Class I, Division 1 locations have ignitible concentrations of flammable gases or vapors present during normal operations or due to leaks or faults.

NEC Article 460 covers the installation of capacitors on electrical circuits, excluding surge capacitors or those part of other apparatus conforming to specific requirements.

Article 470 covers the installation of separate resistors and reactors on electrical circuits but does not apply to those integrated into other equipment.

Constant-voltage generators must be protected from overload using any of the listed methods, depending on the conditions of use.

Overcurrent protection for transformers over 1000 volts must follow Table 450.3(A), considering factors like location and impedance.

Modified transformers must be marked to show the type of insulating liquid installed to ensure proper identification and compliance with NEC requirements.

Article 445 applies to the installation and requirements of all generators, including stationary and portable units used in various applications.

Conductors must have insulation rated for at least 90°C (194°F) to handle the heat generated by resistance elements, ensuring safe operation.

Minimum air separation between live parts depends on voltage, as outlined in Table 495.24, to ensure safety and functionality.

Switchgear frames and related equipment must be grounded in accordance with Article 250 to prevent faults and ensure safety.

Substations must be designed by a licensed engineer, with documentation covering clearances, grounding, fire protection, and other critical aspects to meet NEC requirements.

Minimum wire-bending space at transformer terminals for systems below 1000 volts must comply with NEC 312.6 requirements.

Vaults must be ventilated to ensure transformer full-load heat losses are disposed of without exceeding the transformer’s temperature rating.

Antioxidant materials must be used where dissimilar metals meet, per the manufacturer’s recommendations, to prevent corrosion at battery connections.

Resistors and reactors must maintain a clearance of at least 12 inches from combustible materials or have a thermal barrier to prevent fire risks.

Stationary generators must be listed according to UL 2200, except for custom or one-ofa-kind units, which may be field-labeled.

Nameplates must include critical information such as manufacturer, voltage, frequency, power rating (kVA), and insulation type for compliance and safety.

Isolating means must fully disconnect all ungrounded conductors, ensuring that the equipment is de-energized for safe maintenance.

Conductors for variable loads must have an ampacity of at least 125% of the phase converter’s nameplate input full-load amperes to ensure safety during operation.

Single-phase loads must not be connected to the manufactured phase, as it is not solidly connected to the input and may cause instability.

A permanent sign must indicate backfeed hazards to prevent accidental contact with energized parts.

Ventilation openings must be covered with fire-resistant gratings or louvers and equipped with fire dampers to prevent fire spread while allowing adequate ventilation.

Vault doors must have a 3-hour fire resistance rating, which can be reduced to 1 hour if automatic sprinklers or equivalent systems are installed.

Indoor transformers rated 112.5 kVA or less must have 12 inches of separation from combustibles or be separated by a fire-resistant barrier to prevent fire hazards.

Less-flammable liquid-insulated transformers installed indoors must have a liquid confinement area and avoid combustible materials nearby.

Grounding autotransformers must have a continuous neutral-current rating and comply with Article 250 grounding and bonding requirements.

Capacitors must reduce their residual voltage to 50 volts or less within 1 minute of being disconnected from the power supply to ensure safety during maintenance.

Nameplates must include key information such as manufacturer, rated input/output voltages, frequency, full-load amperes, and load capacities in kVA or horsepower to ensure proper installation and use.

Article 495 applies to equipment operating at over 1000 volts AC or 1500 volts DC, covering installation and safety requirements.

Reconditioned resistors are not allowed to ensure reliability and safety, per NEC requirements.

A disconnecting means must disconnect all ungrounded supply conductors simultaneously and be located within sight of the phase converter for safe operation and servicing.

Doors to high-voltage compartments must be locked, and warning signs must be displayed to prevent access by unqualified persons.

Generator nameplates must include critical data such as manufacturer, rated frequency, power factor, and rated amperes to ensure proper installation and safety.

Capacitors with more than 11 liters of flammable liquid must be installed in vaults or outdoor fenced enclosures to prevent fire hazards, in accordance with Article 110.

Battery rooms must have illumination for working spaces, and the lighting must not depend solely on automatic controls to ensure safety during maintenance.

Ventilation must ensure explosive gases like hydrogen do not accumulate, even if achieved through natural airflow, to maintain safety.

Outdoor dry-type transformers must have weatherproof enclosures to ensure safe operation in various environmental conditions.

Overcurrent protection is not required for battery conductors under 60 volts DC used for starting, ignition, or control of prime movers, simplifying their installation.

Indoor oil-insulated transformers must be installed in a vault unless specific exceptions, such as size or voltage limits, apply.

Generators above 15 kW must include a remote emergency stop switch located outside the equipment room or generator enclosure for safety.

Sealed cells must have pressure-release vents to address any excessive pressure that could develop during operation.

If no disconnecting means is present, markings must include nominal voltage, available fault current, and an arc flash label, ensuring compliance with safety requirements.

Article 480 applies to stationary standby batteries with a capacity greater than 3.6 MJ (1 kWh), excluding smaller installations.

Article 455 applies to both rotary and static phase converters used to convert singlephase power to three-phase power for equipment operation.

Vault walls must have a minimum fire resistance of 3 hours unless equipped with automatic fire suppression systems, which allow for reduced ratings.

Capacitor cases must be connected to the equipment grounding conductor unless specifically designed to operate at other than ground potential, ensuring electrical safety.

Resistor and reactor cases must be grounded to the equipment grounding conductor unless they are specifically designed to operate at non-ground potential.

Transformers require a disconnecting means that is either in sight or lockable if remotely located, with its location field-marked on the transformer.

Mechanical interlocks are required to ensure that stored energy mechanisms are discharged or blocked before access to the switch compartment is allowed.

Capacitor circuit conductors must have an ampacity not less than 135% of the capacitor’s rated current to handle potential current increases due to manufacturing tolerances and voltage variations.