Firefighting Power Supplies as Emergency Backup Sources (UK)
Purpose and Importance in Life Safety
Firefighting power supplies serve as dedicated emergency backup sources for critical building systems that protect life during a fire or other emergency. In high-rise residential and commercial buildings, these backup power systems are fundamental to safeguarding occupants and assisting firefighters. They ensure that essential safety installations – from fire-fighting lifts to alarms – remain operational when the mains power fails . In effect, the integrity of the backup electrical supply can be a matter of life and death, preventing darkness, communication loss, or equipment failure during evacuations. By keeping life safety systems running in a power outage, firefighting power supplies uphold safe evacuation for residents, enable critical fire-fighting operations, and help meet legal life safety requirements.
Typical Emergency Power Sources
Secondary power supplies are typically provided by either an on-site emergency generator or a totally separate electrical feed, independent of the building’s normal mains supply. For example, British Standards recommend that an independent backup source – “e.g. an automatically started generator or a supply from another substation” – be in place to maintain life safety equipment if the primary power fails. In some cases, large buildings may arrange a secondary feed from a separate utility grid substation, so that if one substation is down the other can supply essential loads. More commonly, especially in high-rises, a diesel generator set is installed as a standby power source. This generator is automatically started upon loss of mains and is sized to support worst-case fire emergency loads (including motor startup surges for pumps, fans, etc.). For less power-intensive needs or for instantaneous switchover, Uninterruptible Power Supplies (UPS) or central battery systems (complying with EN 50171) may also be used to provide no-break power. However, UPS systems are typically used only for short-duration backup or in specific scenarios (such as lighting or control equipment) – any UPS intended for life safety must be appropriately rated and capable of handling inrush currents (e.g. from lift motors) and the required duration. In all cases, the secondary source must have sufficient capacity and endurance to keep the critical life safety systems running for the required time period, which in large buildings is often at least 60 minutes and can be 2 hours or more. Hospitals and other major facilities often go even further – for instance, UK healthcare guidelines expect standby generators to have fuel for up to 96 hours of operation to ensure patient safety during prolonged outages.
Separation and Independence from Primary Electrical Systems
To ensure reliability during a fire, the emergency power infrastructure must be separated and fire-protected from the normal electrical systems of the building. This physical and electrical separation prevents a single incident from disabling both primary and backup supplies. In practice, each supply (normal and standby) is brought into a building via independent cables and pathways, which are adequately spaced apart or routed through low-risk areas so that a fire or fault cannot affect both simultaneously. The backup supply cables should ideally bypass the main building areas entirely – for example, BS 8519 recommends that high-voltage feeders for life safety systems enter directly into fire-rated switch rooms, rather than running through general building spaces. Any unavoidable sections of emergency power cabling that do traverse the building must be protected with fire-resistant construction (e.g. in 2-hour rated shafts or encased in fireproof material) to ensure circuit integrity is maintained during a blaze.
Key electrical components of the life safety power supply – such as the emergency generator, its switchgear, distribution boards for fire systems, and any associated control equipment – are typically housed in dedicated rooms or enclosures that are fire-compartmented from the rest of the building. Guidance in BS 9999 calls for any substations, plant rooms or enclosures containing life safety power equipment to be constructed to at least a 2-hour fire resistance standard. In high-rise design, it is common to locate the generator and firefighting electrical switchboard in a reinforced concrete plant room (or a fire-rated external enclosure) that can withstand fire for the required duration. This ensures the backup power remains operational even if the rest of the building is affected by flames.
Furthermore, the wiring for emergency circuits should be installed with fire-resistant cabling and supports. British Standard BS 8519 is a code of practice specifically for selecting and installing fire-resistant power and control cable systems for life safety and firefighting applications. It categorizes circuits by the survival time needed (e.g. 30, 60, 120 minutes) and recommends using cables and cable fixings that will continue to operate for those durations under fire conditions. In line with these recommendations, life safety cables (for lifts, smoke extract, etc.) in a high-rise are often specified to survive 120 minutes in fire (Category 3) for firefighting systems, and at least 60 minutes for evacuation and occupant safety systems. The primary and secondary supply cables must be clearly identified and segregated all the way to the point of use, with labels at switchboards indicating the presence of dual supplies. By keeping backup power infrastructure independent and hardened against fire, designers eliminate common failure points and ensure the secondary supply will be available when called upon.
Automatic Transfer Switches (ATS) and Changeover Equipment
An Automatic Transfer Switch (ATS) is the device that seamlessly switches critical loads from the normal supply to the emergency supply when a power failure occurs. The ATS continuously monitors the incoming mains. If the primary power fails or falls outside acceptable parameters, the ATS will automatically initiate the backup source and transfer the life safety loads onto it, typically within seconds. Speed and reliability of transfer are crucial. Standards guidance in the UK stipulates that the changeover to the secondary supply should happen within about 15 seconds of mains failure . This rapid response ensures minimal disruption – for instance, emergency lighting flicker is brief, fire alarms and ventilation systems continue operating, and fire-fighting lifts can be brought back into use quickly.
In high-rise and complex buildings, the ATS equipment itself must meet stringent criteria. BS 8519:2020 recommends that changeover devices conform to BS EN 60947-6-1 (the product standard for automatic transfer switching equipment) and that they use robust switch technology (classified as “PC” class switches) rather than simple contactor or circuit-breaker arrangements. In practice, this often means using a purpose-built ATS unit that integrates the sensing, controller, and switching mechanism in one tested assembly. The code explicitly states “The Automatic Transfer Switch (ATS) should be a single component with integrated controller from the same manufacturer.” to ensure the whole device is type-tested as one unit. This reduces the risk of integration errors and increases reliability during an emergency switchover. The ATS (and any associated bypass/isolation switches) should be installed in a fire-protected location – usually the same 2-hour rated room as the life safety switchboard or generator – so that it remains operational in a fire.
Another best practice, especially where continuous occupancy depends on life safety systems (such as in hospitals or very tall buildings), is to provide an ATS bypass arrangement. This typically involves a manual changeover or a second ATS in parallel, allowing the backup generator to be connected to loads directly during maintenance or ATS failure. BS 8519 recommends either a single or dual bypass so that the life safety circuits can still be powered while the primary ATS is being serviced. Overall, the ATS is a critical link that must itself be considered a part of the life safety system – it should be regularly tested and maintained, and designed such that any single point of failure is minimized.
Integration with Critical Life Safety Systems
Firefighting and backup power supplies are integrated with a range of critical life safety systems in high-rise offices, residential towers, and complex buildings. The intent is to keep these systems functioning during a fire or other emergency, even if normal power is lost. A UK life safety generator or secondary supply is expected to support all essential firefighting and evacuation equipment in the building. Below, we outline how key systems are supported:
Firefighting and Evacuation Lifts
Firefighters’ lifts (fire-fighting lifts) and evacuation lifts are specially equipped lifts intended for use during emergencies. Unlike standard passenger elevators, these lifts are required to have a dedicated emergency power supply as a distinguishing feature. In normal operation they run off the mains, but if mains power fails the lift’s ATS will automatically switch it to the backup supply (generator or secondary feed) without manual intervention. This ensures that firefighters can continue to use the lift to move personnel and equipment, and in the case of an evacuation lift, that persons with disabilities or mobility issues can be safely evacuated under management control.
Regulations underscore this requirement. BS 9999 (the fire safety code for building design) mandates that any lift used for evacuation or firefighting have an independent secondary power source. Typically, the backup feed for a firefighting lift will come from the building’s life safety generator. The wiring for the lift is arranged so that it is supplied through an ATS in the fire-fighting shaft or in a protected switch room, separate from the normal lift power supply. The lift is also designed to fail-safe in a predictable manner – for example, if power is lost and the backup fails to engage, the lift will return to a safe floor and open.
Firefighters’ lifts must also meet the product standard EN 81-72, which among other things requires that “a secondary back-up power supply” is available so the lift can operate for a specified duration during a fire. In practice, a generator dedicated to life safety will power not only the firefighters’ lift but also other emergency loads. If multiple firefighting lifts are present, each will be wired to the emergency supply. The capacity and response of the backup system must be sufficient to run all required lifts simultaneously with other critical loads (accounting for motor inrush currents). For evacuation lifts, similar principles apply – they are often fed from the same standby source. Notably, guidance allows that in some residential buildings an evacuation lift could be fed from a robust single incoming supply if no generator is available, provided all internal circuits are fire-protected to BS 8519 standards. However, in high-rise buildings with firefighting lifts or smoke control systems, a full secondary supply (generator or second intake) is required, which in turn covers the evacuation lift as well.
Smoke Control and Extraction Systems
Smoke control systems are vital for maintaining tenable conditions during a fire by venting smoke and heat from corridors, lobbies, and stairwells. These systems can include large mechanical smoke extract fans, smoke exhaust shafts with powered fans, stair pressurization fans, automatic opening vents (AOVs) on windows or shafts, and motorized smoke dampers. All such equipment that is expected to operate during a fire must have a reliable power supply even if mains power is compromised by the fire. Thus, smoke control and extraction equipment in high-rises are invariably connected to the emergency power supply.
For example, smoke extract fans used in basement car parks or in high-rise residential corridors are typically fed from the life safety generator. They often fall under the “fire-fighting systems” category, requiring at least 2 hours of operation in worst-case scenarios. BS 9999 specifically lists “smoke control system” and “pressurization fans (air supply and relief)” as systems that must have secondary power. This means the fan motors and their control panels need either an independent supply from a separate substation or, more commonly, a feed from the standby generator via fire-resistant cabling. The backup power must be able to start these large fans, which may entail considerable startup current; accordingly, generators are sized to handle the simultaneous start of a smoke extract fan and other loads.
Similarly, any staircase or lobby pressurization fans (which keep escape routes free of smoke by blowing fresh air in) are connected to the secondary supply. Automatic Opening Vents that open during a fire (such as rooftop smoke vents or window actuators) may be fail-safe (opening via spring upon power loss), but where they rely on motors, the backup supply or a battery is needed to ensure they can cycle open/closed as required. Smoke dampers in ductwork are usually fail-safe (closing on loss of power or via fusible link), so they often do not require an emergency power feed. However, any dampers that need to open for smoke extract or other active control will be wired to emergency circuits or have local backup power, since they must respond even during outages.
In summary, the entire smoke management system – from fans to control panels – is treated as part of the life safety electrical load. During a fire, these systems might run for an extended duration to assist firefighters after evacuation, so the cables and power must survive the fire conditions for as long as needed. They are integrated into the backup power network with appropriate priority to ensure smoke is reliably exhausted and escape routes kept clear, significantly improving life safety for occupants and assisting rescue operations.
Fire Detection and Alarm Systems
Fire alarm and detection systems are critical for early warning and orchestrating an emergency response. In the UK, fire alarm panels and detectors are normally required to have integral secondary power (sealed batteries) that can keep the system operational for at least 24 hours standby plus 30 minutes of alarm condition (as per BS 5839-1 for fire alarms). This battery backup ensures the fire alarm system functions independently of mains power. However, in large buildings, the fire alarm panel and any associated emergency communication systems are often also connected to the building’s standby generator or backup supply. This arrangement allows the batteries to be conserved and recharged, and it provides indefinite operation beyond the minimum battery duration. Indeed, life safety generators are typically designed to power “Fire Alarm Panels & Emergency Lighting” among other systems.
When mains power fails, the fire alarm will immediately switch to its batteries (no break). If a generator comes online within a few seconds, the fire alarm panel will then revert to using generator power (via its battery charger/power supply unit) automatically, thus preserving the batteries. This ensures continuous alarm coverage, sounders, voice alarm systems, and firefighter communication points remain active throughout the emergency. Any networked alarm or monitoring equipment (like graphics displays or auto-diallers) should also be on the backed-up supply. Additionally, fire detection systems in plant rooms (like sprinklers pumps or genset rooms) might need to remain powered to monitor conditions; therefore, the standby supply usually feeds the detection and control circuits for firefighting systems as well.
It’s worth noting that other life safety communications – for instance, the firefighters’ telephones/intercom system within a building (often found in fire-fighting lifts and refuge areas) – are also required to have secondary power. BS 9999 includes “fire-fighting intercommunications installations” in the list of systems needing backup power. These are commonly wired to the same standby supply or have battery units. In a high-rise building scenario, the reliability of the alarm and communication systems underpins effective evacuation and firefighter coordination, so integrating them with the emergency power supply (in addition to local batteries) is a widely adopted safety measure.
Emergency Lighting Systems
Emergency lighting provides illumination of escape routes, exits, and safety equipment during a mains failure. UK regulations (BS 5266-1) mandate that emergency lights come on within a fraction of a second of power loss and typically stay lit for a minimum duration (often 3 hours) on battery backup. In many buildings, each emergency luminaire has its own self-contained battery. In larger premises, there may be a central battery system (Central Power Supply System, CPSS per EN 50171) that supplies multiple light fittings. Regardless of design, these battery-backed lights will operate immediately when mains fails, ensuring occupants can see to evacuate.
However, it is common to also connect emergency lighting circuits to the building’s generator or backup supply if one exists. The generator does not replace the individual battery requirement (because there is a short start-up time for generators during which lights must stay on), but once the generator is running, it can supply the emergency lighting circuits and preserve the batteries. BS 8519 and BS 9999 treat emergency lighting as an essential service that should be fed from the life safety power supply alongside other systems. In practice, emergency lighting boards or central battery units are often wired to automatically receive power from the generator via an ATS or input contactor. This allows the emergency lights to recharge or to continue beyond their rated 3-hour window if evacuation and firefighting operations are still ongoing.
In high-rise buildings, the presence of backup power for lighting is especially important for prolonged incidents: stairwells and refuge areas may need illumination well past the initial evacuation. Hospitals, for example, will have extensive emergency lighting in operating theatres and wards, often backed by both UPS and generators to ensure no disruption. By integrating emergency lighting with the standby power supply (while still maintaining local battery packs for instantaneous illumination), designers add resilience through redundancy. The lights will come on immediately on batteries and then can be sustained indefinitely on generator power. This dual approach meets life safety code requirements and provides greater assurance of illumination during a lengthy emergency scenario.
Compliance and Standards
Design and installation of firefighting and emergency power supplies in the UK must comply with a network of British Standards and regulations. Below is an overview of key standards and their relevance:
BS 8519:2020 – Fire-Resistant Power Systems Code: Selection and installation of fire-resistant power and control cable systems for life safety, firefighting and other critical applications. This code of practice provides comprehensive guidance on designing secondary power supplies, including recommendations for cable ratings, routing, and protection, as well as guidance on backup generators and transfer switches. BS 8519 introduced fire survival time categories (30, 60, 120 minutes) for circuits to ensure critical equipment continues to operate during a fire. It also specifies that components like the ATS should meet certain standards and be in fire-proof enclosures, and gives guidance on fuel storage for generators (e.g. minimum 4 hours fuel if only used in fire conditions, 8 hours if also used for general standby).
BS 9999:2017 – Code of Practice for Fire Safety in the Design, Management and Use of Buildings: This standard is a broad fire safety code and includes specific recommendations for backup power. It essentially requires a “secondary power supply… independent of the primary supply” for all critical fire protection systems. BS 9999 lists which systems should have secondary power (including sprinkler pumps, wet riser pumps, firefighting lifts, smoke control and pressurization systems, evacuation lifts, fire alarm systems, etc). It also cross-references BS 8519 for how to achieve separation and fire protection of these power supplies. For timing, BS 9999 recommends the backup supply activate within 15 seconds of mains failure for life safety loads. Compliance with BS 9999 is often needed to satisfy building regulations and fire authorities that the design provides adequate life safety.
BS 9991:2015 (and 2023 draft) – Fire Safety in Residential Buildings: Similar to BS 9999 but focused on residential (including high-rise flats). BS 9991:2024 includes provisions for evacuation lifts and their power supplies in taller residential buildings. Buildings over a certain height are now expected to have evacuation lifts with protected power supplies. BS 9991 also emphasizes secondary supplies for firefighting systems in apartment buildings (often referring to the same technical solutions as BS 9999). The latest fire safety legislation in England (Fire Safety (England) Regs 2022) has made it a legal requirement for high-rise residential buildings to have monthly checks of firefighting lifts and their backup power, reflecting the importance of these systems being operational at all times (Regulation 7).
BS 7671 (IET Wiring Regulations), especially Section 560: The national electrical installation standard (18th Edition) contains rules for Safety Services (Section 560). It requires that circuits supplying safety services be independent of other circuits and that safety power sources be arranged so that a fault in the normal supply cannot affect the backup supply. For example, Regulation 560.6.5 prohibits using two feeders from the same source unless it’s certain they won’t fail together. BS 7671 also covers requirements for emergency lighting, fire alarm wiring, and the use of generator/UPS systems (e.g. ensuring no backfeed to the grid, proper changeover arrangements, etc.). Compliance with the Wiring Regulations ensures that the installation of the emergency supply and associated switching meets basic electrical safety and reliability standards in addition to fire-specific codes.
BS EN 60947-6-1 – Automatic Transfer Switching Equipment (ATSE): This is the product standard that any ATS units should comply with. It covers the performance (electrical and mechanical) of transfer switches, including requirements for endurance, short-circuit strength, and safety interlocking. BS 8519 and BS 9999 both call for ATS devices to conform to BS EN 60947-6-1. Using a certified ATS helps ensure the changeover will function under emergency conditions and that the device has been type-tested (for example, to perform a given number of automatic operations, withstand fault currents, etc.).
BS EN 50598 series – Ecodesign for Power Drive Systems: This set of standards relates to the energy efficiency of motor drives and converters. While not specific to fire and safety, it can be relevant when selecting large motors or drive units for pumps and fans that will run on the emergency supply. BS EN 50598 provides an efficiency classification framework for variable speed drives, motors, and their components. In the context of firefighting power supplies, designers might refer to these standards to choose high-efficiency motors and drives (for smoke extract fans or sprinkler pump sets) that reduce load on the generator and operate reliably. In short, BS EN 50598 helps ensure that any powered equipment tied into the backup system is not unnecessarily wasteful or prone to overheating, though life safety considerations (reliability under stress) will take priority over pure efficiency.
BS EN 61936-1:2010 – Power Installations Exceeding 1 kV AC: This standard (identical to IEC 61936-1) provides common rules for designing and building high-voltage electrical installations, such as on-site substations or high-voltage generator connections. If a high-rise building’s emergency power system includes a high-voltage generator or an HV supply intake that feeds a transformer for life safety systems, then BS EN 61936-1 would apply to those portions. It covers things like the required fire barriers in substations, switchgear specifications, and safety distances. For instance, it contains guidance on using fire walls for HV equipment and other measures to prevent fire spread from electrical equipment. In essence, while BS EN 61936-1 is more about general electrical safety for high-voltage gear, adhering to it in a large building ensures that any high-voltage backup supply (or dual feed arrangement) is installed to robust safety standards in line with the life safety goals.
In addition to the above, there are numerous other standards and codes that come into play: BS EN 12845 (for automatic sprinkler systems) mandates backup arrangements for sprinkler pumps (either a secondary pump with independent drive or an emergency power supply for the pump); EN 12101-3 (for smoke and heat exhaust ventilators) requires fire-rated power supplies for smoke extract fans; EN 81-72 (for firefighting lifts) and upcoming EN 81-76 (for evacuation lifts) detail the expectations for lift operation under emergency power. All these specific standards essentially feed into the design, ensuring that the emergency power system as a whole meets the performance needed: e.g., a sprinkler pump must start on generator within a few seconds to keep water flowing, a lift must be able to run at full load on secondary power, etc. Compliance is typically demonstrated through a combination of component certifications (for cables, switches, etc.), following design principles from BS 8519/BS 9999, and ultimately testing the installed system.
Design Best Practices, Testing, and Maintenance
Designing an effective firefighting power supply system requires not only compliance with codes but also adherence to best practices learned from real-world performance. Some design best practices include:
Provide Adequate Fuel and Endurance: Ensure the standby generator has enough fuel on-site for the expected duration of an emergency. BS 8519 recommends a minimum of 4 hours of fuel for life safety generators used only during fires, and 8 hours if the generator also covers general standby duties. In critical facilities (like hospitals or mission-critical data centers), much larger fuel storage (24–96 hours worth) is often provided. Fuel storage should be in a properly vented, fire-safe location, and consider redundancy (multiple fuel tanks or a plan for refueling during a long incident).
Fire Protection of Equipment: House the emergency generator and associated switchgear in a 2-hour fire-rated enclosure or room. If the generator is external (e.g. in a weatherproof enclosure or container on ground or roof), ensure the enclosure has a fire resistance rating or is sited away from combustible structures. Fire dampers or seals should protect any openings (like ventilation intakes) to that room to prevent smoke ingress. Additionally, ensure ventilation and cooling for the generator such that it can run for hours without overheating.
Avoid Single Points of Failure: Where possible, use duplicated or parallel equipment for critical components. For example, some high-rise designs employ dual generators (one duty, one standby) so that if one fails, the other can take over. At the very least, a manual bypass for the ATS (as mentioned earlier) is provided. Critical control circuits might be duplicated and routed separately. Any scenario where one component failure could disable all backup power should be scrutinized – this includes fuel transfer pumps (having a backup pump), generator starters (many life safety generators have two starters and batteries), and control circuitry.
Selective Load Shedding: In the design, consider implementing load shedding or sequencing so that the generator is not overloaded. Life safety generators are sized for the full fire condition load, but starting all equipment at once can be challenging. Often, non-essential loads are not connected to the life safety generator at all, or are shed automatically. For example, elevators that are not designated for fire-fighting or evacuation might be programmed to park upon power failure and not run on generator to save capacity. Large smoke fans and pumps may be staggered on start-up via control logic. This ensures the generator can focus on truly critical services and handle the initial surge currents safely.
System Independence: Ensure that the normal and emergency power systems remain electrically isolated except at the approved changeover points. This may involve physically separating cable containment for normal vs. emergency circuits, using separate distribution boards (an “essential” board fed by the generator vs a “non-essential” board on mains), and careful earthing arrangements. As per the Wiring Regulations, if two independent supplies are used (e.g. a generator and the mains), backfeed must be prevented and paralleling should not occur unless specifically designed. Typically, the generator output is locked out from the mains by the ATS to avoid any unintended parallel operation or feedback into the grid.
Documentation and Signage: Clearly label all parts of the system. Cables for the secondary supply should be identified along their route. Switchboards should have notices indicating the presence of dual power sources and the location of the alternate supply isolator. In an emergency, this signage helps responders and engineers understand the system. Keep comprehensive schematics of the emergency power supply system accessible on site (and updated to reflect changes).
Once the system is installed, regular testing and maintenance are paramount. An emergency power system that is not maintained might fail just when it’s needed most. Key maintenance practices include:
Routine Generator Testing: It is recommended to test standby generators under load periodically. Many facility managers perform weekly no-load test runs (exercising the engine for a short period) and monthly load tests (often by simulating a power failure or using a test load bank). Regular testing ensures the generator engine is operational, lubricated, and that starting batteries are charged. In fact, regulations for hospitals require that the emergency generators start and assume load within a short timeframe (often 10–15 seconds) – regular tests validate this capability. During tests, key parameters like oil pressure, coolant temperature, and generator voltage/frequency should be monitored. Any issues (failure to start, slow transfer, etc.) can then be fixed before an actual emergency.
Automatic Transfer Switch Inspection: ATS units should be inspected and tested on a schedule (e.g. monthly or quarterly). A typical test involves simulating a mains failure to verify the ATS switches over to generator and back correctly. The transfer time and functionality of any bypass/isolation features should be checked. Given BS 8519’s recommendation for ATS maintenance without loss of supply, facilities with a bypass arrangement may periodically use the bypass to service the primary ATS. All moving parts in the switch and the controller logic should be in good working order. Firmware or control settings (if the ATS is programmable) should also be checked against any changes in building load configuration.
Fuel Management: Diesel fuel can degrade over time (formation of sludge, microbial growth, etc.), especially in standby tanks. Best practice is to implement a fuel maintenance program – this can include fuel polishing (filtration) systems, periodic fuel testing, and ensuring tanks are kept topped up. After any generator run, the fuel levels should be checked and refilled as needed. Tanks and fuel lines should be inspected for leaks or water ingress. In high-rise buildings, fuel is often pumped from a bulk storage tank at ground level to a day-tank near the generator; the pumps and controls for this fuel transfer system must also be tested.
Battery Maintenance: Backup batteries – whether for the generator start system, UPS units, or central battery emergency lighting – require routine maintenance. This includes checking electrolyte levels (for vented batteries), tightening connections, testing battery charge state, and capacity testing as applicable. For fire alarm panels, maintenance involves testing that the panel’s backup batteries can sustain the alarm for the required period. For generators, the starter batteries should be load-tested and replaced per manufacturer’s schedule to ensure the engine will crank when needed.
Preventive Maintenance and Inspection: All components of the emergency power system benefit from scheduled preventive maintenance. Generators typically have service intervals (e.g. annual or based on run hours) where oil and filters are changed, belts and hoses are inspected, and the engine is tuned. Switchgear should be inspected for signs of overheating, cleaned of dust, and exercised. Fire-resistant cabling doesn’t require the same routine intervention, but visual inspection for physical damage and ensuring the firestops around penetrations are intact is important. It’s also critical to keep the areas around emergency equipment clear – no storage of combustibles in the generator room, for instance.
Testing Under Simulated Conditions: At least once a year (or more frequently for high-risk occupancy like hospitals), a full system test should be conducted. This might involve a planned mains outage to confirm that the entire chain – from detection of power loss, generator start, ATS transfer, to operation of all connected life safety loads – works as designed. Such tests can be done after hours to avoid disruption. They provide confidence that during an actual power cut or fire, the systems will perform. Any failures or weaknesses observed can then be corrected. BS 9999 recommends that all life safety equipment, including backup power arrangements, be commissioned and tested under realistic conditions and thereafter inspected at least annually by competent persons.
Record Keeping: Maintain detailed logs of all tests, inspections, and maintenance activities. This includes logging generator test runs (date, duration, any issues), ATS tests, fuel checks, etc. In the UK, the responsible person for the building should also keep records to comply with the Fire Safety Order. For high-rise residential buildings, monthly checks of firefighting lifts and their backup power must be recorded and any defects reported to the local fire service if not rectified within 24 hours (per the Fire Safety (England) Regulations 2022). Good record keeping helps in auditing the reliability of the system and is invaluable for troubleshooting recurring issues.
By following these design and maintenance best practices, building owners and facilities managers can ensure that the firefighting backup power supply remains fully functional and dependable throughout the building’s life. The combination of robust initial design, compliance with strict standards, and ongoing care/verification means that in the critical moments of an emergency, the life safety power systems will perform their vital role in protecting lives.