House is 80 years old. 2 black wires in switch box and no ground. Trying to replace single pole light switch with motion sensor light switch that works with incandescent,LED, and florecent bulbs. Currently using LED bulbs.

Problem: The GE motion sensor switch has 4 wires. Red (load), black (hot), white (neutral)' and green ground. The instructions give no information on how to connect the four wires on the sensor to the 2 in the light switch box.

  • 3
    You will need to run additional wire to have this device work. Such is the joy of 80 year old wiring.
    – Ecnerwal
    May 19, 2016 at 15:07
  • @Ecnerwal any basic light switch works on 2 wires only. The other ones, even when present, are just passing through. At some point in time, it made sense to route the other wires more directly and not through all the switches
    – njzk2
    May 19, 2016 at 16:23
  • Google "occupancy sensor no neutral" there are many choices.
    – Tyson
    May 19, 2016 at 16:23
  • However those don't play nice with LED lighting. You would need to have at least one bulb be incandescent. May 20, 2016 at 17:58

1 Answer 1


If the switch box ONLY has the two black wires in it, then its just a switch leg, with the main wiring run in the ceiling above the light fixture. Without additional wiring installing this device in this location may not be possible.

  • Oh my...that's what I was afraid of. I like to tinker, but I think that is something better left to the professionals. Thank you though.
    – Patricia
    May 19, 2016 at 15:10
  • Note that they do make motion sensing switches (occupancy sensors) that do not require a neutral or ground. They usually only work with incandescent bulbs.
    – JPhi1618
    May 19, 2016 at 15:26
  • 1
    @Patricia most "smart" switches require a neutral. A simple "dumb" mechanical switch does not. Basically, any 125V device that uses electricity requires a neutral in order to provide a return path for electricity it uses. A smart switch is more than a simple mechanical interrupt, it uses electricity. Therefore, it requires a neutral. Eighty years ago the idea of a smart switch did not exist, so neutrals were not run to switch boxes unless the switch box was between the breaker and the light. Switches were not grounded back then, either. Modern wiring requires both ground and neutral.
    – user4302
    May 19, 2016 at 15:49
  • 2
    Bit of trivia: The 2011 NEC code addressed this issue for new installations by requiring neutral conductors in all switch locations. See 404.2(C) NEC 2011.
    – mfarver
    May 19, 2016 at 16:50

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