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An electrical novice, here, with some basic understanding.

I’m installing several smart switches around the house, where most locations require a 3-pole switch. I’ve had no trouble installing at these locations.

There’s one single-pole switch for an outside flood light I’d like to install a smart switch for, but I’m super confused.

As I understand, a standard single-pole switch in the “middle” of the house will have three wire bundles that intersect:

  1. Upstream power bundle (hot, neutral, ground)
  2. Downstream power bundle to carry electricity to the remainder of the house.
  3. A bundle that branches off the upstream power to carry electricity to the light itself.

Right?

The switch I’m dealing with seems to be the “end of the line”, as it were, but there is only a single wire bundle (single hot/black, single neutral/white, single ground/naked). See pictureExisting wiring

Questions:

  1. How is this switch able to power the light? I’d expect there to be two wire bundles (upstream power bundle and a bundle going to the light), but there is definitely only one. What am I missing?
  2. Ultimately, I want to connect this 3-pole smart switch that requires a neutral wire, but it doesn’t seem to be working. The switch itself powers on (blinking light), but the outside light will not turn on. How should I connect the wires if there’s only one wire bundle? See diagram from manufacturer for instructions.

Switch wiring Manufacturer’s suggested wiring

Really appreciate your help!

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    When there is only one cable, bet that it's a switch loop. Which, unless the cable has a third insulated conductor, means no neutral, which means few smart switches will work there.
    – keshlam
    Aug 21, 2023 at 0:43
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    I agree with @keshlam, this appears to be a switch loop that will not have the required neutral to supply the smart switch with power. I'd be surprised if the instructions did not warn against this, perhaps that is on the next page?
    – MacGuffin
    Aug 21, 2023 at 0:49
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    As the others have said, this is a switch loop. Which means white is not neutral. (Neutral is always white, white is not always neutral). One wire is "always hot" (a.k.a., "Line") (should be white, but no guarantee) and the other is "switched hot" (a.k.a., "Load"). Separate the wires and then (carefully) turn on the breaker and you can use a tester to figure out which wire is which. But the bottom line is: You need to either redo the cabling (to get neutral to this box) or get a smart switch that doesn't require neutral (but which gets tricky, some of those don't work well with LEDs). Aug 21, 2023 at 1:12
  • Super helpf, thank you! I had wondered (assumed) something like that was possible, but couldn’t reconcile where the power was coming from. Seems like I should be able to convert this to a true single pole easily, yeah? i.e., run a wire bundle from a nearby socket to this switch as the power source, then treat the existing bundle as the downstream power to the fixture. Then I’d need to reconfigure the wiring at the fixture itself, yeah? Aug 21, 2023 at 2:06
  • Follow up question: seems the key to the switch loop idea is that the power source is already at the fixture. So, I could either do what I described in previous comment (and not use the power already at the fixture, or I could try to find where the power going to the fixture is coming from and place a new switch at that location. Do you agree? Does one seem preferable? Aug 21, 2023 at 2:28

1 Answer 1

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I appreciate the help from others who told me about switch loops. I didn't know those existed.

To provide a formal answer, and some additional details that might help someone else, it was indeed a switch loop--with some variation.

I intended to turn the switch into a conventional format so I could install a smart switch that requires the neutral wire. When I climbed up to the floodlights to undo the switch loop, I was again surprised to find only one bundle of wires, where I expected to find two, per the standard setup for a switch loop (see image below)Flood light wiring.

Took me a bit to think through how this could possibly work. I realized that the switch loop (wiring switch?) from black to white must be happening at another light switch between the light switch in the basement and the floodlights. There was another set of light switches in the kitchen directly above the light switch in the basement and that's where I found the switch loop (wiring switch?).

Turns out, the kitchen was exactly the ideal place for the light switch for the floodlights, so I disconnected the switch in the basement entirely and installed a new light switch in the kitchen.

To avoid having to replace the two-gang electrical box with a three-gang, I replaced the single light switch with one that has two independent switches within a single unit (example image below). double switch

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  • The sharp metal edges where they could touch live wires don't look "kosher" to me. You might need to have an electrician look at that.
    – MacGuffin
    Sep 6, 2023 at 19:35
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    I still think you're using technical words you don't fully know the meaning of. If you want actual help, stop doing that and use plain language for things. But then given that your'e answering your own question, I wonder lol. Regardless, make sure you follow electrical codes. Sep 6, 2023 at 20:16
  • @Harper-ReinstateMonica: I appreciate the feedback and welcome any corrections/suggestions to my post. I tried asking clarifying questions to my original post but didn't receive answers, so I looked into switch loops and did my best. I was just trying to share that the actual wiring switch (from black to white) in a switch loop does not have to happen at the light itself, which is what I expected from online diagrams. Sep 7, 2023 at 20:10
  • @MacGuffin: Thanks for the feedback. I thought the previous owners told me an electrician did the work for this light, but maybe they did it themselves. When you refer to "metal edges", are you referring to the soffit? The wiring is housed in a standard electrical box above the wire, and unless I'm misremembering, the soffit is plastic. What do I need to fix? Sep 7, 2023 at 20:16
  • Nothing should be poking into the electrical boxes but the wires and connectors. The soffit edges may be plastic but that isn't how things should be done. If an electrician and building inspector signed off on it then I guess I just got vetoed. If you can live with it then so cant I.
    – MacGuffin
    Sep 8, 2023 at 4:21

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