I want to control an outside light with an inside timer switch. This is on a 3 way switch arrangement. The new timer has 4 wires(B/W/R and Green) and the feed only has 3(B/W/R). The diagram shows the green and red are both "travelers", Do they both get connected to the red feed? What arrangement should I use?
Your timer is not set up for a 3-way switch; it is missing the blue wire. You need to get a timer switch that has the blue wire.
In the diagram, "GROUND" is the green wire.
This is incorrect. What's more, the underlying assumptions are incorrect. I don't know where to start, but let's start with what should be.
Your idea of hooking like colors together is fair. I just rewired a building in conduit where every splice was orange-orange, gray-purple to gray-purple, etc. But I have 10 colors of wire and 10 colors of tape.
This falls apart in house wiring where multi-conductor cable is used. It only comes in two styles:
- Black, white and bare
- Black, white, red and bare
As such, color coding is a matter of futility. The only thing you know for sure is that neutrals must be white -- but white wires may not be neutral. I, for one, fix this with colored tape. The 5 colors in the 3 dollar multi-packs will suffice when added to the normal black that should be in your toolbox.
So your first problem right out of the chute is that you don't know which wires are the messengers. And let me guess, you don't even really understand how normal 3-way switch wiring works, do you? Yeah... that'll help a lot.
I like to mark messengers both with yellow tape. The fact that two are thusly marked means they can be nothing but messengers. If there are other groups of messengers in the box, then maybe also blue. White, gray and green should not be used on a white wire as this is ambiguous.
So to start with, I'd roll back to a regular 3-way, and swap wires around on the 3-way until it works normally again (i.e. both 3-ways work). Then you can mark the messengers; they are on the brass colored screws. The one on the black is common, which can be always-hot or switched-hot; it is never neutral.
Your other notion is that a smart-switch can be exchanged "with same wiring" as the switch it replaces. That is fair, though a better word would be "optimistic". And just isn't so with this particular product.
Also, by the absence of a blue wire, it's clear this is not the model that supports 3-way. Back to the store it goes. You may be better off buying at a proper lighting and electrical supply; they are much better at not wasting your time, which the big box stores love to do.
So your course of action here is to scope out the inside of the box and see whether a neutral is even present. And/or change locations to one where neutral is present and part of the 3-way cable (it is likely in either this 3-way box or the other). Do not use any random neutral from any random circuit, the neutral must be connected with this 3-way circuit.