macl-153m without ground

I just bought a macl-153m to replace a very old lumitron rotary dimmer that died. After removing the old dimmer, I checked the wiring in the wall box and found the bare ground wire, coming out of the romex, is not connected to ground. My question is, since the old dimmer worked for about twenty years, can I connect the macl-153m without connecting the ground wire?Thanks,henrylr

If you don't have a ground, the code states that you must use a nonmetallic wallplate without metallic screws. That requirement would be satisfied by a Claro screwless wallplate. The Maestro will operate correctly without a ground.

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If there is a ground wire that isn't grounded you should really find out why.