It's lighting up time

The use of lighting in all security installations is well documented. Indeed it has become so commonplace as a deterrent and in supporting CCTV that in many installations it is now taken for granted. However the problem that the installer of lighting for security purposes has always been faced with is satisfying the client with suitable illumination when it can be so difficult to determine exactly what lighting levels may be the most effective.

In addition, the diversity of security lighting has always meant that we have never been able to produce standards to govern exactly how it is to be specified and installed. Therefore from the business point of view the security installer is unable to invoke a formal clause in relation to any standards policy so there is no particular route available to obtain maintenance contracts.

However the role of illumination specified for emergency lighting purposes is very different, since it is governed by legislation, workplace directives and building and fire regulations. Although emergency lighting is provided for safety when the supply to the normal lighting fails, it is also recognised as forming a fringe security issue alongside fire detection. For this reason security system installers have always been obliged to understand its architecture.

In the wider scheme of things it also offers excellent business opportunities. For those readers who may wish to do research with a view to moving into this sector – and for those of us who just want to recap – we will overview the system types.

Following this we can then consider the cabling, define the escape lighting routes and discuss how security and emergency lighting networks can be complementary.

System types
Emergency lighting can be expanded to become a major business activity because clients know how vital a role it plays in their operations. If the architecture of emergency lighting is understood it clearly provides installation companies with an extra dimension when visiting existing customers. Other installers may take a few prompts from our observations and then decide to gain greater levels of knowledge of the technology.

Remember that any business employing more than five persons is required by the Fire Precautions (Workplace) Regulations to carry out a fire risk assessment and provide a means of illumination for escape routes. There is also a need for most factories, buildings open to the public and those for multiple occupancy, to have emergency lighting and because there is a need for comprehensive maintenance schedules it offers good business prospects.

Nevertheless, as with any electrical system, there is no place for experimentation so the correct research of the subject and relevant training must be carried out in the first instance.

The first thing to appreciate is that emergency lighting is formed from one of four system types, namely:
The self-contained system uses the same cables as the general building mains wiring and is the most basic form. As the term suggests the luminaires have all of the elements within one unit to include the lamp, battery, charging electronics and mains failure indicator LED so they are easily cabled, replaced, extended and maintained. Therefore it is not difficult to initially become involved with this system alongside security lighting networks. The other three types are more specialist employing remote battery cubicles; or inverters (which convert the central battery to mains potential) so they must use protected cabling to supply the luminaires from the energy source and along the cable runs.

Cabling – a perspective
The cabling that we tend to find with self-contained systems is shown in Figure 1. The mains supply has been applied so as to generate a test circuit without a need to disconnect the general lighting. The use of a buzzer gives audible warning that the key switch is in the test position and ensures that the system cannot be held in discharge mode by accident.

The assembly can be made up in a grid box to include the general lighting switch, the test switch, the buzzer and a neon which is wired across the load of the internally fused luminaires. Notice that the emergency lights are wired in a parallel circuit looped in and out so that the test switch turns off the loop at source.

The buzzer illustrated is a mains version but a 12v DC type can be switched by a 240v relay coil through the switching contacts with the power derived from an extra low voltage power supply unit. With self-contained devices the wiring is not unlike security lighting cabling as it uses permanent live and neutral loops with appropriate switched lives. Therefore it employs a rather similar principle to providing the manual overrides on security demand lighting. In addition the cabling need only be PVC insulated and of the same conductor size as the general building wiring. This is because if the local wiring is destroyed the emergency lighting cables also expect to become detached. This will bring on the lighting for that area in the same way as a fuse rupturing or a circuit tripping out.

Escape lighting
The part of emergency lighting required to enable occupants to effect a safe means of escape is known as escape lighting. In practice it defines the escape routes, identifies problem areas and marks the location exit signs. The lighting must also ensure that fire alarm call points and firefighting equipment and such may be located. Points of emphasis for the positioning of luminaires are determined as the first part of the design procedure with additional luminaires then installed in areas of particular risk.

Luminaires for use in high risk task areas are rather different in that they must cater for potentially dangerous processes or shutdown procedures to be implemented. The design objectives are included in BS: 5266 and BSEN 1838. Many commercial buildings now feature permanently energised low energy internal lighting so that areas can be continuously monitored for security, and emergency lighting has a dual role to play in this.

Security & emergency
In practice we must continue to retain the actual emergency lighting and security lighting luminaires as separate identities because of legislation. However with the advancement of integrated networks and in recognition of the needs for energy management we can always utilise complementary technologies in that any one technique can provide benefits for others.

For example, an electronic security system can protect the cubicles and control equipment of central battery and inverter networks. This is vital because if these units are destroyed the emergency lighting becomes inoperable. In addition for high security risk areas the security lighting network or other mains driven security devices may be linked to the inverter if spare capacity is available. Therefore these will still work in the event of mains disconnection.

Using low energy maintained emergency luminaires ensures that lighting is always available even in the event that power cuts or faults occur. This is ideal because perpetrators are at a psychological disadvantage because of the very strategic overt role of the lighting as intruders remain uncertain as to whether they may have been observed. Offenders risk detection if the lighting remains on. Conversely they risk drawing attention to the area if the same lighting is vandalised and hence turned off.

It follows that deliberately trying to create mains faults to overcome security networks or to vandalise safety systems can be countered by emergency lighting amalgamated with auxiliary alarm relays.

The security industry has progressed and grown to the extent that the integration of systems is now big business and intelligent management is increasingly bringing together different technologies. Innovative networks can provide complex security solutions without any compromise and effective security and emergency lighting is no different in this respect.

The security installer can always benefit from combining parts of a number of lighting systems, no matter how small, to complement the role of others and to improve the overall level of the security and safety networks.