1) Hello Sam......thank you for your replies as well as the drawings.
2) Just as an FYI, there is no such thing as a 2-way switch.
2A) Single Pole switches control a light from 1 location only.
2B) 3-way switches - the name is XXXXX XXXXX when used in a pair, they only control a light from 2 locations
2C) 4-way switches - these are used in conjunction with (2) two 3-ways. A 4-way switching arrangement controls a light from 3 or more locations.
3) The insulated white cable that you have connected to each of the existing 3-ways is 14-3 Romex. In order for the Z-Waves to work, both of your existing 3-way wall boxes require a white neutral wire originating from the branch circuit.
Refer to the picture below. Note the back side of each switch showing a neutral connection?
It appears that the upstairs wall box has the required white neutral (the 3 whites that are spliced together). However the downstairs wall box does not have the required white neutral. The white wires that are currently connected to each of the existing 3-ways are not neutral wires, those are traveler wires which inter-connect each switch.
4) The Z-Wave's only require (1) one traveler wire, unlike your existing 3-ways which require 2 travelers. You will need to remove the existing white traveler wire from each switch and splice into the 3 whites that are currently spliced together. This will now provide you with the required white neutral at the downstairs wall box.
The red wire will be used as your Z-Wave traveler connecting to each of the Z-Waves.
Refer to page 6 on the instruction sheet for your existing 3-way arrangement and directly below that is another diagram for wiring the new Z-Waves.
Hope this helps.........If you have any additional questions, let me know and I'll be glad to answer them for you.
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