Emergency Lighting
Robin Wright
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A
1930s fitting converted for use as a mains/emergency fitting |
Emergency lighting
almost invariably consists of ugly boxes fixed to ceilings and bulkheads.
These fittings disfigure the corridors and spaces which form the escape
routes in interesting modern and historic interiors alike. Yet there are
perfectly effective alternatives which will satisfy fire safety requirements,
including discreet modern fittings such as fibre optics. In historic buildings
any early light fittings which survive can also often be adapted to provide
a sympathetic solution.
IS PERMANENT EMERGENCY LIGHTING
REALLY NECESSARY?
The first question
to ask is whether emergency lighting is really necessary at all. Very
often members of the public will not be visiting a historic building
after dark, or if they are it may be for a special concert or event which
takes place infrequently.
If there is no public
access to a historic building after dark and it is otherwise unoccupied,
there may be no need to provide any emergency lighting. If, on very infrequent
occasions, there are concerts or events, temporary emergency lighting
must be considered and should be located at the exits of the room and
on the fire escape routes.
The temporary emergency
lighting could consist of non-maintained, three-hour, emergency exit box
lights, which sit on the floor and are plugged into the nearest 13 amp
socket outlet. When the temporary exit signs are not being used, a special
plug-board should be provided so they can be charged all the time. Any
such arrangement has to be authorised by the local fire officer.
Another method of
providing temporary emergency lighting is by using hand torches. The ratio
of members of staff with hand torches to members of the public must be
high to satisfy health and safety regulations.
Emergency lighting
required for regular use, however, may not be needed throughout the building
and so could be restricted to one area. For example, if a ballroom is
in frequent use during the winter but other areas are not, the provision
of emergency lighting could be restricted to the ballroom itself, its
fire escape routes, and any other rooms connected with its use.
HOW TO ADAPT EXISTING FITTINGS
Emergency lighting
can be provided in many ways; it is not necessary to use the ice cream
tub on the ceiling and standard emergency exit signs, which look incongruous
in a historic building. A far more acceptable solution is to use as many
of the existing historic luminaires as possible.
The British Standard
for emergency lighting of premises other than cinemas and certain other
specified premises used for entertainment states that the illumination
level along the centre line of the escape routes should not be less than
one lux. As this is so low, a suitable level can be achieved without any
photometric data for the existing luminaires simply by over-lighting the
escape routes.
One of the most comprehensive
methods of providing emergency lighting is by the use of a standby battery
inverter unit, which enables the existing historic luminaires to be utilised.
The luminaires required for emergency lighting are all wired from the
same distribution board. A feed is taken from the standby battery inverter
unit to the distribution board, and the lighting circuits are wired through
a special relay unit to the various lighting points. Using the relay unit
enables ordinary light switches to be used to operate the emergency lights
just like normal lights, but when the power fails the emergency lights
will be illuminated regardless of whether the switch is on or off.
The feed from the
inverter unit to the distribution board, from the distribution board to
the relay unit, and the circuit wiring, must of course be as fireproof
as possible, and it is preferable to use MICC/PVC cables which give a
very high degree of electrical integrity. The last thing you want is for
the fire to burn through the cables causing the emergency lights to fail.
This way the emergency lights will last for the full three hours duration.
The exit signs can
be temporary or permanent. It is perfectly acceptable to have pieces of
stiff cardboard painted with the standard emergency exit legend and located
above the exit doors, provided there is an emergency light near enough
to the door to provide the correct amount of illumination on the sign.
In the same way, an emergency light can be located in all the necessary
locations detailed in BS 5266.
With this method of
emergency lighting all the luminaires are the same, and the aesthetic
appearance of the historic building is preserved.
An alternative method
is the use of remote, self-contained emergency battery packs which can
be non-maintained, maintained, or sustained, depending upon the task at
hand. The remote emergency battery pack must be located within one metre
of the emergency fitting and the wiring between them must also be fire-resistant,
to allow the emergency light to be illuminated continuously for the full
three hours duration in the event of a fire.
Remote, self-contained
emergency battery packs can be used to power a variety of different types
of emergency fittings, for example: low-voltage, 50 watt dichroic down-lighters;
table lamps where the remote emergency gear is located under the table;
existing historic luminaries; and a whole range of special luminaires
designed for a particular project, where the remote emergency control
gear box is located in a convenient store, a ceiling or wall void. Access
must be provided for maintenance of the remote control gearbox. Depending
on the type of gear box used the luminaires can be switched on and off as normal, but when the power
fails the emergency light will illuminate for the full three hours discharge
time.
When using this type
of gear pack it is very important to ensure that the red neon is mounted
in a visible position on the luminaire as a visual check that the gear
pack batteries are charging. There must also be maintenance access to
the gear pack and sufficient ventilation to prevent the batteries overheating.
Another method of
concealing emergency lighting is to install new, self-contained emergency
luminaires within existing ones, thus keeping the ordinary, emergency
and mains luminaires all the same. Many manufacturers supply both emergency
and mains luminaires of the same design. Consideration must again be given
to ventilation to prevent the batteries from overheating. If existing
historic luminaires are to be converted to contain the emergency battery
pack and control gear, they must be tested in accordance with the ICEL
Technical Guide 1004, which can be downloaded from the Industry Committee
for Emergency Lighting website, www.icel.co.uk.
INTRODUCING NEW EMERGENCY LIGHT FITTINGS DIRECTLY
Fibre optic lighting
can also be used as emergency lighting, with fibre optic cables concealed
above the skirting boards along a corridor to light the floor. However,
concealing the cables can be very difficult if the walls are not being
plastered as part of the building works, and setting the correct angle
can be a challenge. Fibre optic cables can also be taken up the walls
to door height level to light cardboard exit signs temporarily mounted
above the exit doors.
Fibre optic emergency
lighting systems can be virtually invisible as the fibre optic cables
used are only a few millimetres in diameter. However, the design and installation
of the system must comply with BS 5266-2 1998, BS 5266-4 1999 and BS 5266-5
1999, which can make it difficult to achieve the concealment and levels
of illumination required. Various companies provide computer programs
to calculate the level of illumination achieved by different types of
fibre optic cables.
Many refurbished churches
are being converted into multi-functional buildings with a variety of
uses such as concerts, nativity plays, meetings and play groups, all requiring
the use of emergency lighting. While it is often impractical to provide
an overall level of illumination as required by BS 5266, it is sometimes
possible to provide suitable emergency lighting under galleries.
Provision for emergency
exit signs can be made above the exit doors by installing a neat two amp,
three-pin socket outlet so that a self-contained emergency exit sign can
be plugged in above the door. The sign can be held in place by small cup
hooks above the door, then taken down after the event and kept charged
on a special plug-board, plugged into a 13 amp socket outlet in a store
room.
If an exit route is
through a vestry, the vestry can be lit using a fluorescent fitting with
a built-in emergency battery pack. Emergency lighting outside the emergency
exit doors is also required in accordance with BS 5266.
It is essential that
all the emergency lighting cables and equipment are installed very carefully
to ensure that the installation is completely invisible and does no harm
to the existing historic structure. It is also advisable to plan the installation
in such a way that it can be removed at a later date should the use of
the building change. For example, if it is unavoidable to run cables on
the surface of a fair-face stone wall, all the fixing for the cables should
be within the mortar joints between the blocks of stone, and the colour
of the sheath of the cable must match the surface upon which it is being
run. This way, if the cable ever needs to be removed, the damage could
be repaired by repointing the mortar joints, whereas if the cable had
been fixed into the stone blocks any damage could never be completely
concealed.
Installation often
entails the involvement a number of different people who must be consulted
about the location and installation of the emergency luminaires within
the constraints of the historic building and the current British Standards.
Often their requirements will conflict with one another!
The illustrations
give examples of what can be done with a little thought in order to fulfil
both aesthetic and safety requirements within the constraints of a historic
building. Above all, one must comply with the requirements of the British
Standards and obtain the local fire officer’s authority and approval for
the method of emergency lighting adopted, especially if the client requires
a licence for the activities within the historic building.
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