Rated duration is the minimum time an emergency lighting installation must stay on after the normal supply fails. Under EN 1838 it is at least 1 hour for escape routes; many countries require longer for certain buildings – in Germany, for example, 3 hours is common for places of assembly, retail premises and other high-risk buildings, and 8 hours in some cases. What counts for your building is the building permit, national building regulations and the fire safety strategy – and the installation must still achieve that duration years later.
What is rated duration?
Rated duration is the time, declared by the manufacturer and specified by the designer, for which an emergency luminaire or installation delivers the required illuminance in emergency mode. It is marked on the luminaire's rating label, for example as "1 h" or "3 h", as part of the marking required by EN 60598-2-22.
The key distinction is between what a luminaire can do when new and what it must deliver over its whole service life. Rated duration is not a snapshot: it has to be demonstrated again at every annual test. Which illuminance levels apply during that time is covered in emergency lighting illuminance.
Which durations are common?
| Rated duration | Typical application | Basis |
|---|---|---|
| 1 hour | Minimum for escape routes; common in workplaces such as offices where no longer duration is required | EN 1838, risk assessment |
| 3 hours | Common in places of assembly, retail premises, hotels, high-rise buildings and other high-risk buildings (e.g. Germany; also widely used in the UK) | National building regulations, in Germany DIN VDE V 0108-100-1 and special building regulations |
| 8 hours | Certain buildings in some countries, e.g. in Germany for accommodation or care homes depending on rules and operating mode | National rules, fire safety strategy |
| Other values | High-risk task areas: as long as the hazard exists or until the activity can be safely ended | EN 1838, risk assessment |
The table shows typical assignments, not a binding list. The required duration can differ depending on country, region, use and fire safety strategy.
Why 3 hours?
In many buildings one hour is enough to get everyone outside safely. In buildings with many people, people unfamiliar with the premises or people who need assistance, emergency lighting should also support fire service rescue and firefighting and bridge a longer outage. That is why building regulations in several European countries, including Germany, commonly require 3 hours for such buildings.
When are 8 hours required?
Longer durations such as 8 hours are specified in some national rules for buildings where people are present at night and cannot be evacuated immediately during a prolonged power cut, such as accommodation or care homes in Germany. Whether 8 hours apply there also depends on the operating mode: in maintained mode the emergency luminaires are on permanently, in non-maintained mode they only switch on when the mains fails. The specific requirement follows from the building permit and the fire safety strategy.
Practical tip: Get written confirmation of the required rated duration before design starts – from the building permit, fire safety strategy or risk assessment. Choosing luminaires with a 3-hour duration from the outset leaves reserves in case the use changes later.
What applies to workplaces?
Across the EU, the Workplace Directive 89/654/EEC requires emergency lighting of adequate intensity where workers would be exposed to risk if the lighting failed; the details are set nationally. In Germany, for example, the requirement follows from the Workplaces Ordinance (ArbStättV), specified in more detail by the technical rules ASR A2.3 (escape routes and emergency exits) and ASR A3.4/3 (emergency lighting and safety guidance systems), on the basis of the employer's risk assessment.
The principle is the same everywhere: emergency lighting must work for at least as long as people need to leave the workplace safely – and, in high-risk task areas, until the dangerous activity has been safely ended. Many workplaces without special building requirements are designed for the 1-hour minimum of EN 1838. If the building is also subject to stricter rules, for example as a retail premises, the longer requirement generally applies. When emergency lighting is required at all is explained in emergency lighting requirements.
How is the duration tested?
EN 50172 calls for an annual duration test. The normal supply is interrupted or simulated, and every luminaire must stay lit for its full rated duration. If a luminaire switches off early or becomes significantly dimmer, the test is failed.
- Monthly: function test – switch to emergency mode, all luminaires and signs must light up. It does not check duration.
- Annually: duration test over the full rated duration.
- Records: date, result, defects found and how they were rectified, entered in the logbook.
Self-testing luminaires to EN 62034 carry out the duration test automatically and log the result. For details on intervals see emergency lighting testing intervals, and on automatic tests self-testing emergency lights.
How long does recharging take?
After a duration test or a real power cut the battery is discharged. Until it is fully recharged, the full duration is not available. Under EN 60598-2-22, self-contained luminaires must be designed to reach their rated duration again after a 24-hour recharge.
This has two practical consequences:
- Schedule tests outside occupied hours: ideally leaving enough recharge time before the building is used again, for example before a weekend or overnight.
- Do not test all luminaires at once: in buildings that are used around the clock, it can make sense to test adjacent luminaires alternately so that no area is ever left without charged luminaires. Self-testing systems can stagger tests accordingly.
Why do ageing batteries put the duration at risk?
Every battery loses capacity over the years, even with little use. High ambient temperatures speed this up. A luminaire that comfortably exceeds three hours when new can fall below the required duration after a few years – while the monthly function test is still passed.
That is exactly why the annual duration test is indispensable. Failing it usually means the battery must be replaced. How the different chemistries age and when to replace them is covered in emergency light batteries. NOTLUX Series 19 uses LiFePO4 batteries with up to 3 hours of emergency operation depending on the model, – with the maintenance contract, NOTLUX replaces all batteries in year 5 to 6.
Frequently asked questions
What is the minimum duration for emergency lighting?
Under EN 1838, at least 1 hour for escape routes. Many countries require longer for certain buildings; in Germany, for example, 3 hours is common for places of assembly and retail premises. The building permit, national regulations and the fire safety strategy are decisive.
What does "3 h" on an emergency light's label mean?
It is the rated duration: the luminaire is designed to stay lit in emergency mode for at least 3 hours after a mains failure. It must still achieve this at the annual test years later.
Can I install a 3-hour luminaire where only 1 hour is required?
Yes, a longer rated duration than required is generally acceptable and provides reserves, for example for a later change of use. The reverse is not: a luminaire with a shorter duration must not be used where a longer one is required.
How long does an emergency light take to recharge after a power cut?
Self-contained luminaires are designed to reach their full rated duration again after 24 hours of charging. During the recharge period only part of the duration is available.
What happens if a luminaire fails the duration test?
The defect is recorded in the logbook and must be rectified promptly, usually by replacing the battery. A repeat test is then advisable. Depending on where the luminaire is, interim measures may be needed until the fault is fixed.
Emergency lighting without worries.
Luminaires, installation and maintenance from a single source – every inspection documented digitally in our app. We start with a free on-site survey and standard-compliant design.