I am trying to install a smart flood light that requires a neutral wire. Edit after initial post -> Using a multimeter, when the switch is turned on, the outside black wire reads 120v and the white 0. Both outside wires are 0 when the switch is turned off. (not sure if that means a neutral or not...)

The wiring for the current porch light has a black, white, and ground wire. outside

However, the switch that turns the light on has 2 black wires. box

In the switch box I can see a bundle of neutral wires, but I can't tell if the white wire to the outside of the house for the light is a neutral wire.

Can I install the light by simply hooking up the corresponding wire colors without knowing if it's a neutral? The house was built in 2005.

  • The light doesn't really care which side is which. It's alternating current anyway.
    – njzk2
    Commented May 30, 2023 at 21:16

3 Answers 3


Neutrals are not switched, that is why there is no neutral on the switch but it is in the box.

At the light source you already have the Hot and neutral.

  • 2
    Or more simply, a light switch is Hot in and Hot out. Only in high amperage usage at 20A or greater that you need a two-pole switch.
    – Nelson
    Commented May 30, 2023 at 13:14
  • 3
    To be picky, neutrals are not suppose to be switched, but mistakes in wiring are made. Stuff still works as it should, so checking at the switch is a good idea.
    – crip659
    Commented May 30, 2023 at 13:32
  • If you switched the neutral, someone's going to turn the light off to switch a lightbulb but get a shock instead. It's definitely dangerous to switch the neutral.
    – Nelson
    Commented May 31, 2023 at 8:37

Lights/receptacles(outlets) need neutral, switches do not.

If just connecting at the light, then it same colour to same colour, for that location with a single cable to the light.

  • Thanks for the reply! I updated the post with a multimeter reading: the switch is turned on, the outside black wire reads 120v and the white 0. Both outside wires are 0 when the switch is turned off. So the switch is only controlling the electrical flow correct? Meaning that inside the box there is a neutral so that should be taken care of if I'm understanding?
    – v15
    Commented May 30, 2023 at 0:28
  • How exactly are you testing the hot and neutral wires? Are you testing it hot+ground and neutral+ground?
    – Nelson
    Commented May 30, 2023 at 13:19
  • I put the red probe on each with the black probe on the ground, yes. Is that the correct way to do it?
    – v15
    Commented May 30, 2023 at 15:20
  • 1
    Dumb switches don't need a neutral. However, code requires a neutral to be brought to switch locations for smart switches.
    – Mazura
    Commented May 31, 2023 at 2:25

That's wired up exactly how it should be.

The switch has Hot coming into it, and Switched Hot coming out of it (i.e. it's only hot when the switch is on).

The light, in this specific wiring setup, is therefore receiving switched hot (the black), and then exiting through neutral.

Yes, the colors are correct in the light box: the white is neutral, the black is power (i.e. switched power).

Here's your existing setup, with the unrelated switch removed so you can see what's going on:

enter image description here

  • Awesome! Thank you so much!!
    – v15
    Commented May 30, 2023 at 17:32

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