect all the receptacles where a green/ground wire is warranted and I will make sure to implement that simple but important safety measure whenever missing.

The new dimmer is working nicely.

My gratitude towards you and towards all and everyone who helped me in this forum is enormous. Say hello to Roger for me and tell him not to become a couch potato and not to get "rusty" now that he is on retirement. :-)

Be well.
Diana
 
  #8  
Old 01-18-07, 02:12 PM
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Diana,

I would not open boxes just to check them. Old switches did not have ground screws, so you would have no place to connect a ground.

However, if you do open boxes, you will get more mileage out of moving back stabbed connections to screw terminals than you will out of grounding switches.

My advice: If you open a box for some reason, move any back stabs to screw terminals and ground the device if it has a green ground screw. If you have time and want to do this, then by all means do so, but I wouldn't put time into it that might be better spent elsewhere on more serious problems.
 
  #9  
Old 01-19-07, 03:17 PM
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Thanks for the tips, Racraft.

I never liked the "back-stab" method of connecting wires.

Your advice is truly appreciated.
 
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