Replacing switch causes short at breaker

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Old 03-25-19, 01:44 PM
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Replacing switch causes short at breaker

I'm replacing a dimmer switch in a 3 switch box - the housing on the new switch is larger than the old switch and when I screw it into place and turn the breaker back on, it makes the breaker pop. Before the switch is "screwed into place" all 3 switches are working. I think the issue is that because the housing on the new dimmer switch is larger/deeper than the previous switch, it must be crowding the box too much and causing the short - can anyone verify this for me?
 
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Old 03-25-19, 01:50 PM
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If a hot terminal is touching a ground wire it will trip the breaker. Put a wrap of electrical tape around the switch body to cover any bare contacts and see if that fixes the problem. Or wrap the adjacent switch.
 
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Old 03-25-19, 02:29 PM
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A common problem is that the wires get pushed to the back of the box and the hot wire hits one on the cable clamps. If it's older wiring and brittle..... the insulation could be compromised where it enters the box.
 
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Old 03-25-19, 02:31 PM
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If you have a metal junction box, check if there is any wire pushed against sharp edges.
When wire gets pushed against sharp edges inside of a metal junction box, it can cut through the insulation and cause a short to ground.
If you find any, tape damaged insulation and bend wire inside to avoid pushing the wire against sharp edges.
 
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Old 03-25-19, 03:46 PM
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I did check the wires, and while they are older, the insulation does appear intact. And as I said I checked my connections before I screwed the dimmer switch down.and all worked.
I actually had to pull out one of the other switches to get to the wires behind it and I did tape it before I put it back in place. The third switch was already taped, I guess I'll pull the whole thing apart again and see if there is something I missed.

 
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Old 03-25-19, 04:17 PM
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If your not able to get it to work I would replace the box with a deeper one. Before unhooking anything turn off the breaker for that circuit. Label each conductor and cable in the box then take some pictures of the wiring so you can see where everything goes and hook is all back up.
 
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