I was swapping a breaker inside my panel and noticed something that struck me as odd--the garbage disposal and dishwasher are both being served by a single cable that contains a pair of red/black hots (marked "14-3 w/ ground"). Whoever hooked it up in the first place had connected the two hots to two separate 20 amp breakers that were positioned opposite each other. Now, the wires are only 14 gauge, so 20 amps is too much to begin with. But even if the breakers were 15, would there be a risk of allowing more current than that since two breakers are involved, or would both trip together the moment 15 amps was exceeded? The breaker type (square D QO) can accept two wires; would it be better to connect both hots to a single (15 amp) breaker?
Edit: The cable terminates in an outlet where the dishwasher is connected with a NEMA L5-20 plug (I'm finding 14-gauge wire mixed with 20 amp stuff all over the place here. Sigh). A short length of 14-2 w/ ground runs from the outlet box to the switch that controls the disposal, and another 14-2 w/ ground runs from the switch to the disposal itself. The cord between the plug and the dishwasher is also 14-2 w/ ground.