wiring 4 way switch with 2 dimmer zones
Cables for the two zones (or strings) of lights have to be run from the box with the dimmers. Your present setup of power to the lights run from the upstairs box won't work.
Scenario 1. The upstairs switch is a primary or master switch that feeds power to both dimmers downstairs. The 3 way switch already up there can stay, feeding power using one of the travelers; the other traveler is not used. If the upstairs switch is off, the dimmers do not act as 3 way and will not turn the lights on.
Scenario 2. Upstairs has one primary 3 way switch. Downstairs has one primary 3 way switch and also the two dimmers (3 gang box). This permist either location to turn on the lights although dimming action only works from downstairs.
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