This is lighting diagram for a room. The existing wiring (Lamp A) is a switched loop. The switch is a combo switch (Blue Box) and I want to use the unused second switch for the new lamp. What I want to add is in the orange box. (Lamp B)

All the wiring is in the attic which I can access.

Since this is a switched loop, the terminals at the existing switch are hot.

I have the black and white wires running to the unused switch.

Where do I connect back to neutral?

Are there any wiring diagrams for this arrangement?

How should I wire the new switch and wiring?

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  • 1
    Is there somewhere else you can pull power from? Dec 3, 2020 at 0:28

1 Answer 1


You don't.

When you have a traditional "switch loop" like that, you can't extend anything off it.

The essential wires you'd need for anything else to come off it, simply are not there.

A lot of people get confused because they see black and white wires and think "those are the wires I need". No. The wires are black and white because that's how cables are made. In any given circuit, the black and white are reassigned to the needs of the moment depending on where it is.

On a switch loop, there is no neutral. White has been re-tasked to be always-hot. Black is switched-hot. No neutral, no circuit extension possible.

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