Connecting to Smart Switch - Existing has 3 Black Wires, No Ground

Old 10-17-22, 10:07 AM
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Connecting to Smart Switch - Existing has 3 Black Wires, No Ground

Hi All, I am trying to replace an existing single pole light switch with a smart switch.

The existing switch has 3 black wires going into it (2 back stubbed) and one to the screw on the side. I assume one top back stub (A) is live. The adjacenct screwed black wire (B) carries live to other switches in the room. And the bottom backstab is the lout wire (takes power when switch is turned on).
and a bunch of white wires are bundled together in the box.

The new smart switch (Meross MSS510) has 4 wires. Live lout neutral and ground.

Questions :
a) How do I make the connections?
b) Can I combine the 2 black wires (A and B) and the live from the smart switch with a single cap?
c) As there is no ground wire, can I leave the ground in new switch empty?

Thanks in advance.


Last edited by Abhijit; 10-17-22 at 10:19 AM. Reason: Incomplete details
Old 10-17-22, 02:41 PM
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b, Yes, combine the two blacks with the line in.
c. There has to be ground in there somewhere. Since the box is metal connect the switch ground to one of the ground screws in the bottom of the box.
Old 10-17-22, 05:06 PM
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You described the connections correctly yet you connected the smart switch green ground wire to a black wire.

I can see a bare ground in the back of the box that you should be able to attach to.

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