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I want to put two 3-way switches in the same box. I'm uncertain what splices I have to make, but I have an educated guess. (Diagram below)

Here's my assumptions:

  • The hots (black) from the 14-3 wire get spliced together with: the source hot and hots running to each switch

  • The 14-3 reds do not get spliced together.

  • A hot from each light fixture runs to it's switch

Does this look accurate and code compliant with NEC (red rectangles indicate marretts) ?

The diagram shows two switches for two different lights, each part of their own 3-way. In case the notation wasn't clear, the green circle is a grounding screw (this is a metal 2-gang box)

(Note: It looks like some of my neutrals in my diagram are hidden by grounds. I plan to splice all neutrals in the box together)

enter image description here

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    This is really confusing. A 3-way (at least in the US) normally has power->switch 1->switch 2->light or power->light->switch 1->switch 2. In either case, normally two travelers between switches, power in (hot) on one switch, switched hot out on the other switch. You are showing only one of each switch and appears to be a single traveler going between switches. – manassehkatz-Moving 2 Codidact Oct 31 '20 at 23:32
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    Not so much confusing as "not gonna work that way because that's not the way it works." – Ecnerwal Nov 1 '20 at 0:30
  • If this is in the USA then you do not have enough wires installed between this junction box and the two remote switches (the ones off the diagram to the bottom). Modern NEC code requires the presence of both constant-hot and neutral at every switch. You have 12/3wG running to the remote 3-ways; you will need to install 12/4wG. – A. I. Breveleri Nov 1 '20 at 0:58
  • @A.I.Breveleri -- you only need that at one location within a 3-way complex – ThreePhaseEel Nov 1 '20 at 0:58
  • Thank you @ThreePhaseEel. - In that case OP has installed enough wires. I will try to correct his diagram. – A. I. Breveleri Nov 1 '20 at 1:01
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There are several ways to wire this circuit, but this is the one that will be least confusing to any future maintainers (which might even be you, two or three years from now).

two 3-way drop loops with power at near switches

I have put a "C" next to the common terminal on each switch.

Note that the white wires running to the remote 3-ways are marked with black paint or tape at both ends to indicate that they carry constant-hot and not neutral.

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  • A. I. thanks for the level of detail. Please bear with me while I ask a stupid question with probably poor terminology. In your revised diagram, the power source 14/2 doesn't connect to any of the terminals on the switches in the box. How does that work? – AfterWorkGuinness Nov 1 '20 at 14:11
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    Power goes first to the remote switches, then returns to the local box via the red and black wires. - For each light, power always returns by either the red or black wire, but never both. – A. I. Breveleri Nov 1 '20 at 16:34
  • Thanks for the answer. One more question, I have reservations if this is allowed by code in Canada, can you describe an alternate way that doesn't involve using the white conductor to carry power? – AfterWorkGuinness Nov 4 '20 at 22:22

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