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I need to replace a switch that controls a single light source in a bathroom.

The switch has two wires connected to it. I bought a replacement switch that has two screws (one for each wire), and a green ground screw.

Is it OK to connect just the two wires to the new switch and have the green ground screw unconnected?

This is not a remodel. Just trying to replace a switch that's broken.

EDIT: strangely, I didn't see a ground screw on the original switch. Was this permissable at some time?

EDIT 2: Picture as requested. The left switch is for a light source and is the broken one. Right switch is for a fan. The two switches are on the same circuit. The outlet is on a separate circuit.

I can't tell if the box is metal. It seems plastic but could be painted metal I suppose.

Broken switch

EDIT 3: With switches and outlet pulled out.

Switch and Outlet Connections

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Is the wire coming to the light switch encased in metal? –  The Evil Greebo Dec 7 '12 at 20:28
    
@TheEvilGreebo it looks like the wires inside of romex. 14 gauge with plastic insulation –  jglouie Dec 7 '12 at 20:33
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From other comments, you've left out far too much detail to answer clearly. Please post a picture. –  The Evil Greebo Dec 7 '12 at 20:55
    
Pull the duplex outlet (on the right) out and check to see if it has a ground wire. –  The Evil Greebo Dec 7 '12 at 21:04
    
@TheEvilGreebo yes the outlet is grounded –  jglouie Dec 7 '12 at 21:18
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3 Answers 3

up vote 3 down vote accepted

Because you are replacing the switch, not installing a new switch, you can get away without a ground. You should install a nonconducting, noncombustible faceplate though.

NEC 2008
404.9 (B) Exception. Where no means exists within the snapswitch enclosure for connecting to the equipment grounding conductor or where the wiring method does not include or provide an equipment grounding conductor, a snap switch without a connection to an equipment grounding conductor shall be permitted for replacement purposes only. A snap switch wired under the provisions of this exception and located within reach of earth, grade, conducting floors, or other conducting surfaces shall be provided with a faceplate of nonconducting, noncombustible material or shall be protected by a ground-fault circuit interrupter.

If you were installing a new switch, you would be required to provide an equipment grounding conductor at the outlet. And the switch would have to be properly grounded, in accordance with the National Electrical Code (NEC).

There was a time when an equipment grounding conductor was not required at each outlet, so it's fairly common to come across this situation (especially when working in older homes). You'll often see exceptions like this written into codes, so as not to require a full rewire just to replace a switch.

New info, Better answer

If you are replacing a switch a ground is not required, as per the above exception. However, if you're installing a switch; replacement or otherwise, into a metal box that is grounded. The switch will be ground via the devices yoke and mounting screws. So if the metal box is grounded, the switch is also grounded.

If the box is nonmetallic, and there are other grounded devices within the same enclosure. You can ground the new switch using a jumper between the switches grounding screw, and the other devices grounding screw. Just keep in mind, that you can't terminate two conductors under a single screw terminal. So if you do this, you'll have to use pigtails to make the connection between the devices.

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There's an outlet in the same box that should (I hope??) have a ground wire. It is on a separate circuit though. It sounds like the exception wouldn't apply in this case then because a ground wire wound be in the enclosure. Is that correct? –  jglouie Dec 7 '12 at 20:43
    
@LemonBeagle Is it a grounded receptacle (3 prong), or ungrounded (2 prong)? If the receptacle was installed at the same time as the switch, it may not have a ground. –  Tester101 Dec 7 '12 at 20:46
    
If it is grounded, is it up to code to use the ground from the other circuit to link in his light switch? –  The Evil Greebo Dec 7 '12 at 20:46
    
It's a 3 prong outlet, although it is a separate circuit (had to turn off a different breaker). –  jglouie Dec 7 '12 at 20:48
    
@LemonBeagle Does it have a grounding conductor connected to it? Is it a metal box? –  Tester101 Dec 7 '12 at 20:49
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Ok, now that we've got all the questions answered.

Get yerself a spare bit of unshielded 14ga copper wire.

Connect the ground screw from the new switch to the ground terminal on the grounded outlet.

You're grounded.

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Since it is in a bath you might want to consider installing a GFI outlet while everything is out –  mikes Dec 7 '12 at 21:48
    
Good advice - only if it's not already chained to an existing GFCI though. –  The Evil Greebo Dec 8 '12 at 1:33
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from the photo, the outlet clearly has a ground and should be spliced and then the ground run to each switch and the original outlet.

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