Ivan Vegvary writes:
After running two separate circuits for my daughter's dishwasher and waste disposal, I was told that I could have simply run a three wire cable (still 2 breakers) from the panel box and fed the appliances separately.
I understand the concept, but, there would be 2 hot wires and only one neutral.
Would not that neutral carry twice the current it is designed for?

It depends. This is commonly known as an "edison circuit". If each
of the two breakers were on different legs of the 240v service, then the
current in the grounded conductor will cancel out, such that if full load is
drawn on both of the two hot conductors, the current flow in the
grounded conductor (aka neutral) will sum to zero.

If they're on the same leg, then yes, you'll draw 2x the current
on the grounded conductor, which would be a code violation.

Using a commercial handle-tie 240v breaker is recommended, as it will ensu

a) That the two circuits are on opposite legs
b) That both circuits must be disconnected simultaneously.