Odd wiring setup in light switch

Question

Hoping for some help after trying to get this setup to work. I’ve purchased a smart switch that requires two load wires, one neutral wire, and one ground wire.

When I took out my existing light switch I found it having the two load wires but also two neutral (white wires) connected to a ground wire (green). I unwrapped all the wires and hooked it into the smart switch but it didn’t work.

After some investigation it seems that the green wire must be touching one of the white wires for even the normal switch to work. Does anyone have any idea what’s going on here and what the right setup should be?

What’s very odd is that my white wires must be connected to green ones. If they are disconnected the switch doesn’t work.

Thank you.

Here is a wiring that does seem to work (note the white and green are touching):

The following wiring doesn’t work (white and green not touching):

UPDATES:

Thank you all for the advice and help, it works great:

Answer 1

Someone ran out of white wire

It appears the previous installers ran out of white wire to use for running neutrals, so they grabbed the spool of green wire off the back of the truck to keep the job going. As a result, you'll need to treat the green wires in your switch boxes as neutrals for the purposes of installing your smart switch. This is workable here because you're in Chicago, land of metal conduit everywhere, and metal conduit is usable as a grounding path all by itself.

So, what I'd do is wire up the line/load pigtails to the wires that went to the switch, attach the white pigtail to the existing bundle of white/green wires (making sure they're bundled together as before), mark the green wire as a neutral with white electrical tape (given that replacing it isn't an option at this time), and either leave the green pigtail capped off/unhooked (grounding the switch via its yoke) or terminate the green pigtail from the switch on a green 10-32 ground screw in the matching hole in the back of the switch box (grounding the switch to the box via its pigtail). If there are any other bundles of wires in the box (such as the bundle of reds in the first switch box), just leave them intact.

Answer 2

As you know, "green = ground" and "white = neutral". As you probably also know, ground and neutral should only be connected in one place (main panel) and not in individual switches or other devices. So that means one of two things:

Broken Neutral

This is the classic situation. A neutral breaks. Instead of running a new neutral wire or a new cable, someone figures "ground and neutral are connected so I can just run my neutral over ground". It works but it isn't safe.

Wrong Colors

You wires are in conduit. I know that for two reasons:

• You have orange wires. Standard cables are almost entirely black, white, green (though usually bare for ground) and red. But not orange.
• Your profile shows you are in Chicago, which is conduit-land.

That is good news, because it means you can add or replace wires as needed. Not trivial, but unless things are really messed up, a lot easier than replacing cables inside walls.

From the look of some of your pictures, one of the switches has green & orange in one conduit and red & white in another. Green (= ground) should never be with one single wire - it should always be with at least two (hot + neutral or hot + switched hot). Plus if the conduit is metal then you may not even need a separate ground wire.

Which means either:

• An amateur who didn't check here on DIY SE first picked colors at random and used green for neutral (in which case it needs to be swapped for white or gray)
• Someone truly didn't understand that ground and neutral are different and just figured "white or gray or green for neutral/ground".

Either way, you need to figure out where the wires go and: * Add white or gray neutrals as needed * If separate ground wires are needed, add them where needed, otherwise remove the green wires.

Answer 3

Mark that green wire white

That green wire behaves at both ends like a neutral. I think it is one. I would get some white tape and spiral wrap it around that green wire, to mark it most of the visible length. Do that at both ends. This is still illegal, but if you don't happen to have a spool of white THHN wire in your kit, you are certainly better off for now, until the wire can be replaced properly. You would lash the proper white or gray wire to the green wire for about 8", then use it to pull the white wire in.

I have zero tolerance for mis-colored wires, especially in conduit where it's easy to always have the wire color match their purpose (as they did here with orange=switched hot).

Where to actually get ground

Get your actual ground from a screw hole in the back of the metal box, which should be tapped #10-32. They make #10-32 ground screws that are green, but any 10-32 screw will suffice.

This might be a 3-way circuit

Anytime you see 2 wires of the same (odd) color grouped, around switches, that is often the pair of travelers for a 3-way circuit. 3-way switches have 3 terminals, 2 brass 1 black. The switch in OP will not work on a 3-way.

Former multi-wire branch circuit

If you're wondering what's up with the blacks and reds tied together, that's probably a former multi-wire branch circuit, possibly for lighting. (lighting needs a lot less power than it used to). The reds and blacks can be tied, but they shouldn't be paralleled. I.E. the same red and black should not be tied together in more than one location.

Answer 4

CAUTION: The following requires verification:

• The white and green wires in the box (pigtailed to each other and not connected to anything else) appear to be your neutral - should be pigtailed together with the white (neutral) wire of the new switch.

• The red and orange wires in the box appear to be your live and load; the red is likely the load wire, the two orange wires are likely live (one powers the box, the other continues onward to power some other part of the circuit). The red wire should be pigtailed to one of the black wires of the new switch, and the two orange wires should be pigtailed to the other black wire of the new switch. Does not matter which black wire is assigned which role (live vs load).

• There is no ground in evidence; if you can't reliably identify a ground connection, you should not install the new switch; the green wire of the new switch must be connected to a proper ground. The box itself might be usable, provided there is a reliable electrical path from the box to "ground".