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This is related to my other question here.

I just learned of the "power through fixture" concept and it seems that WeMo dimmer switch isn't compatible with it.

I want to believe that what I have in my apartment is NOT power through fixture. But is there any way for me to check if it is?

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  • Do you have a link that explains what you mean by "power through fixture"?
    – JPhi1618
    Jan 16 '18 at 20:36
  • Also, what country are you in? I noticed your last question has a brown wire, so I'm thinking you're not in the US...
    – JPhi1618
    Jan 16 '18 at 20:42
  • that's when you need to use a tungsten bulb (or other medium-heavy load) to power a dimmer/lighted switch/motion detector/dusk-to-dawn and other power-needed "switches" that don't need a neutral. Since the Wemo needs a neutral, you can't parasitically power it like that, which is a good thing anyway: those devices have compat issues with lots of low-power bulbs.
    – dandavis
    Jan 16 '18 at 20:42
  • @JPhi1618 Soutern Ontario in Canada. The power through fixture from what I understand is this: howtowirealightswitch.com/wp-content/uploads/2014/09/…
    – Metal Wing
    Jan 16 '18 at 20:51
  • 1
    oh, and if you have a wemo working, you must have a neutral to be powering it...
    – dandavis
    Jan 16 '18 at 21:13
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Actually, the thing you're referring to is called a switch loop.

You can find out if you have a switch loop by opening up the switch, pop off hte cover plate and pull the switch out a bit.

If you see one cable coming into the box with two wires (white and black), and both go to the switch itself (as well as ground if present), that is a switch loop.

If you see one cable, but it has black, white and red wires -- and black and red go to the switch and white is capped off and connected to nothing -- that is also a switch loop, however it complies with current code, and that white wire is the neutral wire the smart switch is looking for.

If you see one cable with black-white-red, and all three go to the switch, see "3-way switches" below.

If you see two cables coming into the box, and the whites from each cable are wire-nutted or spliced to each other in the back of the box... and one wire from each cable goes to the switch (aside from grounds)... that is power at the switch. That configuration is friendly to the use of smart switches. The white wires bundled together are the neutral, and they are not "spare", they are in-use as part of the circuit. The smart switch's neutral can be added to these.


If you see three wires (other than ground) going to 3-4 different terminals on the switch, and 1-2 of those terminal screws are black... that's a different thing, that's a 3-way switch. That is more complicated. But as far as smart switches, you have more options if you have that nice 3-way cable with its red wire.

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