009770-000000-0000001 Scope
1.1 These requirements cover fused power-circuit devices to be employed in accordance with NFPA 70®, National Electrical Code® (NEC®). Fused power-circuit devices, as covered by these requirements, are considered to be either bolted-pressure contact switches or high-pressure butt-type contact switches. Bolted-pressure contact switches are devices in which the blade-jaw connections have an additional pressure or clamping action provided at both ends of the switch blades when the blades are in the fully closed position. High-pressure butt-type contact switches are devices having butt-type contacts and a spring-charged mechanism.
NFPA 70®, National Electrical Code®, and NEC® are registered trademarks of the National Fire Protection Association, Quincy, MA.
1.2 Fused power-circuit devices may be manually or electrically operated and may incorporate electrical tripping means. An electrically tripped device is one whose closing is performed manually or electrically but contact opening is performed by a release energized by a separate source of voltage. A device with an electrical operator is one whose contact closing and opening is performed by electrical means.
1.3 Fused power-circuit devices have continuous current ratings of more than 600 A and voltage ratings of 600 V or less AC, DC, or both. Devices rated AC are intended for use on circuits having maximum available short-circuit currents of 100,000, 150,000, or 200,000 A (rms symmetrical). Devices rated DC are intended for use on circuits having maximum available short-circuit currents of 20,000, 50,000, 100,000, 150,000, or 200,000 A DC.
1.4 Fused power-circuit devices have provisions for mounting (or are intended to be used with upstream) Class L fuses or Class T fuses rated more than 600 A.
1.5 These requirements cover:
a) Complete, enclosed fused power-circuit devices in which the switch is integral with the enclosure;
b) Open-type fused power-circuit devices intended for mounting in other equipment, such as switchboards or a separately shipped enclosure; and
c) Enclosures intended for mounting open-type fused power-circuit devices.
1.6 These requirements also cover electrically tripped and/or operated devices that have been evaluated to determine their acceptability for ground-fault protection when combined with ground-fault sensing and relaying equipment as follows:
a) Switches for use with Class I ground-fault sensing and relaying equipment including those devices that are capable of interrupting 12 times their rated current or that have integral means intended to prevent disconnecting at levels of fault current exceeding the contact interrupting capability of the switch; and
b) Switches for use with Class II ground-fault sensing and relaying equipment are capable of interrupting at 10 times their rated current and are for use in ground-fault protection systems where means intended to prevent disconnecting levels at fault current exceeding the contact interrupting capabilities of the switch are incorporated within the ground-fault sensing and relaying equipment.
1.7 These requirements do not apply to low-voltage AC integrally fused power circuit breakers as covered by the Standard for Low‐Voltage AC (1058 V and Below) Power Circuit Breakers Used in Enclosures, IEEE C37.13.