Struggling with switch wiring

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  #1  
Old 11-09-04, 05:08 AM
ddesaute
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Struggling with switch wiring

We recently replaced a light fixture in our dining room and are having problems with the dimmer switch. There was an existing incandescent light fixture w/ dimmer switch that worked without issue. I'll try to keep a long story short but we attempted (without success) to install a low voltage light system with appropriate low voltage dimmer. When this didn't work out, we returned the light and purchased a new incandescent fixture. Installed it without issue. We're running into problems with reinstalling the old dimmer switch. Unfortunately, we didn't take note of how it was hooked up before. This is what we have in the junction box on the wall -- two black wires (one marked with electrical tape), two white wires twisted together, a ground wire, and one red wire. We were told the red wire is there for a ceiling fan and we don't have to use it. We attempted to hook up the switch in the obvious way -- black wires to black wires (there are two lead wires off the switch), ground to ground and did nothing with the white neutrals. The light works but the switch does nothing other than completing the circuit - it does not control the light.

This seems like a very simple problem but we've tried every conceiveable combination was can come up with and the switch just doesn't work.

Can anyone provide any advice? We've installed switches in the past without issue but this one has us stumped.

Thanks in advance,
Deb D.
 
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  #2  
Old 11-09-04, 05:28 AM
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Why don't you start by describing thwe wiring at the ceiling box, as it attaches to the light and to any other wires that may be there.

Does the dimmer switch do anything at all?
 

Last edited by racraft; 11-09-04 at 05:40 AM.
  #3  
Old 11-09-04, 05:43 AM
ddesaute
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In the ceiling box, there is a black wire, a white wire and a ground wire. The light fixture has two black wires and a ground.
 
  #4  
Old 11-09-04, 06:10 AM
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Although it may be obvious, how are those wires connected, and what happened to the red wire?
 
  #5  
Old 11-09-04, 06:46 AM
ddesaute
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The light fixture has two black wires (with no noticeable difference between the two). One is connected to the white neutral in the ceiling box, one to the black. And the ground wires are connected together. If the red wire is in the ceiling box, it must be pushed all the way back because I don't even remember seeing it there.

This seems like is should be so simple - it's frustrating. I'm really starting to think the switch might just be bad. My plan is to pick up another one on the way home and see if I might just be over-analyzing the problem. The fact is that the light works fine - the switch just isn't controlling anything but seems to just be completing the circuit.
 
  #6  
Old 11-09-04, 07:26 AM
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To verify if the switch is bad, replace it with a simple (working ) regular on-off (toggle) switch.
 
  #7  
Old 11-09-04, 09:33 AM
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In the switch box, take the two black wires (one marked with electrical tape) and simply touch them together. The light should come on. That's all a light switch does - connect juice to the light fixture. Many people instinctively think that touching two live wires together is a short circuit. If you disconnect a receptacle, for instance, and touch the white and black wires together, that's a short. You'll of course get a big pop and a flash of light and the breaker or fuse should blow. That's not what's going on with a light switch. The "neutral", or white wire, comes from your electrical panel and goes through the switch box straight to the light fixture, where it is permanently connected. (Sometimes the neutral does not go through the switch box at all, but goes between your walls straight to the light fixture ceiling box. But from your description, yours passes through the switch box.) One of the blacks comes from your electrical panel to the switch box. Let's say that one is hanging there at the moment, not connected to a switch. The other black goes from the switch box up to the light fixture. Let's say it, too, is hanging out of the switch box not connected to the switch. The other end of this wire is connected to the light fixture. It is dead (no voltage) at the moment. All the light switch does is allow the power from your electrical panel to continue through the switch box up to the light fixture when you want the light on. You're right, all the switch does is complete the circuit. If you hold the two black wires by the insulation and touch them together, the lights should come on. That will tell you that your dimmer is bad. If the lights do not come on, the problem is with the way you hooked up the light fixture, or all the bulbs are bad. Probably niether of these things is what's going on. Chances of a new incancescent light fixture being defective are very slim. The only other thing at the fixture I can think of is possibly your black wire is broken inside the insulation and therefore is not visibly detected. Sometimes pulling the wires out of the ceiling box and stuffing them back up into it repeatedly will fatigue the wire and it could break. This is also rare, but possible.

The light fixture came with two blacks. (That is commonly done, although I personally would like to see a black and a white on all light fixtures.) Anyway, it doesn't matter which is which. One goes to the black wire that comes from the light switch to the ceiling box, and the other goes on the white neutral. Since you replaced an existing light fixture, I'm almost certain you disconnected one black wire and one white wire when you removed the old one. Installing the new one therefore should have been straight forward, and from your description it sounds like you easily did it correctly. So I suspect the switch at this point.

Hope that helps.

Juice
 
  #8  
Old 11-10-04, 04:59 AM
ddesaute
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Thanks to both of you for the info and advice - it was very helpful! As it turns out the swith was bad. Unfortunately, after replacing it a second, equally frustrating, problem came up. The switch now controls every light that's on that circuit. So we can turn the dining room light on and off (or dim it) but it also turns off lights (or dims them) in the kitchen, a bathroom and a bedroom along with it!

I think the biggest source of frustration is that this isn't a new set up. There was an old fixture and switch in place before we started this project and, other than cosmetics, nothing obvious has changed - it's a different fixture and switch, but from a wiring perspective they're identical.

Just thought I'd throw this out there in case you've ever heard of this happening. We've already talked to the help line for both the fixture and the switch, each of whom assured us we connected it properly. We're ready to seek professional help at this point (including possible therapy!).
 
  #9  
Old 11-10-04, 05:11 AM
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If the switch is controlling other portions of the circuit, then you have something wired wrong. In other words, you don't have the switch or the light wired in the same way as the previous setup.

Regardless of what you do, remove the dimmer switch right away, or turn it off. You don't know what else is also on the same circuit. You may very well have receptacles on the circuit. If you feed a receptacle from a dimmer switch, you run the risk of damaging whatever is plugged into the receptacle. A dimmer varies the voltage. This is fine for incandescent lights, but not good for other types of lights and not good for normal electrical devices.

My suspicion is that you need the red wire.

Tell us exactly what wires are in the switch box and what are in the ceiling box. Be very specific, and include all wires, regardless of what they are (or were) connected to. Include all wires, and all cables, and identify which wire comes from which cable, etc. Your problem is fairly easy to fix.

Now the lecture. Never ever disconnect a light, a switch, a receptacle, or any electrical device without making detailed drawings of how the wires are connected, and, if necessary, marking which wire is which.
 
  #10  
Old 11-10-04, 09:16 AM
ddesaute
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Trust me, the lecture is unnecessary -- from now on I'll mark everything, draw everything and take photos if I have to! We already removed the switch and just put in a plain toggle switch for now until we figure it out.

I'm going to describe this from memory but I'm sure it's accurate because we've been staring at this thing for days now. In the switch box there are two black wires and two white wires (one coming from the top and one coming from the bottom, relatively speaking), one red wire (which is capped off), and one ground wire. The two whites are connected together. In the ceiling box there is one black, one white, one red, and one ground wire. The red one is also capped off. The light fixture has a ground wire and two black wires. The black wires are connected from the light source and split at the end (looks like a plain electrical cord). One wire has printing on it, one doesn't. We have the ground wires connected, the black wire with printing going to the white neutral in the ceiling box and the plain black going to the black in the ceiling box. (I don't that there's even a difference between them but thought it was worth noting at this point.) At the switch box, we hooked the ground wires together and the two black leads from the switch to the two blacks in the box, left the red wires capped off at each end and the neutrals together in the switch box. This is as much as I can recall without standing in front of it. I can add more detail tonight if this doesn't seem to include everything but I don't think I missed anything.

Everyone we've talked to seems to think this is correct but obviously, it's not.
 
  #11  
Old 11-10-04, 10:03 AM
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Unless you aren't telling us all the wires in the box, there is more to the picture.

If the wires are as you described (and no more), then your wiring should not effect the rest of the circuit.

I am guessing either that you mis-wired something, or that the wiring does not go straight to the ceiling box from the switch box.

Please verify the wiring and post back. Also, indicate if the red wire at the switch box comes from the top or the bottom set of wires. To provide more detail, also tell us about the wiring at one of the other places on the circuit (one that goes out with the switch being off).

B the way, does the switch still shut off those other rooms, even with the toggle switch installed in place of the dimmer?
 
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