In brief: Specify emergency lighting battery duration from the project jurisdiction, occupancy, evacuation plan and re-entry needs—not from battery amp-hours or a supplier default. The RFQ should state rated duration, emergency output, applicable rules, recharge expectations and the evidence required for approval.
The direct answer
Emergency lighting battery duration should be specified from the rules and risk conditions of the installation—not selected from a supplier's default battery pack. A usable specification states how long the luminaire must provide emergency operation, the emergency light output or design performance that must be sustained, the applicable project standard, the expected recharge condition, and the evidence required at sample approval and inspection.
The familiar values of 90 minutes, one hour and three hours come from different codes, standards and building-use decisions. They are not interchangeable global defaults.
What does rated emergency duration mean?
Rated duration is the period for which emergency lighting equipment is designed to operate in emergency mode under stated conditions. It is separate from the operating mode: maintained and non-maintained describe when the luminaire is illuminated, while duration describes how long emergency operation is available after the normal supply fails. For that distinction, see our maintained vs non-maintained emergency lighting guide.
Duration alone does not prove that an escape route will be adequately illuminated. The luminaire's emergency output, light distribution, mounting position, spacing and the complete emergency-lighting design still matter. In the United States, for example, OSHA requires exit routes to be adequately lighted, but that requirement does not turn one product runtime into a complete project design.
Why do buyers see 90-minute, 1-hour and 3-hour products?
These values reflect different regional frameworks and use cases. The comparison below is a procurement map, not a substitute for the authority having jurisdiction, a fire-risk assessment or a qualified emergency-lighting designer.
| Duration seen in specifications | What the source supports | Buyer action | |
|---|---|---|---|
| 90 minutes | UL guide information states that emergency power equipment with batteries provides 90 minutes of rated operating power, or more when marked | For a North American project, confirm the adopted code, UL 924 certification scope and model marking | |
| 1 to 3 hours | UK government fire-safety guidance says systems or individual luminaires are designed for durations between one and three hours | Ask the project designer which duration and occupancy assumptions apply | |
| 3 hours | The same UK guidance says three-hour designs are widely used and can support limited continued use during a power failure | Do not specify three hours only because it is common; record the project reason |
UL Solutions identifies UL 924 as the North American equipment standard for emergency lighting and power equipment. Its published guide information for emergency power and lighting equipment describes the 90-minute battery rating noted above. For UK projects, the government guide for offices and shops provides the one-to-three-hour context. A requirement from one market should not be copied into another market without checking the adopted rules.
Five decisions that set the right battery backup time
1. Which jurisdiction and project documents control?
Start with the project country, adopted building and fire rules, client specification, fire strategy and any instructions from the authority having jurisdiction. Name the required standard edition where the project team has confirmed it. Avoid a vague RFQ such as "CE emergency light, three hours": a conformity mark, a regional design requirement and a duration rating are different fields.
IEC 60598-2-22:2021 specifies particular requirements for emergency luminaires on emergency power supplies not exceeding 1,000 V and includes updated requirements for lithium batteries. It is a product-standard reference; the project team must still determine the installation duration and lighting design required in its jurisdiction.
2. Will occupants leave immediately?
Evacuation strategy and building use affect duration. A simple workplace that is evacuated and kept empty after a power failure presents a different decision from sleeping accommodation, healthcare, entertainment premises or a site that may remain partly occupied.
This is a regional example, not a universal rule: UK government guidance says three-hour designs are popular, while one-to-three-hour luminaires are available. The correct duration still follows the premises and its fire-safety strategy.
3. Can the premises be reoccupied before the batteries recover?
A duration test or real outage discharges the emergency battery. If occupants may return before recharge is complete, the system may not have its full emergency reserve for a second failure.
The UK government's sleeping-accommodation fire-safety guide says batteries typically take 24 hours to recharge and advises against reoccupation until the emergency-lighting system is fully functioning unless alternative arrangements are made. That statement is UK guidance and a typical value, not a promise for every battery. Put the model-specific recharge time and re-entry plan in the project review.
4. What emergency output must last for that period?
Do not specify duration without output. Ask for the emergency lumen output or the project photometric performance, including the applicable measurement or test evidence. Normal-mode wattage, normal-mode lumens and battery amp-hours do not establish emergency illumination by themselves.
For a buyer, the practical rule is simple: compare models at the required duration and emergency output under the same stated conditions. If one supplier quotes "three hours" without emergency output and another supplies duration plus photometric evidence, the two quotations are not technically equivalent.
5. What environmental and lifecycle conditions apply?
Battery chemistry, ambient temperature range, charger design, storage time, installation environment and battery ageing can affect available performance. Do not calculate compliance from nominal amp-hours alone. Ask the manufacturer for the exact model's rated duration, operating temperature, battery specification, recharge information, test method and replacement instructions.
Battery capacity is not the duration specification
Battery voltage and amp-hour capacity describe part of the energy source. Emergency runtime also depends on the load, emergency driver, control circuit, conversion losses, discharge limits and operating conditions. Two luminaires with the same nominal amp-hour rating can therefore have different emergency output and duration.
Editorial recommendation: use battery data to check configuration consistency, but approve the product against model-specific duration and output evidence. Do not ask a procurement team to infer life-safety performance from a battery label.
Evidence to request before approval
Build the approval file around the exact model and configuration:
- Product data sheet showing input, operating mode, rated duration, emergency output, battery chemistry and capacity
- Model marking and the certification or test scope required by the project
- Emergency-output photometric data or the design evidence requested by the lighting consultant
- Full-duration sample test method and acceptance criteria
- Recharge time, charge indicator behaviour and instructions after a full discharge
- Operating and storage temperature limits
- Battery replacement instructions and spare-part identification
- Wiring diagram, test switch or self-test behaviour, and installation instructions
- Approved sample record linking the tested configuration to the purchase specification
Government guidance for UK offices and shops asks whether luminaires operate for their full rated duration. That is a useful procurement control even outside the UK: the factory or inspection plan should test the duration actually ordered, not merely confirm that the lamps switch on.
An RFQ block buyers can copy
Use this as a starting point and have the project designer complete the bracketed fields:
- Project country / jurisdiction: [country, state or region]
- Applicable project standard and edition: [confirmed by project team]
- Building use and evacuation strategy: [description]
- Required rated emergency duration: [90 minutes / 1 hour / 3 hours / other]
- Required emergency output or photometric criterion: [lumens, distribution or design requirement]
- Operating mode: [maintained / non-maintained / switchable]
- Input voltage and frequency: [value]
- Battery chemistry or restriction: [value or no preference]
- Operating and storage temperature: [range]
- Maximum recharge time / re-entry condition: [value or operational rule]
- Test function: [manual / self-test / central monitoring]
- Required certification, report and marking: [model-specific list]
- Sample and pre-shipment duration test: [method, quantity and acceptance criterion]
Zhuiming configuration boundary
Hangzhou Dreamy Technology Co., Ltd. currently states a standard emergency-duration configuration of 180 minutes and evaluates other battery capacities and durations for OEM projects. The F355MN emergency conversion kit, for example, lists a one-to-three-hour customizable range in the current product catalog.
Those are company-reported configuration capabilities, not a claim that every Zhuiming model meets every market's rules. Final duration, emergency output, battery, marking and compliance scope are confirmed against the exact model, approved sample, order specification and requested evidence. Buyers can review the OEM and ODM process or send a project-specific RFQ.
Sources and scope
- IEC: IEC 60598-2-22:2021, particular requirements for emergency luminaires
- UK Government: Fire safety risk assessment for offices and shops
- UK Government: Fire safety risk assessment for sleeping accommodation
- UL Solutions: Emergency lighting testing and certification
- UL Solutions Code Authorities: Emergency lighting and power equipment guide information
- US OSHA: Exit-route lighting and marking requirements
Sources reviewed 29 July 2026. This article provides procurement guidance. It does not replace project-specific emergency-lighting design, a fire-risk assessment, adopted codes, certification review or approval by the responsible authority.
Frequently asked questions
How long should an emergency light battery last?
The required duration depends on the project's jurisdiction, building use, evacuation strategy and re-entry plan. Common specifications include 90 minutes, one hour and three hours, but none is a universal global default.
Is 90 minutes enough for emergency lighting?
Ninety minutes is common in North American emergency-lighting equipment and code pathways, but it is sufficient only when the adopted project requirements, design and model certification support it.
When is three-hour emergency lighting used?
UK government guidance describes one-to-three-hour systems and notes that three-hour designs are widely used. The project designer should still justify the duration from the premises, evacuation and reoccupation conditions.
Can battery amp-hours prove emergency light duration?
No. Battery capacity is only one input. The luminaire's load, driver, discharge limits, temperature and other conditions affect output and runtime, so buyers should request model-specific duration and emergency-output evidence.
What should an emergency lighting duration RFQ include?
State the jurisdiction, applicable project standard, occupancy and evacuation strategy, rated duration, emergency output, operating mode, voltage, temperature range, recharge condition, test method and model-specific evidence required for approval.