I ran a new 12-3 romex to kitchen for future hook-up during kitchen remodel. After reading this messageboard, I realized my mistake, not running two separate 12-2. Now, I don't want to use this 12-3 romex, as planned, to feed kitchen countertop outlets due to potential GFCI tripping. Can I use this 12-3 romex to feed refrigerator and microwave? I have the option to use the existing circuits for the countertop outlets. Running additional new wires will be a lot of work. Please suggest the best remedy. Thank you.
You can run two circuits from it, however, each outlet will need to be on a GFCI. If you can split the 12-3 in the kitchen into two separate 12-2 lines, you can do that and have the first outlet a GFCI that controls the rest.
You can also use it for non-GFCI circuits.
However, with any shared neutral circuit, you have to be careful that the neutral stays connected. It can not go into an outlet and back out. It has to be wire nutted, and a pigtail to the outlet. If the neutral comes loose, the two circuits will be in series with each other at 220 volts and will cause damage to the appliances.