On Sun, 08 Dec 2013 13:01:43 -0500, wrote:

On Sun, 8 Dec 2013 09:42:47 -0800 (PST), Edge
wrote:

At this home there is a 20 amp breaker in the electrical panel that is pencil labeled as for the dishwasher and garbage disposal. At the junction box on the kitchen wall near the sink we see the 12 gauge wire feeds from the panel. Three 14 gauge wires, hot-black/neutral-white/ground-green, are routed from this box to another junction box underneath the sink through conduit. A whip from the dishwasher is hardwired to the wires under the sink.

We want to add a GE half horsepower garbage disposal that is suppose to draw only 4.5 amps. Can we just pull another hot 14 gauge wire for the garbage disposal and use the existing white neurtal already there for the dishwasher? Does it matter whether 14 gauge is used rather than 12 gauge wires for either device?

All the wires should usually be #12 BUT if you are serving a pure
motor load like the disposal, you could use #14. (125% of FLA) Not so
with the dish washer since it is not a pure motor load.
Whether they can share the circuit would depend on the nameplate
rating of the dishwasher.

Mixing 12ga and 14ga on one branch? That sounds like a real no-no,
even if you used a 15A breaker.

Take 125% of the largest load and 100% of the other one. It has to be
20 or less.