Overspeed Protection

DOE-HDBK-1092-98

6.3.2.6 OVERSPEED PROTECTION

Overspeed protection for overhauling and under-hauling is required, as are motor-generator over-

speed requirements that must comply with NEC Section 430-89, Speed Limitation. However, these

requirements are a part of the more extensive requirements of ANSI/ASME A17.1 for electrical

safety devices, which require scrutiny by designers, maintenance personnel, and inspectors.

6.3.3 EMERGENCY POWER

Emergency power requirements are governed by ANSI/ASME A17.1 Rule 211.2, which requires

that the regenerative power of an overhauling elevator prevent the elevator from attaining the lesser

of the governor tripping speed or 125% of rated speed. If the elevator power system cannot absorb

this power, a load shall be provided on the load side of the elevator power disconnect switch. If an

emergency power supply is designed to operate only one elevator at a time, the energy absorption

means may, if required, be located on the line side of the disconnect. Other building loads that may

be supplied by the emergency power source may not be considered as absorbing regenerated energy

unless they use the emergency power source as normal power. Refer to Article 620, Part K, of the

NEC, Overspeed, for the installation requirements covering these requirements.

6.3.4 DESIGN

In addition to the NEC, elevator and escalator requirements, there are numerous electrical requirements

for the facilities designer in ANSI/ASME A17.1 and A17.3. ANSI/ASME A17.1 is a required

reference for new elevator and escalator installations and can be used by the designer in checking

submittal drawings from the manufacturer. ANSI/ASME A17.3 provides the safety requirements for

existing elevators and escalators and shall be referenced when existing installations are to be

modified or to determine which modifications shall be made to existing installations and equipment

to maintain optimum safety. The following lists typical key electrical requirements from ANSI/

ASME A17.1 that the designer shall control over and above those from the NEC.

1. Access to elevator equipment is to be controlled and limited to authorized persons.

2. Elevator equipment cannot share space with other building equipment except when the

elevator equipment is separated from other equipment, enclosed by a rigid wire fence, and

provided with a lock that is strictly for that enclosure.

3. Only electrical wiring, including raceways and cables, used directly in connection with the

elevator, including wiring for (a) signals, (b) communication with the car, (c) lighting,

heating, air conditioning, and ventilating the car, (d) fire-detecting systems, (e) pit sump

pumps, and (f) heating and lighting the hoistway may be installed in the hoistway.

4. A minimum lighting level of 108 lux for the equipment rooms and spaces and 54 lux on the

floor of the pit is required. The basis for the specified illumination level should be in

accordance with the Illuminating Engineering Society (IES) lighting handbook.

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