Is a bell end required on an underground PVC stub up?

Yes. NEC 300.5(H) requires a bushing or terminal fitting where conductors emerge from a raceway or where a raceway terminates underground, to protect conductors from abrasion.

Does PVC entering a box need a bushing?

NEC 352.46 requires a bushing or adapter where PVC conduit enters a box, fitting, or enclosure, unless the enclosure design provides equivalent protection from abrasion.

What size conductors always require a bushing?

NEC 300.4(G) requires an identified fitting with a smoothly rounded insulating surface where insulated conductors 4 AWG or larger enter a raceway in a cabinet, box, or enclosure.

Do PVC conduits need a bell end?

If the raceway comes out of the ground and the conductors leave the raceway at that point, yes, you need a bushing or a terminal fitting, and a bell end is the usual way to do it. The rule is Section 300.5(H) of the 2023 NEC, and it does not care whether the conductors go into an enclosure or into open air.

What 300.5(H) requires

Section 300.5(H) covers raceway seals and terminations for underground installations. Where a raceway enters from an underground system, the end within the building shall be sealed with an identified compound so as to prevent the entrance of moisture or gases. Directly relevant here, conduit or raceways through which moisture may contact live parts shall be sealed or plugged at either or both ends. And where a raceway terminates underground or where conductors emerge from a raceway, a bushing or terminal fitting shall be provided to protect conductors from abrasion. A bell end fitting, an end bell, or a listed terminal adapter with a bushing all satisfy that requirement.

The reason is mechanical, not electrical. A saw cut or a molded PVC edge is sharp enough to slice insulation during a pull, and it stays sharp for the life of the installation while the conductors flex under thermal cycling. A bell end gives the conductor a radiused surface to bear against.

Entering a box or enclosure

Section 352.46 covers PVC bushings. Where a conduit enters a box, fitting, or other enclosure, a bushing or adapter shall be provided to protect the wire from abrasion unless the box, fitting, or enclosure design provides equivalent protection. A female adapter with a listed plastic bushing satisfies this. A terminal adapter with a locknut and a listed bushing is the usual method when landing PVC on a metal enclosure.

Section 300.4(G) adds a separate rule that applies at any raceway termination, not just PVC. Where insulated conductors 4 AWG or larger enter a raceway in a cabinet, box, enclosure, or raceway, the conductors shall be protected by an identified fitting providing a smoothly rounded insulating surface, unless the conductors are separated from the fitting or raceway by identified insulating material securely fastened in place. So on large service conductors, the bushing is required by two different sections.

Stub ups into free air

The question that comes up on farm and site work is a PVC stub up where conductors leave the top of the conduit into open air, feeding a pole light or a pump. Section 300.5(H) still applies because conductors are emerging from a raceway. Put a bell end on it. Also check Section 300.5(D)(4), which requires the raceway to have a suitable termination fitting where direct buried conductors and cables emerge from grade, and Section 352.10 for permitted uses of PVC, along with 352.12 which prohibits PVC where subject to physical damage unless identified for that use. Where the stub up is exposed and subject to damage, Schedule 80 PVC or a change to rigid metal conduit is the common answer.

Field takeaway

Any PVC end where conductors exit gets a bell end or a listed bushing. Any PVC entering an enclosure gets an adapter and bushing. On 4 AWG and larger, treat the bushing as mandatory under 300.4(G) regardless of the raceway type.