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I have two separate 3-way lights that need to be powered from the same power source in one box (in addition to using the box as a junction to supply power to a different box, but I can't see why that would matter). So I have the 14-2 cable coming in from the panel, and its hot lead is pigtailed to the power going out, and to the top (brass) screws of each of the 3-way switches. The neutrals are all tied together. The red and black travelers from the bottom two screws (brass and black) of the switches are going out to the other 3-way switches in two different boxes, and then a 14-2 switched leg goes up to power the lights from there, just like this diagram:

enter image description here

I thought it would be pretty straightforward, to just pigtail the hot line, and wire up two circuits this same way. And when I only had one of the 3-way circuits wired up, it was functioning like it should. But when I put the other circuit together, now something is screwy, where the 3-way of the first circuit is affecting the functioning of the second circuit.

Where did I go wrong, and what is the correct way to wire up two separate 3-way circuits powered by the same 14-2 cable going back to the panel?

5000fingers
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3 Answers3

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hot lead... to the top (brass) screws of each of the 3-way switches... The red and black travelers from the bottom two screws (brass and black)

I think you're in for a big surprise on that configuration. "top" and "bottom" don't mean a thing on a 3-way switch (not least the switch can be flipped over). What designates the common is the black screw.

I've held 4 random 3-way switches in my hand, oriented the ground screw "down", and I was looking at 4 different arrangements of terminals. It's amazing. Even 2 switches in the same bin can differ. (probably something to do with economically using the brass they stamp the pieces out of).

Harper - Reinstate Monica
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Try like this:

2x 3ways in same box

The power "line" leads from each set of 3-ways are wire-nutted together to the wires from the panel in parallel.

Grounds are all connected, too, of course.

Triplefault
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The hot (black) wire coming into a three way switch is ALWAYS to the black screw terminal.

The (black) conductor going to the light(s) from a three way switch are ALWAYS coming from the black screw terminal.

The (travelers) don't matter as long as they're on the brass screws terminals.

The neutrals (white) should be connected together. Neutrals should not be mixed on different circuits (breakers), and never to a hot conductor.

The grounds (bare or green) only get connected to (bare or green) conductors, and bonded to all metal parts (excluding wires).

This is for 120 volt Romex.

Steve
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