In maintained mode an emergency luminaire is lit whenever the building is in use and stays lit without interruption if the mains fails; in non-maintained mode it is off during normal operation and only lights when the normal supply fails. Exit signs are operated in maintained mode in many workplaces and places of assembly, while luminaires lighting escape routes are usually non-maintained. Which mode is required generally follows from national building rules, the building permit and the fire safety strategy.
What do maintained and non-maintained mean?
The operating mode describes when an emergency luminaire is lit: only in an emergency, or also during normal operation. It is independent of whether the luminaire has its own battery or is supplied from a central battery.
| Mode | Definition | Typical application |
|---|---|---|
| Maintained | The lamp is lit whenever the building is in use and stays lit when the supply fails | Exit signs in many workplaces and places of assembly |
| Non-maintained | The lamp is off in normal operation and lights only when the supply to normal lighting fails | Luminaires lighting escape routes and open areas |
| Switched maintained | The lamp is switched together with the normal lighting and changes to emergency operation automatically on supply failure | Rooms where the sign should only be lit during use |
In German the modes are called Dauerschaltung (maintained) and Bereitschaftsschaltung (non-maintained). An overview of all categories of emergency lighting is given in Types of emergency lighting.
How does maintained mode work?
In maintained mode the lamp is supplied from the mains during normal operation. If the mains fails, the luminaire's battery or the central battery takes over without the luminaire visibly going out. For exit signs this has a clear advantage: the sign is always visible, people learn the escape direction and exit in everyday use, and a failed lamp is noticed on every walk-round.
How does non-maintained mode work?
In non-maintained mode the luminaire stays dark while the normal supply is healthy; the charging circuit simply keeps the battery full. Only when the mains fails does it switch on and light the escape route. This is the usual solution for safety luminaires without a pictogram, because the normal lighting provides light during everyday operation. A failed lamp, however, cannot be seen in daily use – it only shows up in the function test or self-test.
What is switched maintained?
With switched maintained operation, the emergency luminaire is only lit when the room's normal lighting is switched on, for example via the light switch or a control system. On mains failure it goes into emergency mode regardless. This is an option where a room is not permanently in use and the sign should only be lit during use. Whether it is permitted depends on the type of building and the requirements set for it. The luminaire must remain permanently connected to an unswitched supply for charging and mains monitoring; otherwise it would treat switching off the light as a power failure.
Where must exit signs be maintained?
There is no single rule for all buildings. EN 50172 and EN 1838 form the European basis, but when maintained exit signs are required is largely decided nationally. As a rule, maintained mode is required where many people, often unfamiliar with the building, are present, or where rooms may be darkened during use. Example Germany:
- Places of assembly: the model ordinance for places of assembly (MVStättVO) and the corresponding state ordinances generally require exit signs to be lit continuously while the venue is in operation.
- Retail premises: exit signs are often maintained so that customers can see the way out at any time.
- Hotels, hospitals and care homes: people are present at night; maintained exit signs are frequently required.
- Rooms darkened during use: such as cinemas, stages or event spaces, where signs would not be visible without their own lighting.
In Germany, the decisive documents for a building are the state building code and special building regulations, the building permit and the fire safety strategy. The former pre-standard DIN VDE V 0108-100-1, replaced by DIN EN 50172 (VDE 0108-100):2024-10, is still often used as orientation. Other countries have their own rules – the UK, for example, sets out recommendations in BS 5266-1. Which buildings need emergency lighting at all is covered in Emergency lighting requirements.
Practical tip: Record the operating mode of every luminaire in the luminaire list of the logbook. If an exit sign is accidentally connected to a switched circuit, it will often report a mains failure when the lights are switched off – and drain its battery.
How much energy does maintained mode use?
Since exit signs moved to LED, the energy demand of maintained operation has become small. An example for an LED exit sign drawing 2 W in continuous operation:
- 2 W × 8,760 hours per year = about 17.5 kWh per year per luminaire.
- For 30 luminaires, that is about 525 kWh per year.
Older exit signs with fluorescent lamps and conventional control gear drew several times that power, and the lamps had to be replaced regularly. The exact power consumption is stated in the datasheet. If you are considering converting an older installation, see Upgrading emergency lighting.
How does the operating mode affect the battery?
In self-contained luminaires, the lamp in maintained mode is supplied from the mains during normal operation, not from the battery. The battery is therefore not discharged more than in non-maintained mode. A difference can arise through temperature, however: a permanently lit lamp produces heat inside the housing, and higher temperatures accelerate battery ageing. How much this matters depends on the luminaire design, power and installation. Modern low-power LED luminaires with temperature-stable batteries such as LiFePO4 are much less critical here than older designs. More on battery types in Emergency light battery.
The required rated duration can also be linked to the operating mode: for buildings occupied at night, some national rules mention longer durations such as 8 hours depending on the mode. Details in Emergency lighting duration.
How can you tell a luminaire's operating mode?
The operating mode a luminaire is designed for is stated on the rating plate and in the datasheet. The product standard EN 60598-2-22 provides for marking with a short code. Among other things, it contains a letter for the supply type (X for self-contained, Z for centrally supplied), a digit for the mode (0 for non-maintained, 1 for maintained) and the rated duration in minutes. Further characters can indicate additional features such as a test device. The full legend is in the manufacturer's datasheet.
Many luminaires can be set to maintained or non-maintained mode during installation, for example through the way they are wired or by a switch. How a luminaire actually operates is therefore decided by the connection on site – and should be recorded in the handover documentation.
Frequently asked questions
What is the difference between maintained and non-maintained emergency lighting?
Maintained luminaires are lit whenever the building is in use and stay lit when the mains fails. Non-maintained luminaires are off in normal operation and only light on mains failure. Which mode is required depends on the use of the building, national rules and the fire safety strategy.
Do exit signs always have to be lit?
Not in every building, but in many. In places of assembly, retail premises and buildings occupied at night, maintained exit signs are generally required. The decisive documents are the building permit, national building regulations and the fire safety strategy.
Can I switch off an exit sign at night?
Where maintained mode is required, not while the building is in use. Some systems offer a rest or inhibit function outside operating hours, which must be designed so that safety lighting is available when needed. Check whether this is permitted with your lighting designer or qualified electrician.
Does maintained mode use a lot of electricity?
With LED, hardly. A 2 W LED exit sign uses about 17.5 kWh per year in continuous operation. Older fluorescent luminaires needed several times as much.
Does the battery age faster in maintained mode?
The battery is not discharged further in maintained mode, because the lamp is supplied from the mains during normal operation. The heat from a permanently lit lamp can accelerate ageing, though. With modern low-power LED luminaires the effect is usually small.
What is switched maintained emergency lighting?
A switched maintained luminaire is lit together with the room's normal lighting and changes to emergency operation automatically on mains failure. Charging continues via an unswitched supply. Whether this option is permitted depends on the requirements for the building.
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