Elevators and escalators are used to move people and elevators are also used to move materials. Design, installation, inspection, and maintenance activities require specialized knowledge for safe operation and use.

6.3.1 CODES AND STANDARDS

A comprehensive electrical safety program for elevators and escalators can be achieved through the application of the guidelines in the following five standards:

1. ANSUASME A17.1, Safety Code for Elevators and Escalators

2. ANSUASME A17.2.1, "Inspectors Manual for Electric Elevators." ANSUASME A17.2.2, "Inspectors Manual for Hydraulic Elevators." ANSUASME A17.2.3, "Inspectors Manual for Escalators and Moving Walks."

3. ANSUASME A17.3, Safety Code for Existing Elevators and Escalators.

All elevators are required to be constructed, installed, and maintained in accordance with ANSI/ ASME A17.1. Reference standards include NFPA 70 (NEC) for the electrical equipment wiring and NFPA 101 (Life Safety Code), Chapter 6, Features of Fire Protection, and Chapter 7, Building Service and Fire Protection Equipment. These standards reflect the interrelated roles of electrical design, maintenance, and fire protection in the electrical safety process.

6.3.2 DESIGN SPECIFICATIONS

The electrical designer shall provide for the installation requirements of Article 620 of the NEC as well as the ANSUASME A17.1 requirements of Sections 102, 210, and 211 for signaling, automatic fire protection, and emergency power as required. The manufacturer shall provide the required fire service key switches, audible alarm devices, and internal wiring up to the terminal strips in the elevator control panel.

6.3.2.1 VOLTAGE AND CURRENT LIMITATIONS

There shall be a 300-V limitation on all operating control and signal circuits and related equipment, including door operators. Exceptions are permitted for 25 to 60 Hz ac if the current cannot under any conditions exceed 8 mA, or for do voltage if the current cannot, under any circumstances, exceed 30 mA.

6.3.2.2 CONDUCTORS

Hoistway door conductors from the door interlocks to the hoistway riser shall be flame retardant, suitable for a temperature of at least 200C, and Type SF or equivalent. See Table 400-4 of the NEC for approved types of elevator cables and Note 5 to Table 400-4 concerning special requirements for traveling control and signal cables. Operating control and signal cable conductors may be as small as #24 AWG. Traveling cable conductors must be #20 AWG or larger. (See NEC Sections 620-11 and 12).

6.3.2.3 DISCONNECTING MEANS

The disconnecting means requirements for elevators and escalators are both specific and extensive, requiring careful study of the codes and installation plans during design, acceptance testing, and routine inspections. Some of the basic requirements of NEC Section 620-51 are the following:

1. There shall be a single means of disconnecting all ungrounded conductors to the main power supply of each unit.

2. A single elevator or escalator, with multiple driving machines, shall have one disconnecting means to disconnect the motors and control valve operating magnets.

3. When there is more than one driving machine in a machine room, the disconnecting means shall be labeled per NEC Section 620-51 and 29 CFR 1910.303(f).

4. The disconnect shall be a fused motor circuit switch or circuit breaker capable of being locked open.

5. The disconnect shall not be provided with a means of being operated from a remote location.

6. A circuit breaker disconnecting means shall not be opened automatically by a fire alarm system, except as allowed by NEC Section 620-51(b).

7. The within-sight rule applies to all elevator equipment disconnects. Specific locations are given for elevators with or without field control.

8. The disconnecting means shall be installed in a location that is readily accessible to only qualified persons.

When power from more than one source is used for single- or multiple-car installations, a separate disconnect should be provided for each source. These disconnects should be in sight of the equipment supplied, and warning signs should be placed on or adjacent to the disconnect to read. For example, "Warning: Parts of the control panel are not deenergized by this switch."

Lighting circuits for each elevator require a disconnect switch in the equipment room labeled for the car it serves and lockable in the open position.