I try to save money on certain projects but electrical is not the
trade to do questionable work.There are safety factors which are
important,also if there is a fire which is traced back to your
questionable work your insurance will be voided. I urge you to get the
proper materials and do an installation that meets code.If you unsure
of your electrical abilities, pull a permit & have it inspected.
Todd

If I want to run an appliance that needs 50 amps, is there any problem
with combining two 30-amp circuits of approximately the same length, as
long as the part that carries the full current is using properly-sized
cable? It seems like the circuit would have a 60 amp capacity.

Thanks in advance.