配管本体 埋める 電卓

For conductors 6 AWG and smaller with no splices, an LB follows the fill of the conduit connected to it. When splices or taps are present, NEC 314.16(C) volume rules apply and the body must be marked with its cubic-inch capacity, which then limits the conductor count.

A conduit body is a fitting (LB, LL, LR, T, C) that provides access to a raceway at a bend or junction, while a junction box is an enclosure for splicing and connecting conductors. They are sized under different NEC rules: conduit bodies under 314.16(C) and 314.28, boxes under 314.16(A) and (B).

NEC 314.16(C) governs conduit bodies used with conductors 6 AWG and smaller, using cubic-inch volume when splices exist. NEC 314.28 governs bodies and pull boxes containing conductors 4 AWG and larger, using minimum length and dimension multiples of the largest raceway to protect insulation.

Pass-through conductors without splices count toward fill the same way they count in the connected conduit for 6 AWG and smaller. A separately marked cubic-inch volume is only required when the body contains splices, taps, or devices.

Under NEC 314.28(A)(2) for angle or U pulls with 4 AWG and larger conductors, the distance from where a raceway enters to the opposite wall must be at least six times the trade diameter of the largest raceway. This protects large conductors from over-tight bends.

Yes, if the conduit body is marked by the manufacturer with its cubic-inch volume and the splices fit within that volume per NEC 314.16(C)(2). Unmarked conduit bodies may not contain splices, taps, or devices.