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I have a two-gang box that I'm planning to install new Lutron smart switches in. Currently all of the neutral (white) wires coming into the box are connected together. But one Ground wire is also connected to whites.

Questions:

  • Why the ground wire could be connected to white ones?
  • Is it safe or should I disconnect ground from there? (blue arrow)
  • Should I disconnect ground from white wires to install the new switch?

The Lutron wireless switch requires 4 wires: 2 hot wires, 1 ground and 1 neutral.

Schema photo

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    In my opinion you got a broken wire somewhere and they used the PE as neutral to avoid replacing. That's why american wiring sucks: no conduits makes mainenance a hell hence bringing to this kind of "solutions".
    – DDS
    Commented Feb 10, 2022 at 10:50
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    Got it. Let me disconnect the wire and check the whole breaker circuit
    – CuriousVit
    Commented Feb 10, 2022 at 14:16

2 Answers 2

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It shouldn't be that way. The catch is that there are two reasons why it is that way:

  • Misunderstanding of Neutral vs. Ground

Neutral and ground are connected together in one place, normally in the main breaker panel. But because they are connected in that one place, and because a test in a properly functioning electrical system will show that connection between neutral and ground anywhere in the house, and because there are other historical situations (3-wire dryer connections) where neutral and ground have been connected, some people assume that it is OK to connect them together, possibly even thinking it is helpful to connect them together. If that is the reason for this connection, disconnect it and you will slightly improve safety with no downside.

  • Cheating

This can take the form of using ground instead of neutral or neutral instead of ground for a bunch of reasons. For some of those reasons, disconnecting the wire will have no ill effect. However, if the reason was to work around a broken neutral then you will find something no longer working properly.

If you end up finding something not working properly after disconnecting the wire, you will have to carefully check each part of the circuit (everything powered by the same breaker) to figure out where the problem is and determine how to fix it.

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    Thank you. I'll disconnect the ground wire and check everything powered by the breaker. I have a lot on that breaker: 6 lights and 5 outlets
    – CuriousVit
    Commented Feb 10, 2022 at 14:15
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Totally depends on age of house and line supply. Some houses have just two black wires coming in, 240 volts, and use a ground rod for neutral. Others have a white neutral wire coming in, so black to white is 120 volts. And, there are older houses that have messy wiring with grounds and neutrals joined, broken, or sometimes wired to code. Bottom line: you need a 120 volt black wire, and a solid ground or neutral (white or bare) to get power. If the grounds are good, shock hazard is low. Tearing apart walls to replace wiring is very expensive.

I don't know why we can't have just two wires rather than three, with the neutral side grounded. It works and some countries are fine with that (though many have 240 volts instead of 120). But code writers have other ideas. With the wide and narrow plug prongs now almost universally used in America, the danger of voltage on a metal cabinet or component is much lower than it used to be over half a century ago.

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    This is wrong on so many levels! use a ground rod for neutral - wrong A) a ground "rod" is a specific application for whole house grounding B) using ground for neutral defeats the purpose of grounding. older houses that have messy wiring and that mess SHOULD be fixed. a solid ground or neutral (white or bare) to get power - wrong. 120V in the US needs a neutral (white or grey insulation, NEVER bare) and a ground for safety. If the grounds are good, shock hazard is low is exactly why we have 3-wire 120V circuitry, which you go on to question in your next paragraph.
    – FreeMan
    Commented Oct 7, 2022 at 13:18

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