Introduction.
Emergency lighting is a self-descriptive term and is lighting for an
emergency situation when the main power supply fails. The loss of mains
electricity could be the result of a fire or a power cut and the normal
lighting supplies fail. This may lead to sudden darkness and a possible
danger to the occupants, either through physical danger or panic.
Emergency lighting is normally required to operate fully automatically
and give illumination of a sufficiently high level to enable persons of
all ages to evacuate the premises safely. Most new buildings now have
emergency lighting installed during construction, the design and type
of equipment is normally specified by the relevant local authority, architect
or consultant.
The British Standard provides the emergency lighting designer with laid
down guide lines which form the general basis for him to work on. British
Standard BS 5266: Part 1: 2005 includes in its scope residential hotels,
clubs, hospitals, nursing homes, schools and colleges, licensed premises,
offices, museums, shops, multi-storey dwellings etc. Although this standard
recommends the types and durations of emergency lighting systems relating
to each category of premise it should be remembered that the standards
are minimum safe standards for the types of premises and that a higher
standard may be needed for a particular installation.
Type of system
Most emergency lighting schemes fall into one of the following categories:-
- Non-maintained - The emergency light units only illuminate in the
event of a mains failure.
- Maintained - The emergency light units are illuminated at all times
using the same lamps for both normal and emergency operation.
- Sustained - The emergency light units are fitted with two lamps or
two sets of lamps. One of which operates on mains 240V AC supply, the
other which operates from the battery supply in the event of mains failure.
It is basically a non-maintained system with the addition of mains lamps
which should be illuminated whenever the premises are occupied.
The type of system and emergency duration is often expressed in abbreviated
form as per the following examples:-
- M3 - Maintained System, emergency duration 3 hours.
- NM2 - Non-maintained System, emergency duration 2 hours.
- S1 - Sustained System, emergency duration 1 hour.
Emergency Luminaires
An emergency luminaire will either be of the self-contained type, i.e.
with all components integral to the luminaire body (battery, charging
circuit, mains ballast etc). Or "slave" to a central battery
system where only the lamp (and an inverter if fluorescent) is located
within the luminaire body and the supply on power failure is fed from
some centralised point.
The majority of systems installed in the United Kingdom are of the self-contained
type, but both options have their own advantages and disadvantages.
Emergency Power Supplies
Central Battery Source
Advantages
- Maintenance and routine testing is easier with only one location
to consider;
- Superior battery life, between 5 and 25 years dependant upon type;
- Environmentally stable in a protected environment, luminaires able
to operate at relatively high or low ambient temperatures;
- Large batteries are cheaper per unit of power and luminaires are
usually less expensive.
Disadvantages:
- High capital equipment costs;
- High installation and wiring costs with essential MICC or Pirelli
FP200 type cable to each slave luminaire;
- Poor system integrity - failure of battery or wiring circuit can disable
a large part of the system;
- Requirement for 'battery room' to house cells and charger circuits
etc, may also require ventilation of acid gases;
- Localised mains failure may not trigger operation of emergency lighting
in that area.
- Voltage drop on luminaires wired furthest from the central battery
could become a problem.
Self Contained - Single Point
Advantages:
- Speedy and low cost installation;
- Standard wiring material may be used (failure of mains supply due
to cable burning through will automatically satisfy the requirement
for a luminaire to be lit);
- Low maintenance costs - periodic test and general cleaning only required;
- Low hardware equipment costs – no requirement for extended
wiring,special ventilation etc.
- Greater system integrity with each luminaire independent of the other;
- System can easily be extended with additional luminaire's;
- No special sub-circuit monitoring requirements.
Disadvantages:
- Limited environmental operating range (batteries may be adversely
affected by a relatively high ambient temperature);
- Battery life is limited to between 2 and 4 years dependant upon application;
- Testing requires isolation and observation of luminaire's on an individual
basis.
In general then,the decision to use either a central battery or a self-contained
system is likely to be cost dominated. If an installation has longevity
and low maintenance as priorities, then the higher cost of central battery
may be acceptable on a very large project. Usually, luminaire and installation
costs will be a major consideration, particularly on smaller jobs, and
it is this criterion which makes the self-contained luminaire the most
popular choice.
How much light?
BS5266 recommends the provision of a horizontal illumination at floor
level on the centre line of a defined escape route (permanently unobstructed)
not less than 0.2 lux and 0.5 lux minimum for anti panic areas to exclude
0.5 metre border around the room. In addition, for escape routes of up
to 2m wide, 50% of the route width should be lit to a minimum of 0.1 lux.
Wider escape routes can be treated as a number of 2m wide bands. The actual
degree of illumination should be closely related to the nature of both
the premises and its occupants with special consideration being given
to old person’s homes, hospitals, crowded areas such as pubs, discos
and supermarkets, and to whether or not the premises are residential.

Typical emergency lighting units
Siting of luminaire's/signs
Having decided on your basic system, consideration should now be given
to the siting of the lighting units and signs within the particular premises
involved. This will then form the basis on which your selection of equipment
can be made.
Lighting units and signs should be sited so as to clearly show the exit
routes leading to the final exits from the premises. Where the exit route
or final exit is not readily identifiable a sign should be utilized rather
than a lighting unit. Particular attention should be paid to individual
stairways, changes in level, corridor intersections, changes in direction,
the outside of each final exit, control/plant rooms, lifts, toilet areas
over 8m2 (although in some peoples opinion all toilets of public access
and especially those for the disabled should have emergency lighting).
Access to fire alarm call points, fire fighting equipment, should be clearly
illuminated.
In general, if common sense is used when siting the luminaires and signs
to cover these areas, then the completed scheme will meet most requirements.
Note. Detailed computer point calculations or luminaire manufacturers
spacing tables should be used.
Areas to be covered
There is legislation, guides, British and European standards that require
emergency lighting to be installed and the ares it should cover. An emergency
escape lighting system should normally cover the following ares,
- each exit door;
- escape routes;
- intersections of corridors;
- outside each final exit and on external escape routes;
- emergency escape signs;
- stairways so that each flight receives adequate light;
- changes in floor level;
- windowless rooms and toilet accommodation exceeding 8m2;
- firefighting equipment;
- fire alarm call points;
- equipment that would need to be shut down in an emergency;
- lifts and areas in premises greater than 60m2.
It is not necessary to provide individual lights (luminaires) for each
item above, but there should be a sufficient overall level of light to
allow them to be visible and usable.
Testing
BS EN 50172:2004/ BS 5266-8:2004 Emergency escape lighting systems. Specifies
the minimum provision and testing of emergency lighting for different
premises
The system should include adequate facilities for testing the system
condition. These need to be appropriate for the specific site and should
be considered as part of the system design. Discussions with the user
or system designer should identify:
- The caliber and reliability of staff available to do the testing
- The level of difficulty in performing the test
- Discharge tests need to be done outside normal working hours. In
buildings that are permanently occupied the test should be phased so
only alternate luminaires are tested.
The testing requirements are:
Function test
- All emergency luminaires should be tested be breaking the supply
to them and checking that they operate satisfactorily.
- The supply must then be restored and the charging indicators must
be seen to be operating correctly.
- This test must be performed at least once per month.
Discharge test
- The luminaires must be tested for their full rated duration period
and checked for satisfactory operation. The supply must then be restored
and the charging indicators rechecked. This test must be performed at
least annually.
Manual Testing
If manual testing is utilised, the following points should be considered:
- Is a single switch to be used? Unless the whole building is to be
switched off, a separate switch should be used for each circuit. As
the feed to non-maintained circuits must be taken from the switch this
will probably mean that the building will have to be walked around twice,
once to check the luminaires and once to check that they are recharging
- Are luminaires to be individually switched? In practice, only a single
walk around the building will be needed. However, the test switches
could spoil the decor of the building and they must be of a type that
is tamper proof.
After the tests it is recommended that the performance of the luminaires
should be logged.
Automatic Testing
If the costs of an engineer time and the disruption caused by manual
testing are excessive, automatic systems should be considered. Different
formats are available to match particular site requirements.
Commissioning Certificate
BS5266 and the European Standard both require written declarations of
compliance to be available on site for inspection. These consist of
- Installation quality.
IEE regulations must have been conformed with and non-maintained fittings
fed from the main circuit of the normal lighting system, as required
in BS 5266
- Photometric performance.
Evidence of compliance with light levels has to be supplied by the system
designer.
- Declaration of a satisfactory test of operation.
A log of all system tests and results must be maintained. System log
books, with commissioning forms, testing forms and instructions should
be provided by the installer.
On completion of the installation of the emergency lighting system, or
part thereof, a completion
certificate should be supplied by the installer to the occupier/owner
of the premises. The Building Control Department should insist upon a
copy of this certificate which will be retained with the Building Regulations
Authority.
Maintenance
Finally, to ensure that the system remains at full operational status,
essential servicing should be defined. This normally would be performed
as part of the testing routine, but in the case of consumable items such
as replacement lamps, spares should be provided for immediate use.
Summary of guidance covering emergency lighting.
British Standard 5266 - Emergency Lighting
Emergency lighting is now covered by a series of interdependent standards
which can be seen as forming a hierarchy as shown below.
Base guidance document
BS 5266-1 Emergency lighting-Part 1: Code of practice for emergency lighting
of premises
Gives general rules and guidance on the provision and operation of emergency
lighting in most premises other than dwellings
System standards
BS EN 1838:1999/ BS 5266-7:1999 Lighting applications - Emergency lighting
Specifies the illumination to be provided by emergency lighting (including
luminance, duration and colour)
BS EN 50172:2004/ BS 5266-8:2004 Emergency escape lighting systems
Specifies the minimum provision and testing of emergency lighting for
different premises
Product standards
BS EN 60598-2-22:1999 Luminaires for emergency lighting. Specifies self
contained and centrally powered luminaires for use in emergency lighting
systems.
IEC 62034-1 Automatic test system for battery powered emergency escape
lighting. Specifies a test system for battery powered emergency lighting
BS EN 50171:2001 Central power supply systems. Specifies central power
supply systems for luminaires for emergency lighting
Check out your local reference library or purchase copies. Check out BSI
Online and insert the BS number to see what standards are
available and their titles.
Regulatory Reform (Fire Safety) Order
The guides for the above order has a "Section 5 Further guidance
on emergency escape lighting" which will provide you with relevant
information. Check out Fire
safety law and guidance documents for business
Approved Document "B"
Check out Approved
Document "B"
This handout provides a general overview
and basic information on this topic. It may not apply to everyone, consequently
to find out if this guide applies to you and to get more information
on this subject, study all the relevant legislation, guides and British/European
Standards. Also you should seek advice from an expert on the subject
or your local Fire Safety Officer or Fire Safety Professional.

The Fire Safety Advice Centre. Permission is granted to print and photocopy
this material for nonprofit educational uses.
[Index]
[Advice Centre]
This page was last checked and
modified on
Saturday, 8 November, 2008 18:13
|