Cable tray rooms must comply with NEC requirements for working space and egress, ensuring safe access for maintenance and emergency exit, with at least one entrance and egress for equipment over 6 feet wide containing overcurrent or control devices.

NEC Requirements for Electrical Room Egress

According to NEC 110.26(C)(2), rooms containing equipment rated 1200A or more and over 6 feet wide that include overcurrent devices, switching devices, or control devices must have at least one entrance and one exit from the required working space to ensure safe access and egress . This ensures personnel can safely enter and exit the room during maintenance or emergencies. If only a portion of the equipment contains overcurrent devices and is less than 6 feet wide, the requirement may be interpreted based on the width of that specific section, but local authority approval is recommended .

Cable Tray Entry and Exit Points

Cable trays allow cables to enter or exit from the top or bottom of the tray, depending on the type of tray used:

• Ladder cable trays: Cables can exit through the top or bottom; proper bending radii must be maintained to avoid damage .
• Ventilated trough trays: Small-diameter cables may exit through bottom ventilation holes or the top; drop-out bushings can protect cables in vibrating environments . When routing trays over equipment such as motor control centers (MCCs) or switchgear, cables typically exit the bottom of the tray into the top of the equipment, ensuring compliance with bending radius and safety standards .

Working Space Considerations

Cable tray rooms must maintain adequate working space around equipment for safe operation and maintenance:

• Minimum clearances depend on voltage, equipment type, and NEC specifications.
• Cable trays should not obstruct required egress paths or violate bending radius requirements.
• Ladder or trough tray rung spacing should be selected to allow proper cable installation without modifications that could compromise safety .

Practical Recommendations

• Ensure at least one clear entrance and exit for rooms with large switchboards or cable tray systems.
• Verify that cable tray routing does not block egress or violate NEC working space requirements.
• Use drop-out bushings or protective fittings where cables exit trays to prevent abrasion or damage.
• Coordinate with local authorities to confirm interpretations of NEC requirements, especially for sections of equipment partially containing overcurrent devices . By following these guidelines, cable tray rooms can meet both safety and code compliance, ensuring proper access, egress, and cable management.