Understanding NEC Article 620: Elevators, Dumbwaiters, Escalators, Moving Walks, Platform Lifts, and Stairway Chairlifts

NEC Article 620 outlines electrical safety requirements for elevators, dumbwaiters, escalators, moving walks, platform lifts, and stairway chairlifts. These standards ensure proper wiring, grounding, and equipment installation for safe operation and maintenance.

Scope of Article 620

This article applies to:

• Electrical equipment and wiring for elevators, escalators, and similar systems.
• Associated machinery, control spaces, and passenger environments.

Referenced Standards:

• ASME A17.1: Safety Code for Elevators and Escalators.
• ASME A18.1: Safety Standard for Platform Lifts and Stairway Chairlifts.

Key Requirements for Elevators and Related Systems

1. Voltage Limitations
   • Power circuits must not exceed 1000 volts for motors and control systems.
   • Lighting and heating systems must comply with relevant voltage limits under Article 410.
2. Wiring Methods
   • Hoistways, cars, and machinery spaces must use approved wiring methods such as metal conduits or flame-retardant cables.
   • Flexible cords can connect moving parts, provided they are secured and protected.
3. Grounding and Bonding
   • Equipment frames, enclosures, and metal raceways must be bonded to the system’s grounding conductor.
   • Compliance with Article 250 ensures safety against electrical faults.
4. Disconnecting Means
   • Separate disconnects are required for:
     • Main power supplies.
     • Car lighting and receptacles.
     • Heating, ventilation, and air conditioning systems.
   • Disconnects must be lockable and located for easy access.
5. Overcurrent Protection
   • Overcurrent devices must be tailored to intermittent loads like elevator motors.
   • Selective coordination is required for systems with multiple elevators sharing a power source.
6. Branch Circuits and Lighting
   • Lighting circuits must remain operational during power failures.
   • GFCI protection is mandatory for receptacles in machine rooms, hoistways, and pits.
7. Traveling Cables
   • Elevator cars and hoistways require listed traveling cables, supported to minimize strain and protect against physical damage.
   • Cables must include power, control, and communication conductors.
8. Emergency Power Systems
   • Elevators may connect to emergency or standby power systems as required by Article 701.
   • Regenerative systems must absorb returned energy during operation.

Applications

NEC Article 620 ensures safety in:

• High-Rise Buildings: Passenger and freight elevators.
• Commercial Spaces: Escalators and moving walks.
• Accessibility Solutions: Platform lifts and stairway chairlifts.

Conclusion

NEC Article 620 establishes crucial safety standards for elevators and similar systems. With requirements for wiring, grounding, overcurrent protection, and emergency power integration, this article ensures the reliable and safe operation of vertical transportation systems.