Overview

When aboveground PVC conduits are exposed to the heating and cooling effects of the environment, we must utilize expansion fittings to absorb the expanding and compressing forces to protect the conduit’s shape and integrity. However, what about factors affecting PVC conduits underground? Section 352.44 Expansion Fittings has now been expanded to permit their use in underground PVC conduit installations to prevent factors like earth movement, earth settling, and frost heaving from damaging the conduit. Thus, PVC conduit protection has become more comprehensive than before.

Applying the 2023 Code

Rigid PVC conduits are widely utilized for installing electrical cables and conductors, owing to their excellent electrical insulation properties. Their use ensures the protection of conductors against stray currents/voltages and prevents unnecessary bending. However, these conduits must withstand environmental factors like humidity and temperature, which can pose challenges in certain applications. Temperature variations, in particular, can cause the conduits to warp significantly due to expansive and compressive pressures, potentially exposing hidden conductors to electrical and physical interference.

As electricians, it’s imperative to ensure the integrity of these conduits amidst such challenges. Thus, we must devise strategies to mitigate expansive and compressive forces. The most effective solution thus far has been the use of expansion fittings, which absorb these forces while minimizing their impact on the conduit itself. The introduction of these fittings has expanded the applicability of rigid PVC conduits to various scenarios, and ongoing efforts aim to enhance their effectiveness further.

To optimize the use of PVC conduits across diverse applications, the criteria for employing expansion fittings have evolved beyond temperature and weather resistance to encompass protection against pressures exerted by earth movement. This has facilitated the installation of PVC conduits in underground settings, broadening their utility within the industry.

What’s New for the 2023 NEC?

2020 NEC

In the 2020 NEC, Section 352.44 permitted the use of expansion fittings in aboveground PVC conduit applications to provide protection against temperature and weather conditions.

2023 NEC

In the 2023 NEC, the new Sub-Section 352.44(B) Earth Movement was added, which now reads as follows:

(B) Earth Movement

Expansion fittings for underground runs of direct buried PVC conduit emerging from the ground shall be provided above grade when required to compensate for earth settling or movement, including frost heave.