NEC Article 620 outlines the requirements for the installation, operation, and maintenance of various lifting devices, including elevators, dumbwaiters, escalators, moving walks, platform lifts, and stairway chairlifts. Here is a comprehensive overview of the key sections within this article:
620.1 Scope
This section covers the installation of electrical equipment and wiring used in connection with elevators, dumbwaiters, escalators, moving walks, platform lifts, and stairway chairlifts.
620.2 Definitions
Defines essential terms related to the equipment covered by this article, ensuring clarity and consistency in application.
620.3 Voltage Limitations
Specifies that the supply voltage for elevators and similar equipment must not exceed 300V between conductors. Exceptions are made for certain lighting, HVAC, and power circuits.
620.4 Enclosures
All live parts must be enclosed to protect against accidental contact, aligning with the requirements of Article 110.
620.5 Working Space
Adequate working space must be provided for maintenance and inspection, with clearances not less than those specified in Article 110.26.
620.11 Conductors and Insulation
Conductors for hoistway door interlocks and other critical systems must have flame-retardant insulation. Traveling cables must also meet specific requirements for flexibility and protection.
620.13 Feeder and Branch-Circuit Conductors
Conductors must have an ampacity based on the nameplate current rating of the driving motor, and they must comply with the requirements for motor loads as specified in Article 430.
620.14 Overcurrent Protection
Outlines the requirements for overcurrent protection devices for conductors and equipment to prevent electrical faults and ensure safe operation.
620.21 Wiring Methods
Specifies acceptable wiring methods and materials for connecting lifting devices. Not all Chapter 3 wiring methods are allowed; only specific types of raceways are permitted.
620.22 Branch Circuits for Car Lighting, Receptacles, HVAC
Permits branch circuits to supply additional loads such as emergency responder radio coverage circuits and car emergency signaling devices. The OCPD for air conditioning and heating sources must be located as specified.
620.23 Branch Circuits for Machine Room, Control Room
Requires at least one 125V, single-phase, 15A or 20A duplex receptacle for truss interiors, which are structures of moving walkways and escalators.
620.24 Disconnecting Means
A disconnecting means must be provided for each lifting device, and it must be accessible, lockable, and capable of opening all ungrounded conductors simultaneously.
620.30 Grounding and Bonding
Outlines grounding and bonding requirements for all metal parts, ensuring a continuous path to ground to minimize the risk of electrical shock.
620.50 Control Systems
Details the requirements for control systems, including the installation, protection, and maintenance of control equipment to ensure safe and reliable operation.
620.51 Lighting for Hoists
Adequate lighting must be provided for hoist machinery spaces to ensure safe operation and maintenance.
620.61 Mechanical and Electrical Interlocks
Mandates the use of mechanical and electrical interlocks to prevent unsafe operation of cranes and hoists.
620.62 Warning and Notification Systems
Specifies requirements for warning and notification systems to alert operators and personnel of potential hazards.
620.64 Inspection and Maintenance
Outlines the requirements for regular inspection and maintenance to ensure equipment remains in safe operating condition.
620.67 Modifications and Additions
Details procedures for modifying or adding to existing installations, ensuring all modifications comply with NEC standards and do not compromise safety.
For more detailed information and specific requirements, consulting the NEC Handbook and additional resources provided by the NFPA is highly recommended. More insights can be found on resources like iBidElectric and The NEC Wiki.