Burning plastic smell after replacing switch


  #1  
Old 12-14-04, 09:04 AM
Nate7zulu
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Burning plastic smell after replacing switch

We were painting the bathroom this weekend and decided to replace some lights around the mirror and a switch that worked half the time. This is my first time doing anything electrical more complicated than replacing an outlet. After replacing the switch over the past few days I have noticed a smell like burning plastic in the bathroom. My wife told me I'm being paranoid because I don't trust myself with electrical work.

Now this morning even she smells it. I'm 90% sure it's coming from the switch. Before I left for work today I flipped the breaker to be safe.

Here's the story on the switch. Two actual switches. Top one controls the lights around the mirror (which I replaced this weekend). The bottom switch controls two things: the exhaust fan and the light above the shower. Prior to the work this weekend the bottom switch had to be wiggled to get the fan and shower light to stay on. I assumed it was a contact in the switch, went to the store and bought a switch that (on the outside) looked identical (2 horizontal switches on top of one another).

Now I assumed light switches were a lot like outlets. You had 3 or so wires and you just matched them up to seperate (and the corresponding) contact screws.

I pulled out the old switch and to my surprise, the above scenario wasn't the case. First, all the wires were all black. I figured that the one on the left (facing the switch) was the main current. The one on the upper right was the lights around the mirror. But there were 2 wires connected to the same contact screw on the lower right. The switch only had 4 contact screws, 2 on each side and the black screw on the lower left had no wires attached. Okay. I have seen some odd things in the house and with my complete inexperience with electrical work, maybe this was the norm.

When I pulled the new switch out I right away noticed that the new one had a green ground wire coming out the back of the switch. I has no place toi attach it to inside the box. So I put a cap on it and taped it up. My new switch has 2 contact screws on the left but 3 on the right. I hooked the upper left and upper right wires up as the old one had been. But I decided to give each of the lower wires their own contact screw. Of course when I turned it on then I noticed either way you flipped the bottom switch, either the fan or the shower light would come on. We can't have that. So I rewired the bottom two wires to the same contact screw as the old switch had been.

And ever since I'm getting this smell of burning plastic and I'm feeling nervous.

Here's a bit of additional info:
- The plate always stuck out from the wall so when I hooked everything back up I put some sealant around the plate to make it look nicer.
- When trying to get the wires onto the contact I marked up the copper pretty bad on 2 of them. I also torn away some of the rubber coating in places on the wire. I put tape around those places (and I think I got all of them)
- The box is pretty far recessed into the wall and the wires were short. I didn't have a whole lot of room to work.
- There were some white wires in the back but nothing connected to the switch. I figured I'd be fine as long as I just connected the switch wires just like the old one had been.

So I'm very anxious to see if you guys can help me here. What's going on? Do I need to call in an electrician? Thank you!
 
  #2  
Old 12-14-04, 09:18 AM
J
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Now I assumed light switches were a lot like outlets. You had 3 or so wires and you just matched them up to seperate (and the corresponding) contact screws
This is a very bad assumption. Switches are wired nothing like receptacles.

When trying to get the wires onto the contact I marked up the copper pretty bad on 2 of them. I also torn away some of the rubber coating in places on the wire. I put tape around those places (and I think I got all of them)
This is very bad. If an electrician made these mistakes, he'd rip all the wiring out and start over.

And ever since I'm getting this smell of burning plastic and I'm feeling nervous.
You made lots of mistakes, and I would encourage you not to do any more electrical work until you improve your skills. Read books, attend classes, ask questions. Nevertheless, I think your burning smell is probably coming from the effect of heat on the chemicals used in the manufacture of the new fixtures. Monitor it closely. If the smell doesn't go away within two weeks, call and electrician to fix your work.
 
  #3  
Old 12-14-04, 10:23 AM
Nate7zulu
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Originally Posted by John Nelson
This is a very bad assumption. Switches are wired nothing like receptacles.
I see that. Now.

Originally Posted by John Nelson
Nevertheless, I think your burning smell is probably coming from the effect of heat on the chemicals used in the manufacture of the new fixtures. Monitor it closely. If the smell doesn't go away within two weeks, call and electrician to fix your work.
So this isn't anything to worry about in the immediate term? Is it a common occurence? When you say fixtures, you're speaking of the new switch?

As for the green grounding wire, there is no danger in simply capping it and taping it off if there is nothing to attach it to?

Thanks for the response.
 
  #4  
Old 12-14-04, 10:30 AM
J
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Are the switch(es) the only thing you replaced? You didn't replace any light fixtures? If so, then I think you should be worried because my previous explanation would not apply in that case. Shut off the breaker, pull out the switches and look for scortch marks on the switch or any of the wires. I think you may indeed have a dangerous situation caused by your poor workmanship. All damaged insulation and nicked wires must be replaced. You might want to seek some experienced help.

If the box is metal or if there are any grounding wires in the box, you should attach your grounding wires there. Otherwise you have no choice but to cap off the green wire.

Exactly what kind of new switch did you install? Most ordinary switches don't have wires coming out of them.
 
  #5  
Old 12-14-04, 10:57 AM
Nate7zulu
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Originally Posted by John Nelson
Are the switch(es) the only thing you replaced? You didn't replace any light fixtures?
I did replace fixtures but they're on the other side of the room. The smell is strongest near the light switch that I replaced.


Originally Posted by John Nelson
Exactly what kind of new switch did you install? Most ordinary switches don't have wires coming out of them.
I'm not positive on the type. The display model and picture on the box looked idetical to the one I had. It was only when I got it home and out of the box that I noticed it had a green grounding wire coming out the back.
 
 

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