Does the cable sheath need to be stripped down to the cable tray

Cables installed in cable trays or ladder systems should generally remain sheathed; the sheath is not stripped down to the tray except at connection points.

Key Considerations

Mechanical Protection: Cable trays and ladders are designed to support cables, not to provide full mechanical protection. Therefore, only cables with adequate sheathing—such as PVC, MICC, fire-resistant, or steel wire-armored cables—should be used in trays to prevent damage and comply with safety regulations (Regulation 521. 10.

1). Stripping the sheath along the tray would expose conductors to abrasion and potential hazards. Connection Points: Stripping of the cable sheath is only required at the ends where the cable connects to equipment, terminals, or junction boxes.

For example, NEC Section 334. 19 specifies that nonmetallic-sheathed cables must extend at least ¼ inch beyond a cable clamp before the sheath is stripped to expose conductors, ensuring protection from abrasion. Tray as Protective Conductor: Cable trays themselves are not typically used as protective conductors.

The sheath provides fault protection, so earthing of the tray is not generally required unless the tray is metallic and intentionally bonded as a protective conductor. Installation Best Practices: When installing cables in trays, ensure that sharp edges or modifications to the tray are smoothed or sealed to prevent damage to the cable sheath. Bundling and balancing cables in the tray helps maintain mechanical integrity and reduces stress on the sheath.

Summary

Do not strip the cable sheath along the tray; keep the protective layer intact. Strip only at connection points to terminals or equipment. Use properly sheathed cables suitable for open-air tray installation.

Protect cables from sharp edges and mechanical damage during installation. Following these practices ensures compliance with electrical codes, maintains mechanical protection, and reduces the risk of electrical faults or damage to the conductors.