Wondered how the NEC feels about using parallel feeders instead of footing the cost for more expensive larger sized wire? Application is UF-B from house to detached garage. Want to use 2 sets 12-3, WG instead of paying for 10-3 WG (or 8-3 WG). Am not interested in having an inspection.

I can't give you what code says. I do know it is quite common to use multiple wires to carry large industrial 3 phase loads. I have seen things like 3 conduits each carrying three 500 MCM singles. They are quite common in factories.

I can't give you what code says. I do know it is quite common to use multiple wires to carry large industrial 3 phase loads. I have seen things like 3 conduits each carrying three 500 MCM singles. They are quite common in factories.
... it would be a better bet to place them in PVC conduit so if they ever are found to violate code, they can be replaced easier. You agree, Labman?

Certainly wouldn't hurt. Do you already have a big coil of 12-2? Again you buy 2 lengths of it plus the conduit, surely one length of 10-2 would be cheaper. Also if you run conduit, you could run singles rather than cable. Stranded singles pull easier than solid cable.

Per the current edition of the National Electric Code:

"Section 310.4 Conductors in Parallel.
Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and larger, comprising each phase, neutral, or grounded circuit conductor, shall be permitted to be connected in parallel (electrically joined at both ends to form a single conductor)."

Should you install electric wiring without proper licenses or permits, and loss of life and/or property occurs due to improper installation, you insurance will not cover your losses.

Something to consider.. save a few bucks now, and pay large bucks later.

Per the current edition of the National Electric Code:

"Section 310.4 Conductors in Parallel.
Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and larger, comprising each phase, neutral, or grounded circuit conductor, shall be permitted to be connected in parallel (electrically joined at both ends to form a single conductor)."

Should you install electric wiring without proper licenses or permits, and loss of life and/or property occurs due to improper installation, you insurance will not cover your losses.

Something to consider..save a few bucks now, and pay large bucks later.
... info and the reminder of just how dangerous electricity is!