My house was built in 1979.

Today I replaced these 2 lights switches.

The left switch was a simple switch. The right one was a 3-way switch (i.e. there is another switch that also controls the same ceiling light).

Original wiring

original wiring

My diagram of the original wiring

It shows:

  • 3 bundles of wires coming from the top of the wall box and 1 from the bottom-left.
  • The circles are screw nut caps
  • Blue lines represent white wires (I assume "neutral")
  • 2 loose red wires (which were connected to the right switch)
  • 2 loose black wires (which were connected to the left switch)
  • 2 loose green (copper) wires (each switch was connected to 1)
  • 1 loose white wire (which was connected to the right switch)


Is what I did here safe and up to code?

2 mins: https://photos.app.goo.gl/BZxXbzoxf8EXxTsi6

Secondary questions out of curiosity

  • Why are ground wires from all 4 bundles clumped together (shown at 0:32)? Is it ok that they don't have a screw nut?
  • I'm a complete newbie. I would have assumed that the left and right switches would have nothing to do with each other. Yet there is mixing of wires from the 4 bundles (instead of there being 2 totally separate pairs of bundles). What am I misunderstanding?

Here is the final result, which works:


  • 1
    If they are on the same breaker, it is okay to connect the neutrals together. The white wire on the switch should be marked as not a neutral
    – crip659
    Jan 6 at 21:55
  • @crip659 Thanks for your response!
    – Ryan
    Jan 7 at 1:07


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