There is possibly a grounding issue. Ground all unused conductors in the same cable as the power conductors. Be sure to use shielded cable and verify that both ends of the cable are grounded.
Yes. Always review power calculations to verify amperage and voltage limitations.
Yes.
The MS08 has a 4-wire configuration:
red and black = power
white = common
green = normally open
spare terminal = normally closed (if needed)
The relay hold time potentiometer (POT).
MS21 = yes (DIP)
MS08/09 = N/A
MS11 = yes (jumper)
MS21H = N/A
MS08/09 = yes (output switch)
MS11 = yes (output mode jumper)
Only the MS21 requires shielded wire. All other Magic Switch products (MS08, MS09, MS11) require a standard grade, 4-conductor cable.
Using the 900 MHz Retrofit Transmitter, a Magic Switch can transmit wirelessly but still requires power to be hard-wired.
MS08: 4″ to 24″
MS09: 4″ to 24″
MS11: 2″ to 24″
MS21: 0″ to 4″