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Hi all. Firstly, awesome site - learning so much, thank you all!!!!

Mid-80's custom home in Florida. Changing out to some smart switches. Seems no ground in box, best I can tell? Was reading elsewhere here that it's possible box itself is grounded? I wasn't clear on how to check this? Appears to be metal box. If it IS grounded, what do I do with ground wire on new switch? Thanks again.

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The box is grounded via conduit

The locknut on the right of your second photo along with the lack of ground wires and the doubled white wire running into the right-hand locknut all combine to say one thing: this is a conduit job, and since the box is metal and no ground wire is present, the conduit must be metal as well to provide the grounding path.

As a result, NEC 404.9(B) point 1 applies, rendering the switch yokes grounded:

(B) Grounding. Snap switches, including dimmer and similar control switches, shall be connected to an equipment grounding conductor and shall provide a means to connect metal faceplates to the equipment grounding conductor, whether or not a metal faceplate is installed. Metal faceplates shall be grounded. Snap switches shall be considered to be part of an effective ground-fault current path if either of the following conditions is met:

(1) The switch is mounted with metal screws to a metal box or metal cover that is connected to an equipment grounding conductor or to a nonmetallic box with integral means for connecting to an equipment grounding conductor.

(2) An equipment grounding conductor or equipment bonding jumper is connected to an equipment grounding termination of the snap switch.

If your new switch provides a ground wire...

If your new switch has a ground wire on it, that can be terminated to a 10-32 machine screw threaded into the mating hole on the back of the box. (It's visible top right in the second photo, just to the left of a larger hole.)

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  • So that sounds good then, right? Do I need to even connect a ground supplied with the switch? If so, to where? – Steve Nov 27 '18 at 4:58
  • @Steve -- does the new switch have a metal yoke? – ThreePhaseEel Nov 27 '18 at 5:06

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