A maintained emergency light is lit whenever the normal lighting is on and stays lit on its battery if the mains supply fails. A non-maintained emergency light stays off during normal use and only switches on when the supply to the normal lighting fails. A third type, the sustained (or combined) luminaire, contains two or more lamps, and at least one of them is dedicated to emergency use. The right choice depends on how the building is used, and your fire risk assessment and emergency lighting design should decide it.
This guide explains each mode, where it is typically used, how selectable maintained/non-maintained luminaires work and what else you should check before you buy.
What is maintained emergency lighting?
In a maintained luminaire, the lamp works as part of the normal lighting and carries on working in an emergency. If the mains supply fails, an internal battery (or a central battery system) takes over and keeps the lamp lit for the luminaire's rated duration.
Self-contained maintained fittings usually have two live connections:
- A permanent (unswitched) live, which keeps the battery charged and lets the fitting detect a mains failure.
- A switched live, which lets the lamp be switched on and off with the normal lighting circuit.
Because the unswitched live keeps watching the supply, the emergency lamp still comes on when the power actually fails, even if the switched lighting has been turned off.
Where maintained emergency lights are typically used
Maintained operation is common in places of assembly and entertainment, such as theatres, cinemas, nightclubs, halls and similar venues. In these places the normal lighting is often dimmed or switched off while the building is occupied, and visitors may not know the building. An illuminated exit sign that is always lit helps people find the way out before anything goes wrong.
Manufacturer guidance on BS 5266-1 recommends that final exit signs are of the maintained type. It also notes that licensed premises, places of entertainment and buildings with sleeping accommodation may be subject to local requirements, so check with the relevant authority. You can browse our maintained emergency lighting range for fittings designed to run in this mode.
What is non-maintained emergency lighting?
A non-maintained emergency light is off during normal use while its battery charges from the permanent supply. When the supply to the normal lighting fails, the luminaire switches to battery power and lights up automatically.
Where non-maintained emergency lights are typically used
Non-maintained is the usual choice for workplaces and similar buildings where the normal artificial lighting is on whenever the premises are occupied. Typical locations include:
- offices, warehouses and factories
- corridors, stairwells and escape routes
- plant rooms, toilets and other areas that need emergency lighting under the design
The lamp is not lit day to day; these fittings only light up during testing or when the normal lighting supply fails. See our non-maintained emergency lighting collection.
What is sustained (combined) emergency lighting?
A sustained or combined luminaire contains two or more lamps. At least one lamp runs from the normal supply, and at least one is dedicated to emergency use and runs from the emergency supply when the mains fails. The terms are often used loosely, and product data sheets vary, so always check exactly how a fitting behaves before you specify it.
Maintained vs non-maintained at a glance
| Mode | Normal conditions | Mains failure | Typical uses |
|---|---|---|---|
| Maintained (M) | Lamp lit (can be switched with the normal lighting) | Lamp stays lit on battery | Places of assembly and entertainment, areas where lighting is dimmed, final exit signs |
| Non-maintained (NM) | Lamp off, battery charging | Lamp lights on battery | Offices, workplaces, corridors, stairwells |
| Sustained / combined | Normal lamp lit | Dedicated emergency lamp lights | Applications where one fitting provides both normal and emergency light |
Product listings often abbreviate the mode and duration, so "M3" means maintained, 3-hour and "NM3" means non-maintained, 3-hour.
Selectable (M/NM) luminaires
Some emergency bulkheads, exit signs and similar fittings are selectable, which means they can be set up as either maintained or non-maintained when they are installed. On many models this is done with the wiring. For example, a link between the permanent live and switched live terminals may be left in place for maintained operation and removed for non-maintained operation. Other models use a switch or a setting in the fitting.
The method varies between manufacturers, so always follow the installation instructions. Wiring and configuration should be carried out by a competent electrician. Selectable fittings are useful when one product needs to cover different areas of a site, or when the building's use may change.
Other things to check when choosing emergency lighting
Duration: 1 hour or 3 hours
The operating mode tells you when the lamp is lit. The rated duration tells you how long it stays lit on battery. Manufacturer guidance on BS 5266-1 says a 3-hour duration is appropriate where evacuation is not immediate or where early re-occupation may be needed. A 1-hour duration may be acceptable where evacuation is immediate and re-occupation is delayed until the system has recharged. Premises with sleeping accommodation, such as care homes, guest houses and boarding schools, are examples that call for 3 hours.
Self-test or manual test
Every emergency luminaire needs regular testing whatever its mode. It typically needs a short functional test every month and a full rated-duration test once a year, and all results should be recorded. Self-test fittings run these checks automatically and show the result. Standard fittings are usually tested manually using an emergency light test key fitted to a key switch on the lighting circuit. Our emergency lighting testing guide explains each test step by step.
Fitting type and location
Choose the housing to suit the space. Bulkheads suit corridors and plant rooms, recessed downlights suit ceilings, twin spots suit large open areas and illuminated signs suit exits. Check the IP rating for damp or outdoor locations. Spacing and light levels should come from the emergency lighting design, not from guesswork.
How to choose: a quick checklist
- Start with your fire risk assessment and emergency lighting design (BS 5266-1 is the UK code of practice; see our guide to emergency lighting regulations).
- Decide the mode for each area: maintained for exit signs and areas where lighting is dimmed or the public are present, non-maintained for general escape routes in workplaces.
- Confirm the duration (1 or 3 hours) required for the premises.
- Decide between self-test and manual test, and how testing will be recorded.
- Check the IP rating, mounting and any licensing or local authority requirements.
You can browse the full emergency lighting range, including bulkheads, downlights, twin spots and exit signs. All products are genuine, brand new and factory sealed, with fast, tracked UK delivery.
Frequently asked questions
What does a maintained emergency light mean?
It is an emergency luminaire whose lamp is lit during normal operation and stays lit on battery power when the mains supply fails. It can usually be switched with the normal lighting while its battery keeps charging from a permanent supply.
What does non-maintained emergency lighting mean?
It is an emergency luminaire that stays off during normal operation and only lights up, on battery power, when the supply to the normal lighting fails.
Do I need maintained or non-maintained emergency lighting?
It depends on how the premises are used. Maintained is typically used where normal lighting may be dimmed or where members of the public unfamiliar with the building are present, such as places of entertainment. It is also recommended for final exit signs. Non-maintained is typical for workplaces where the lights are on whenever the building is occupied. Your fire risk assessment, emergency lighting design and any licensing conditions should decide it.
Can a maintained emergency light be used as non-maintained?
A selectable (M/NM) luminaire can be set up either way at installation, usually by wiring or a setting described in the manufacturer's instructions. A fitting sold as maintained-only should be installed as the manufacturer intends. Ask a competent electrician if you are unsure.
How often should emergency lighting be tested?
Typically, every luminaire gets a short functional test each month and a full rated-duration test once a year, and the results are recorded. Self-test fittings can automate this, but someone still needs to check and log the results.
This guide is general information; follow your fire risk assessment and a competent person's advice.