Summary:The article outlines the primary causes of electrical fires in medical institutions, using a specific hospital as an example. It delves into the hospital's preventive measures against electrical fires from six aspects: the quality of electrical engineering construction, the quality of electrical products, management of electrical power usage in construction, departmental power usage management, power system operation management, and management of the demand side of electricity.
Keywords:Hospital; Electrical Fire; Preventive Measures;
1. Introduction
Based on the statistical analysis of electrical fire accidents in public buildings, there were a total of 87 fires from 2000 to 2018 in China that resulted in three or more fatalities, causing 1,389 deaths. In 2016, 47.5% of fires in medical institutions nationwide were caused by electrical issues. Looking at past cases of electrical fires in hospitals, cable problems, equipment failures, and illegal construction are the primary causes. From the analysis of public building electrical fires, the main factors include electrical failures, human factors (illegal operations), wire aging and short circuits, poor contact of conductors, and electrical equipment igniting other flammable materials. Hospitals should address the causes of electrical fires, implement effective management measures, eliminate hazards, prevent electrical fire accidents, and ensure the normal conduct of medical work.
Electricity Overview at Hospital 2
Our hospital, a comprehensive, three-level A-grade tumor specialty hospital integrated with clinical, scientific research, and teaching, spans an area of 200,000 m2 and consists of 15 buildings. The power supply system has a total capacity of 20,200 kVA, comprising one main high-voltage switchgear room and three branch high-voltage switchgear rooms, with a total of 12 transformers. Two external power sources enter the hospital, passing through multiple stages including high-voltage distribution, transformer voltage reduction, low-voltage distribution, cable transmission, secondary or tertiary distribution, and further cable transmission before reaching the electrical terminals. With numerous power supply stages and diverse electrical load scenarios, each stage and different electrical use scenario poses potential power supply hazards. In the event of an electrical fire, it could disrupt patient treatment and diagnosis activities, and in severe cases, it could threaten patient lives. 3 Analysis of Electrical Fire Causes
(1) Electrical Engineering Quality
The primary factors affecting electrical engineering quality are materials and construction. Poor cable quality is mainly manifested as: conductor cross-sectional area smaller than the rated area, and substandard copper material in the conductors, which result in the cable's rated current not meeting requirements, causing the cable temperature to rise during use; most cables are installed in concealed conduits with poor heat dissipation conditions, which easily lead to fires. Most electrical conduits are made of metal, and if the joints or bends are not properly handled during installation, burrs can form, making it easy to damage the insulation of the wires during installation, causing leakage and short circuits, which in turn can trigger fires; in distribution panels and cabinets, if the screws connecting circuit breakers, relays, contactors, and leakage protectors to the conductors are not tightened, the contacts will heat up when current passes through, leading to increased temperature over time, damaging the insulation and causing short circuits.
(II) Electrical Appliance Product Quality
Counterfeit electrical products are highly prone to causing fires, especially small medical electrical equipment, lighting facilities, various electrical components, charging devices, and more.
(3) Construction Power Management
An external unit was conducting various construction projects at the hospital without properly configuring temporary electrical facilities, illegally connecting wires, and failing to install leakage protection devices. The personnel lacked awareness of electrical safety and those without electrical operator qualifications violated regulations by operating construction equipment, ultimately causing an electrical fire accident.
(4) Departmental Electricity Management
Computers, printers, refrigerators, microwaves, and other equipment used in patient rooms and offices, as well as low-temperature freezers and various scientific instruments used by research teams, were not properly wired according to specifications. Multiple extension cords were串联ed, with mismatched plugs and sockets, resulting in poor contact. After prolonged use, the sockets smoked or were damaged. The insulation on the power cords of the equipment was damaged, and papers, books, and debris were piled around the appliances, obstructing heat dissipation and causing electrical faults, igniting nearby flammable materials. Improper charging management of devices with rechargeable batteries led to battery fires and accidents.
(5) Power System Operation and Management
Failure to conduct high-voltage preventive tests as required, uncalibrated protective settings; power supply equipment operating with latent hazards, declining insulation performance of transformers and power cables; operators' non-compliant actions, incomplete emergency response procedures; substandard insulating tools or lack of regular inspections; personnel lacking qualifications for duty; and irregular labor protection measures—all these factors are prone to cause electrical fire accidents.
(Six) Management of electricity demand side
The hospital has not reasonably planned the distribution of electrical load among its facilities, leading to high transformer loads during peak electricity consumption periods. Each year, the hospital adds or replaces large equipment, but lacks knowledge about the rated power, voltage, and current, peak power, starting current, power factor, and harmonic interference of the new equipment. If the selected low-voltage distribution switches fail to meet the usage requirements, it poses a hidden danger of electrical fires for future use.
4 Effective Measures to Prevent Electrical Fire Accidents
Electrical engineering construction and renovation
Typically, electrical engineering projects and renovations can be used for over 15 years. The quality of electrical engineering is crucial to the safety of the entire power supply system. Comprehensive planning is required for the capacity of the power supply system, the selection of medium and low-voltage distribution cabinets, the choice of cables and routers, the setting of the rated current for the circuit breakers in the power supply system, and the assurance of emergency power supply capabilities, all to ensure safe power supply and meet the needs of clinical, research, and educational activities. To ensure the safe and effective operation of the power supply system, the following aspects should be given special attention in electrical engineering construction and renovation.
Firstly, the electrical engineering must be entrusted to a design unit with professional qualifications. The institute will accurately provide the design unit with the electricity demand and parameters of various loads. It should consider the load capacity required for future equipment additions, leave sufficient redundancy in the design, and meet future electricity demands.
Secondly, upon the arrival of electrical components used in electrical engineering, the contractor, construction party, and supervisory party must jointly inspect the goods. The inspection includes product appearance, model, and quantity, factory certification, 3C product certification, cable test reports, etc. It is necessary to check and tighten all screws before power is supplied to the distribution cabinets and boxes.
Thirdly, the power cables used in the project are mostly installed in concealed ways, either laid in cable trays indoors or in cable trenches outdoors, or buried directly. Once installed, the service life of power cables typically exceeds 10 years, with some even lasting over 20. The presence of heat or potential hazards in the cables during use is not easily detectable, making quality-assured power cables crucial. Approximately 80% of power cables are made of copper material. Some manufacturers, in pursuit of high profits, reduce the cross-sectional area of the conductors by using copper with impurities, which lowers the cable's current-carrying capacity. When the circuit load increases or the environmental temperature rises, the cable temperature can escalate, accelerating the aging of the cable insulation. In severe cases, this can lead to power line leakage, short circuits, and even fire accidents. Upon arrival, the manufacturer should be required to provide a quality inspection report for the batch of cables. On-site sampling of the cables should also be conducted, and a re-inspection should be entrusted to a CMA (China Metrology Certification) accredited testing institution. The re-inspection primarily focuses on the conductor resistance value and cross-sectional area. Table 1 presents the test values of the 180m cable (model: ZRC-YJV22-4×70+1×35) purchased for the power engineering project, which were only approved after passing the inspection before the laying work could commence.
Fourthly, when pre-installing electrical wires in walls, first lay the conduit, then run the wires through. Metal conduits can develop burrs at corners or joints, which can damage the insulation during wiring, leading to reduced insulation performance. Post-installation, due to factors like moisture, this can cause phase-to-ground short circuits. Therefore, it's essential to smooth the metal conduit openings with tools like files to ensure they are burr-free before wiring. This prevents damage to the wire's insulation. After the wiring is completed, insulation tests must be conducted, including phase-to-phase, phase-to-ground, and phase-to-neutral insulation. Only after the insulation resistance meets the requirements should power be applied to prevent short circuit accidents.
Fifth, within the hospital's electrical system, from the low-voltage switchgear in the distribution room to the electrical loads, there must be a three-level or higher transmission of low-voltage power distribution. From the supply end to the load end, the current setting value of the circuit breakers must be progressively reduced to prevent lower-level switches from short-circuiting and causing a cascading trip.
Electrical products and electrical components purchased must have the China Compulsory Certification (CCC), also known as the 3C Certification.
When making bulk purchases, it is essential to verify the qualifications of the manufacturing enterprises, product certificates, various inspection documents, and product test certificates to ensure product quality and to prevent the purchase of unauthorized, counterfeit, label-switched, or fake and inferior electrical products and components.
(3) Construction Power Management
Firstly, the construction site must have safety management regulations and systems for electrical use, and electrical workers must hold valid electrician operation certificates and strictly adhere to all electrical safety operation procedures.
Secondly, temporary electrical power at construction sites should use a three-phase five-wire system. The main cables should be five-core cables, indoor wiring should use insulated conductors, and the metal shells of electrical equipment must be connected to the protective zero line. The electrical equipment such as power cables, motor tools, lighting equipment, etc., prepared by the construction unit should have good performance and comply with safety technical specifications.
Thirdly, the contractor shall submit the total electricity demand to the hospital's administrative department. The hospital is responsible for designating the power switch wiring locations for the contractor and is prohibited from arbitrarily pulling and connecting electrical wires.
Fourth, the construction unit should set up a main distribution box and sub-distribution boxes, as well as switch boxes for the power distribution system, implementing分级配电 with strict adherence to the "one machine, one box, one switch" system. The switch boxes should be equipped with residual current protectors, with a rated leakage current not exceeding 30mA and a rated leakage time not exceeding 0.1 seconds, ensuring the protection device is intact and effective.
Fifth, temporary lighting facilities in humid environments should use voltages below 36V, and there should be a designated person supervising when using handheld electric tools.
Sixth, upon entering the construction site, the contractor should sign the "Electric Safety Agreement" with the hospital's construction department.
(4) Departmental Electrical Safety Management
Firstly, each department must appoint several electrical safety managers, dividing their responsibilities according to the work area. Electrical safety managers conduct a weekly inspection of the areas they are responsible for, primarily checking for adequate ventilation around electrical equipment, proper heat dissipation, the presence of flammable or explosive items, humidity levels, and any unauthorized operations of electrical equipment. After work hours, they must disconnect the power supply to unused electrical equipment. They also inspect the wires, plugs, and outlets of electrical equipment for damage and report any issues promptly for repair.
Secondly, we have established a WeChat group for electrical safety managers, including departmental electrical safety managers, power system operators, professional maintenance staff, and security personnel. If any electrical hazards are discovered, they can be reported in the group at any time, enabling a quick response to eliminate the hazards in their nascent stage. Our hospital set up this group in 2017, and it currently has 225 members, effectively serving as a preventive measure.
Third, there are many power outlets in the hospital office space, and counterfeit power outlets pose safety hazards. The hospital should purchase new standard power outlets with 3C certification in a unified manner; the installation of power outlets must be standardized, they should be hung vertically, not placed directly on the ground or table, and should not be used in series; they should not be used for electrical equipment above 2000W.
Fourthly, charging of various rechargeable vehicles and high-power electrical appliances is prohibited in office spaces, especially personal electric vehicles. For charging equipment required for hospital operations, a detailed charging management system must be established, with a designated person in charge and supervised by an electrical safety manager. Personal electrical equipment purchased by individuals is not allowed to be used in the hospital.
Fifth, conduct regular training for electrical safety management personnel, covering topics such as laws and regulations, electrical safety, inspection methods,隐患 disposal, and incident reporting. The hospital conducts inspections before holidays and major events to check if the inspection records of the departmental electrical safety management personnel are complete and if the contents of the inspections are accurate.
(5) Power System Operations Management
Firstly, personnel responsible for the operation and maintenance of the power system should hold a valid electrician's operation certificate, properly wear protective gear upon duty, and be familiar with the types, placement, applicable scope, and usage of fire extinguishers.
Secondly, the power system operation and maintenance personnel must be familiar with the hospital's power supply system, particularly the grading of the hospital's electrical load and the operational status of the emergency load. The hospital's electrical load is categorized into three levels: Level 1, Level 2, and Level 3, with Level 1 including especially critical loads. As a specialized cancer hospital, our Level 1 critical loads are the operating rooms and ICU; Level 1 also includes the fire protection system, fire elevators, security system, control room, information room, and emergency lighting; Level 2 includes large medical equipment, testing and biochemical equipment, wastewater stations, and medical gas stations; the rest is classified as Level 3. The operation and maintenance staff should be knowledgeable about the power supply from the substation to the electrical terminals for Level 1 and Level 2 loads, and should be able to quickly address electrical accidents.
Thirdly, comprehensive power supply system documentation is essential. Our institute has four high-voltage switchrooms, each with different medium-voltage switchboards, low-voltage switchboards, transformers, generators, and DC screens due to varying construction years. The technical documentation is scattered, making it difficult to locate information when needed. Therefore, it is necessary to organize and compile the technical documentation of the power system into a comprehensive set, including the models of switchboards, switch brands and models, current transformers (CT) and voltage transformers (PT) ratio; types and ratios of 10kV relay protection, operating voltage and current, and operating time; transformer brands, models, capacity, manufacturer, and date; location information of low-voltage outgoing lines, cable models, and lengths, etc. Once compiled into a manual, it becomes easier to access and utilize the information.
Fourth, master the load regulations (load classification), and be aware of each transformer's annual load conditions, particularly the transformer load rate during the peak electricity consumption period in summer. Ensure the ability to operate in the N-1 mode at any time. If not feasible, have a load reduction plan in place. In emergency situations, shut off the power supply to some third-level loads to guarantee the power demand for first and second-level loads.
Fifth, establish an emergency response plan tailored to the hospital's specific circumstances. The plan should include six types of switch-displacement methods: two 10kV external power sources feeding the entire station, and one 10kV external power source feeding the entire station through a tie switch. It should also cover scenarios such as one or two 10kV external power sources being out of power, out-of-level tripping, instantaneous current interruption protection, zero-sequence grounding overcurrent protection, and emergency response to power supply accidents. This ensures timely handling of power supply accidents and reduces the risk of electrical fires.
Sixth, components within distribution cabinets and boxes are prone to loose connections, which can lead to contact resistance and increased temperature over time, potentially causing smoke and damage. Regularly use an infrared thermometer to test the temperature of the main components' connections in distribution cabinets; address any abnormal temperatures promptly. Conduct an annual infrared temperature measurement of all distribution cabinets to detect internal operating temperatures of components, enabling early detection of safety hazards and preventing electrical fires.
Every two years, conduct high-voltage preventive tests, including insulation and withstand voltage tests on the 10kV busbars; insulation and withstand voltage tests on 10kV switchgear, switch operating mechanism operation tests; insulation and withstand voltage tests on 10kV cables; insulation and withstand voltage tests on transformers; relay protection setting tests, including overcurrent, rapid-break, and zero-sequence operation tests, etc.
(Six) Demand-Side Management of Electricity Consumption
The hospital's electricity authority must coordinate the entire hospital's electricity load capacity, endeavoring to predict the growth in electricity load as early as possible, ensuring safety for subsequent electricity operation management.
Firstly, the hospital's electricity consumption is primarily in HVAC, medical equipment, lighting, etc. If the total transformer capacity of the hospital's power supply can reach 100VA/m2 of floor area, it can generally meet the hospital's electricity needs. While ensuring the electricity capacity, it is necessary to reasonably distribute the power load to ensure safe power supply.
Secondly, in situations such as purchasing new equipment, migrating existing equipment, temporary construction power supply, and building renovations, an electricity application must be submitted in advance. The application should be completed on the "Electricity Demand Application Form," which includes details such as the location of use, rated power, peak power, rated voltage and current, and the expected start-up time. The power operation management department will plan accordingly to meet the electricity needs.
Third, if the power consumption is less than 30kW, power supply solutions can be implemented within one week to meet the power requirements; however, for power consumption exceeding 30kW (including devices like MR and accelerators with power over 100kW), a power supply plan is necessary, and at least three months should be reserved for capacity expansion work. In our hospital's改造 of three high-voltage switchgear rooms, over 40 standby outgoing circuit breakers have been reserved, particularly 400A and 630A circuit breakers, to ensure a well-planned power distribution for future hospital development. Power demand-side management has been in place at our hospital for four years and has achieved excellent results. Table 2 shows the power demand applications over the past four years at our hospital.
Please tally.
Ankore Electric's 5th Generation Fire Monitoring System
(1) Overview
The Acre1-6000 Electrical Fire Monitoring System has been certified by the central fire product testing and certification center, and all have passed rigorous EMC electromagnetic compatibility tests, ensuring safe and stable operation of the series in low-voltage distribution systems. It is now in mass production and widely used across the nation. The system collects and monitors signals such as residual current, overcurrent, overvoltage, temperature, and fault arcs, enabling early prevention and alarm for electrical fires. It can also disconnect the distribution circuits with excessive residual current, temperature, and fault arcs upon need. Additionally, it can meet the requirements for data exchange and sharing with the AcreIEMS corporate microgrid management cloud platform or fire automatic alarm systems, as per user needs.
Application Scenario
Ideal for smart buildings, high-rise apartments, hotels, restaurants, commercial complexes, industrial and mining enterprises, key fire protection units, as well as the oil and petrochemical, cultural and educational, health, financial, and telecommunications sectors.
(3) System Architecture
(System Features)
The monitoring equipment can receive residual current and temperature information from multiple detectors. When an alarm is triggered, it emits both audio and visual alarm signals. Simultaneously, the red "ALARM" indicator light on the device illuminates, the display indicates the alarm location and type, records the alarm time, and the audio-visual alarm continues until the "RESET" button on the device or the "RESET" key on the touch screen remotely resets the detector. The audio alarm signal can also be manually silenced using the "Mute" key on the touch screen.
Upon alarm from the monitored circuit, the control output relay closes to control the protected circuit or other equipment. Once the alarm is cleared, the control output relay releases.
Communication Fault Alarm: When a communication failure occurs between the monitoring equipment and any connected detector, or when the detector itself fails, the corresponding detector on the monitoring screen will display a fault prompt. Simultaneously, the yellow "FAULT" indicator light on the device will illuminate, and an alarm sound will be emitted. Power Fault Alarm: In case of a power failure in the main or backup power supply, the monitoring equipment will also emit an audio-visual alarm signal and display fault information. Users can access the corresponding interface to view detailed information and deactivate the alarm sound.
In the event of residual current, over-temperature alarms, communication or power failures, the alarm location, fault information, and alarm time are stored in the database. Similarly, records are kept when the alarm is lifted and the fault is rectified. Historical data offers various convenient and quick methods for querying.
5 Conclusion
Our institution has formulated detailed management regulations and preventive measures across six aspects: electrical construction quality, electrical product quality, construction power management, departmental power management, power system operation management, and power demand-side management. We have also established and improved reward and punishment mechanisms, conducted regular inspections of the implementation of regulations and rules, and eliminated potential electrical fire hazards at their inception, effectively preventing electrical fire accidents. As the hospital continues to grow and electrical equipment and facilities are constantly updated, preventing electrical fires will be a long-term and ongoing process. It is crucial to strictly enforce existing systems and continuously improve management regulations in line with changes. We should fully utilize electrical fire alarm monitoring systems to ensure the safety of the hospital's power system, guaranteeing the normal conduct of medical, teaching, and research activities.
Reference
- Ankore Corporation Microgrid Design and Application Manual, 2022.5 Edition
- Zhao Zhiquan. Statistical Analysis of 49 Hospital Warehouse Fires in Mainland China from 2000 to 2019[J]. China Hospital Architecture and Equipment, 2020, 21(9): 127-128.
- Chen Pingle. Analysis of Causes and Preventive Measures for Electrical Fire Accidents in Construction [J].低碳世界, 2020, 10(11): 225-226.
- Ma Qi. Analysis of the Cause and Rectification Measures for an Electrical Fire Accident in a Hospital in Guangzhou[J]. China Hospital Architecture and Equipment, 2016(12): 100-102.
- Wang Jianjia, Wang Bin, Zhu Jinguo, Hu Jianhua, Wang Zheng, Wang Dongwei, Zhang Jiasen, Cai Jianqiang, Cheng Yong. Measures for Preventing Electrical Fires in Hospitals
