Ensuring the safety and reliability of electrical installations demands meticulous fire-prevention and explosion-mitigation measures. Each category of equipment—whether transformers, cables, motors, or lighting systems—has its own inherent hazards. Through disciplined operations, preventive maintenance, and adherence to engineering regulations, these risks can be significantly curtailed. The following guidance outlines essential practices for safeguarding widely used electrical devices.

I. Fire and Explosion Protection for Transformers

Routine vigilance is indispensable. Operators must intensify real-time monitoring and perform scheduled patrol inspections, recording operational data with precision. Under normal conditions each shift should conduct at least one to two checks; during severe weather or overload operation, inspection frequency must be increased.

Close attention is required for oil temperature, oil coloration, and internal acoustic signature. Abnormalities—whether sudden noise, discoloration, or rapid temperature rise—should trigger immediate intervention. The upper-layer oil temperature should remain below 85°C to prevent thermal degradation and potential ignition.

Transformer protective relays must remain in impeccable order. Reliable, selective tripping during faults prevents secondary damage and mitigates cascading failures. Continuous oversight of load conditions is vital. Overloading beyond prescribed limits is strictly prohibited.

Scheduled maintenance ensures long-term stability. Minor overhauls are typically conducted annually, while major overhauls occur every five years. Before the thunderstorm season, all lightning-protection apparatus must be inspected and tested, ensuring the substation’s surge-resistance capability remains robust.

Firefighting apparatus must be abundant, well-distributed, and periodically replaced. Oil barrels and flammable substances cannot be stored inside transformer rooms or substations.

II. Fire and Explosion Protection for Oil Circuit Breakers

The switching capacity of an oil circuit breaker must match the short-circuit capacity of the electrical system it serves. Design and installation must follow regulatory standards. These breakers should be installed inside fire-resistant structures with adequate ventilation. Indoor oil breakers must be isolated within non-combustible compartments equipped with oil-retention features, while outdoor units require gravel-based oil collection pits.

Operation and maintenance practices must be rigorous. Patrols should be intensified during heavy loading, after every automatic trip, and during adverse weather to ensure that the operating state remains well understood. The oil level must remain within its designated limits, and inspections should detect leaks, contamination, cracked bushings, or abnormal discharge sounds.

Preventive testing is mandatory. Oil quality must meet specifications, and deterioration requires immediate replacement. Annual dielectric tests and simplified inspections are required, with laboratory sampling after every short-circuit trip.

Both minor and major repairs must be performed as scheduled—small repairs once or twice a year and major repairs every three years. Following a fault trip, the breaker must not be dismantled immediately; residual gases within the oil must be allowed to dissipate and cool before any maintenance begins.

III. Fire and Explosion Protection for Power Capacitors

Power capacitors should preferably include internal fuses for independent protection. Units lacking this feature must be safeguarded through group fusing or dedicated protective arrangements—such as zero-sequence current balancing for double-Y configurations or transverse-differential protection for double-delta connections.

Modern low-loss, long-life, self-healing capacitors with flame-retardant housings and integrated pressure-release devices provide superior safety. Their ability to restore insulation after minor internal breakdowns significantly reduces catastrophic failure risks.

Operational monitoring must be systematic. Staffed substations should inspect at least once per shift; unattended stations require weekly checks. Voltage, current, ambient temperature, noise, odors, bushing cleanliness, flashover marks, oil leakage, and capacitor bulging must be observed without exception.

Operating limits must be strictly enforced:

• Current should not exceed 1.3 times the rated value.

• Voltage should not surpass 1.05 times the rating, except for short periods (up to 4 hours at 1.1 times).

• Ambient temperatures must remain within –25°C to 40°C, with enclosure temperatures below 55°C and hotspot temperatures ideally under 60°C.

• Re-energization is prohibited before a 3-minute discharge interval has elapsed.

• Porcelain bushings must not be used as lifting points during transport.

Capacitor rooms should meet fire-resistance requirements (Class II for >1 kV, Class III for ≤1 kV). Cleanliness and ventilation must be maintained, and fire-suppressing agents such as sand or carbon-tetrachloride equipment should be positioned nearby.

IV. Fire and Explosion Protection for Power Cables

Cable installation must adhere strictly to engineering specifications to prevent mechanical stress and insulation damage. Horizontal routing should be used whenever feasible to minimize elevation differences.

Cable terminations and joints must be fabricated according to standards and verified through testing. Continuous monitoring during operation is essential; prolonged overloading must be avoided. Routine cleaning, insulation checks, and preventive testing ensure prolonged cable health and reduce thermal-runaway and ignition risks.

V. Fire and Explosion Protection for Low-Voltage Distribution Panels

Low-voltage panels, cabinets, and boards must be constructed from fire-resistant materials. Timber-based assemblies require metal cladding or fire-retardant coating. Outdoor panels must incorporate weatherproofing.

Equipment selection must correspond to system voltage, load characteristics, and fire-safety requirements. Components should be securely mounted, and switch ratings must satisfy feeder and main-bus demands.

Wiring should use fully insulated conductors arranged neatly and bundled securely. Crossings should be minimized, and insulated sleeves must be applied where crossings are unavoidable. Routine insulation-resistance measurements help detect faults early; defective sections must be replaced promptly.

All metallic frames and enclosures require reliable grounding or neutral protection.

VI. Fire and Explosion Protection for Low-Voltage Switches

Switch selection must match environmental conditions. Hazardous or explosive atmospheres require explosion-proof switches; chemical or fire-risk environments require specialized designs.

Knife switches must be installed on non-combustible substrates. Adequate clearance from flammable materials prevents ignition from switching sparks. Insulating barriers should separate phases to avoid inter-phase short circuits.

All conductor terminations must be tight with excellent contact quality to avoid overheating. Smaller loads may use porcelain-based knife switches; dusty or damp locations should employ metal-enclosed switches; high-capacity loads require automatic air switches.

Switch ratings—voltage, current, and breaking capacity—must match system demands. Automatic switches must be cleaned and inspected frequently to prevent flashover, dust accumulation, or explosion risks.

In grounded-neutral systems, single-pole switches must be placed on the live conductor only. Explosion-proof switches must be cleaned of preservative grease before use; machine oil should be applied instead, as grease can release explosive gases under arcing conditions.

VII. Fire and Explosion Protection for Electric Motors

Motor selection must match the hazard level of the environment. Explosion-proof motors are mandatory in areas containing flammable gases or vapors. Motors must never be installed on combustible supports, and nearby areas must remain free from flammable storage.

Installation quality must be impeccable. Connections at terminal boxes must be securely fastened. Proper grounding or neutral bonding is mandatory.

Each motor requires an independent operating switch. Fuse and thermal-overload protection must be correctly rated. For large or critical motors, phase-loss protection is recommended.

Routine inspections must monitor current, voltage, temperature rise, cooling airflow, and abnormal noise. Periodic minor and major maintenance ensures long-term stability. Insulation resistance must meet minimum standards: 0.5 MΩ for low-voltage motors and 1 MΩ per kV for high-voltage motors.

Excessive start frequency must be avoided to prevent overheating; cold-state starts should be limited to 3–5 per minute, and hot-state starts to 1–2 per minute.

VIII. Fire and Explosion Protection for Lighting Fixtures

Lighting fixtures must be selected according to the environmental hazard. Explosion-prone locations require dedicated explosion-proof luminaires. Open-type fixtures belong only in dry, non-corrosive, non-flammable atmospheres; damp areas require moisture-proof fittings; outdoor applications need weatherproof enclosures.

Wiring must be properly rated, insulated, and installed to prevent crossed circuits. Joints should be minimal and meticulously insulated to prevent sparks from loose connections.

Adequate clearance must be kept between lamps and combustible materials. Nothing combustible should be stored beneath fixtures where falling glass or hot fragments could ignite materials.

Halogen lamps demand special caution. Their quartz envelopes can reach 500–800°C, making them unsuitable for storage rooms holding combustible goods.

Ventilation of fixtures is essential, particularly recessed housings. Heat-dissipation paths must never be obstructed, and at least 100 mm of clearance around recessed installations is recommended.

For low-voltage lighting, conductor cross-sectional area must accommodate the increased current. Fluorescent and mercury-lamp ballasts must not be attached to combustible structures.

Damaged fixtures must be repaired or replaced immediately, and large-wattage lighting should be switched off whenever illumination is unnecessary.

IX. Fire and Explosion Protection for Fuses

Fuse elements must be properly rated; oversizing or replacing with copper wire is dangerous and strictly forbidden. Fuse selection must match environmental hazards—explosive atmospheres require sealed housings or specialized explosion-proof designs, and fuses should be installed outside hazardous zones whenever possible.

Fuses located on incoming feeders, branch circuits, or equipment must have securely fastened terminals with adequate contact pressure. High-current fuses should be mounted on heat-resistant substrates such as porcelain or stone; enclosures must never use combustible materials.

Combustible clutter must not be stored near fuse assemblies. Periodic cleaning and timely replacement of damaged components ensure operational safety.

X. Fire and Explosion Protection for Electric Heating Equipment

Facilities using electric heaters must install master disconnect switches and fuses. High-power heaters require dedicated switching devices, as plug connections can produce arcing during insertion or removal.

Supply conductors must support the heater’s full current demand; rubber-insulated wires are prohibited. Heaters must be placed on non-combustible surfaces and kept away from flammable materials. In areas containing flammable gases, vapors, or dust, electric heaters are not permitted.

Continuous supervision is mandatory. Operators must remain present during operation, and power must be cut before leaving the area. Equipment must cool down or be otherwise safeguarded before the operator departs.

Routine maintenance is essential. Before use, wiring integrity, insulation, switches, and fuses must be checked. Any component showing damage, aging, or degradation must be replaced immediately.