Overview

Regardless of environmental conditions such as dryness, moisture, corrosion, and physical damage, power delivery must remain uninterrupted. No single insulating structure or material can effectively counter all these factors and adequately protect the conductor. NEC Section 398.15, Exposed Work, outlines various insulating materials suitable for supporting or installing open conductors in challenging environments. However, the use of high-density polyethylene conduits (HDPE) is now prohibited in areas where the conductor may be exposed to physical damage due to safety concerns. While ensuring the reliability of power delivery is crucial, the safety of both users and electricians cannot be compromised. This change was implemented with safety as a top priority.

Applying the 2023 Code

Our daily power needs rely on conductors securely held in place by insulating materials. However, the installation of these conductors can be complex due to varying environmental conditions. As a result, it’s crucial to ensure that electricians don’t employ a one-size-fits-all approach.

NEC Section 398.15 specifies the requirements for installing open conductors in diverse environments, allowing for different support structures tailored to each scenario. However, the use of high-density polyethylene conduits (HDPE) is now prohibited in areas where the conductor faces potential physical damage. These conduits pose risks due to their flammability and susceptibility to cracking under stress, especially in certain situations. This change prioritizes the safety of both electricians and users.

What’s New for the 2023 NEC?

2020 NEC

In the 2020 NEC, Section 398.15(C) addressed the protection of open conductors in areas where they may be exposed to physical damage, permitting the use of high-density polyethylene conduits (HDPE) for such installations.

2023 NEC

In the 2023 NEC, the permission to use high-density polyethylene conduits (HPDE) was revoked in Section 398.15(C), which now reads as follows:

(C) Exposed to Physical Damage. Conductors within 2.1 m (7 ft) from the floor shall be considered exposed to physical damage. Where open conductors cross ceiling joists and wall studs and are exposed to physical damage, they shall be protected by one of the following methods:

1. Guard strips shall not be less than 25 mm (1 in.) nominal in thickness and at least as high as the insulating supports, placed on each side of and close to the wiring.
2. A substantial running board at least 13 mm (1/2 in.) thick in back of the conductors with side protections. Running boards shall extend at least 25 mm (1 in.) outside the conductors, but not more than 50 mm (2 in.), and the protecting sides shall be at least 50 mm (2 in.) high and at least 25 mm (1 in.), nominal, in thickness.
3. Boxing made in accordance with 398.15(C)(1) or (C)(2) and furnished with a cover kept at least 25 mm (1 in.) away from the conductors within. Where protecting vertical conductors on side walls, the boxing shall be closed at the top and the holes through which the conductors pass shall be bushed.
4. Rigid metal conduit (RMC), intermediate metal conduit (IMC), rigid polyvinyl chloride conduit (PVC), reinforced thermosetting resin conduit (RTRC), or electrical metallic tubing (EMT). When installed in metal piping, the conductors shall be encased in continuous lengths of approved flexible tubing.