Switchgear

Standards

• Automatic Transfer Switches

  Automatic transfer switches rated 1000 V and below, listed to UL 1008, that move a load between a normal source and an alternate source without operator action. Covers the switching mechanism, transition type, bypass-isolation construction, neutral treatment, the controller and its sensing, time delays, exerciser, load management and communications provisions, ratings including withstand and closing and short-time ratings, service-entrance construction, enclosures, identification, factory and field testing, installation, warranty, and spare parts, for switches serving emergency, legally required standby, optional standby, critical operations, and health care essential electrical system loads.

• Concrete Equipment Pads

  Cast-in-place concrete equipment pads and housekeeping pads that receive mechanical, electrical, and plumbing equipment - generators, pad-mounted and dry-type transformers, switchgear and switchboard lineups, chillers, air handlers, condensing units, pumps, compressors, boilers, and similar equipment - whether the pad bears on grade, on an interior finished floor, on a structural slab, or on an exterior platform. Covers the decisions a pad standard actually owns: pad geometry and height, attachment to the supporting concrete, reinforcement method, cast-in and post-installed equipment anchorage, cast-in raceway and grounding provisions, liquid containment, surface finish and grout bed, isolation from adjacent construction, dimensional and anchorage tolerances, and the verification performed before concrete is placed and before equipment is set.

• DC Battery Systems

  Stationary battery systems with chargers providing 24, 48, 125, or 250 VDC control power to switchgear protective relays, breakers, transfer switches, communications, generator starting, emergency lighting inverters, and other critical control loads in substations, generating stations, industrial facilities, and electrical rooms. Covers vented lead-acid (VLA), valve-regulated lead-acid (VRLA), and vented nickel-cadmium (Ni-Cd) chemistries; their chargers; DC distribution; battery monitoring; and the battery room or cabinet. Cross-references the loads they serve (see Low Voltage Switchgear and Medium Voltage Switchgear) and grounding of the DC system (see Grounding And Bonding).

• Electrical Equipment Labels

  The labels, nameplates, directories and signs applied in the field to the enclosures of electrical equipment rated 1000 V and below, and of the medium-voltage equipment on the same project: switchgear, switchboards, panelboards, motor control centers, transformers, transfer switches, generators, drives, disconnects, starters, busway, meter enclosures and control enclosures. Covers the equipment identification nameplate with its designation and source, the nameplates on each device and compartment, the circuit directory, the warning and danger signs NFPA 70 requires on equipment for voltage, multiple sources, disconnect location, back-fed devices, series ratings and ungrounded systems, the arc-flash warning label as a product and its installation, the available fault current marking, service equipment signs, the marking of emergency and standby system equipment, nameplate material, colors, character heights and attachment, the ANSI Z535.4 format of safety signs, installation, warranty and spare stock.

• Electrical Rooms

  The dedicated indoor electrical room and the electrical closet as a space: the room that houses service equipment, switchgear, switchboards, panelboards, motor control centers, dry-type transformers, transfer switches, drives, UPS modules, control-power batteries and the open or paralleling generator sets installed indoors. Covers the working space and the dedicated electrical space the adopted electrical code requires about the equipment, headroom, the number of entrances, door swing, clear opening and panic hardware, locking and free egress, the fire-resistance rating of the enclosing construction where a code sets one, the exclusion of piping and ductwork foreign to the electrical installation, water protection at the door and on the floor, the heat-release basis and the ventilation or cooling performance the room has to deliver, the temperature and humidity limits taken from the equipment ratings, illumination and emergency illumination of the working space, the convenience receptacle, housekeeping pad provision, floor finish, the room ground bar, the signs on the room door, the coordination drawing that proves every clearance before the room is framed, and the field verification before the room is closed in and before equipment is set.

• Low Voltage Switchgear

  Metal-enclosed low-voltage power circuit breaker switchgear rated 1000 V and below, listed to UL 1558 and built to IEEE C37.20.1, in which drawout low-voltage power circuit breakers built to IEEE C37.13 are individually mounted in grounded metal compartments on a common bus, whether installed as service equipment, as the secondary of a transformer, or downstream of other distribution equipment. Covers the ratings and the short-time basis, the breakers and their drawout mechanisms, operation, trip units, and accessories, ground-fault protection, arc energy reduction, control power and control wiring, the protective relays, instrument transformers, metering, surge protection, and communications provisions built into the assembly, the bus, the structure and enclosure, compartmentalization and arc-resistant construction, identification, factory and field testing, installation, warranty, spares, and breaker handling equipment, for three-phase and single-phase AC systems in indoor and outdoor locations, including walk-in and non-walk-in outdoor housings.

• Medium Voltage Switchgear

  Metal-clad medium-voltage switchgear rated above 1 kV through 38 kV using drawout vacuum or SF6 circuit breakers, built to IEEE C37.20.2 and the ANSI/IEEE C37.04 / C37.06 / C37.09 series, for utility-customer substations, large commercial campuses, healthcare and higher-education central plants, data centers, and industrial facilities. Covers 5 kV, 15 kV, 27 kV, and 38 kV voltage classes, indoor and outdoor walk-in (protected aisle) configurations, arc-resistant ratings per IEEE C37.20.7, multifunction microprocessor protective relays, and optional IEC 61850 station bus communications.

• Short-Circuit Study

  The short-circuit study for a project's electrical power distribution system, from the utility point of delivery through every point at which an interrupting rating, a close-and-latch rating, a short-time withstand rating, a bus bracing rating, or a marked short-circuit current rating is confirmed, on AC systems rated 1000 V and below through 38 kV with utility, generator, inverter-based, and paralleled sources. Covers who performs the study and when it is delivered, the calculation method and the duty networks, the fault types and the maximum and minimum cases, the system model and the data it is built from (the utility's available fault current and X/R, transformer impedances, conductor impedances and lengths, motor and generator contribution, inverter-based sources, and the survey of existing equipment on a renovation), the source operating cases, the equipment duty evaluation, the treatment of series-rated combinations, the available fault current and date that NFPA 70 110.24 requires at the service equipment, the report and the model handed to the coordination and arc-flash studies, and the events that call for a re-study.

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