The potential for installation and maintenance work in the security industry is growing rapidly and opportunities are opening for electrical contractors. But are you ready? The ECA aims to help.
The security industry is big business and growing. Traditionally, the installation and maintenance of closed-circuit television (cctv) surveillance equipment fell to specialist security installers, but opportunities for electrical contractors are increasing. What is involved? There are many factors that must be considered for security systems. In order to help firms prepare, the ECA has published the Code of practice for closed circuit television installations. This gives guidelines for the planning, design, installation, commissioning and routine and corrective maintenance of cctv systems for security surveillance. It is not intended to help define the level of surveillance needed, but to promote a professional approach so that the end-user has available sufficient information to select a system that meets their needs.

System specification
The specification of a cctv installation depends on several factors, including the type and level of surveillance wanted and the type and use of the area or building that is to be observed.

In order to establish these factors the end-user must be consulted at the initial design stage, as their objectives and expectations are fundamental to the system's success. At this stage also, the views of insurers, police and specialist security consultants should be taken into account if applicable.

It is recommended that all the interested parties meet on site as early as possible to establish the surveillance needs. If this is not possible, each party should visit the site and make their recommendations and views known before the installation begins.

Provisions for future system expansion should be considered at the design stage so that equipment can be selected that would make this possible.

A written specification should be provided for the client or end-user. This should contain precise information, including the type and location of each camera and the specific zone surveyed, which can be defined on drawings. The client should sign a form of agreement to this specification prior to the installation.

Providing power
Power supplies must be compatible with the equipment being installed and be capable of providing the maximum system load under normal operating conditions.

All supply equipment should be installed in secure locations, preferably inaccessible to the public. For high security surveillance areas standby supplies may be needed.

There are several options available for the video signal transmission medium: co-axial cable, twisted pair cable, microwave and radio frequency, fibre optic cable, infra-red, laser and network. Which medium is chosen is dependent on several factors, including:

  • the compatibility with cameras and control equipment;
  • the distance to be transmitted over and acceptable signal loss;
  • the complexity of the system;
  • the reliability of transmission.

Each of the mediums has different features that must be considered, for example co-axial cable transmission is limited in length by signal losses and twisted pair transmission often needs precise alignment of transmitters and receivers and a licence to transmit.

Cabling for power supply and transmissions should be segregated. This should be maintained at entry points to equipment by using separate entry apertures.

The cabling should be adequately supported and any bends should be of the correct radii so that operational integrity is not impaired.

Connectors used for the interconnection of cables and conductors should ensure good electrical continuity and adequate mechanical strength. All terminations of cables and conductors should include appropriate identification to facilitate future maintenance.

The cable routes should be planned so that wherever possible the shortest cable lengths are used to link equipment. However, connections to moving cameras should have enough flexibility to prevent tension on cables and connections, and routes should be planned to avoid public access areas where possible.

If it is necessary to install cabling in a public area it is vital that the appropriate mechanical protection is installed to prevent tampering. Such protection should also be included on cables installed at low level, in external or harsh environments, leading into accessories and within finished wall surfaces.

Lights, camera, action
The camera and lens chosen must be compatible and suitable for the area that has to be surveyed. They should take into account the maximum and minimum lighting levels, compatibility with the surrounding lighting and the ambient conditions in the area of operation. For general surveillance, cameras should have a video output that comprises of 625 television lines as standard.

When positioning cameras, care should be taken to make sure that direct light sources are not in the field of vision. Where ambient lighting can be subject to constant variations over a wide range of illumination levels, lenses should include a controlled iris to compensate for the changes and to stabilise the video signal over the working range.

Camera fixing brackets should be attached by methods such as expansion bolts, plates and bolting arrangements, or screws and wall plugs for small, indoor cameras. For outdoor fixings, fasteners plated to avoid rusting should be used. It should be noted that self-tapping screws are regarded as unsuitable for fastening to metal clad structures.

When locating pan-and-tilt cameras it should be ensured that movement is not impeded in any direction. Where appropriate, limit stops should be included to take account of any identified privacy issues. Regard must be taken to prevent misuse by unauthorised persons and to the safety implications of maintenance.

The upgrading or addition of associated lighting should be considered. This lighting is intended to ensure that the cctv system operates effectively in the dark; it may emit in the visible or non-visible spectrum. Lighting should be compatible with the camera and lens chosen and may be colocated with this equipment.

The contract for installation of lighting is in some cases undertaken by a separate specialist contractor so details should be agreed and recorded.

The control room
The control viewing and recording equipment is the hub of the system in the client's eyes. This equipment may be located in a designated control room or otherwise, but it should generally be positioned in a secure area with no public access.

Care must be taken when choosing monitors and camera switching/control equipment to ensure simple and optimum operation by the end-users.

Systems should preferably incorporate automatic switching, zoom pan-and-tilt and other automatic functions with manual override facilities for operator intervention under alarm conditions.

The effectiveness of a system is dependent on the operators ability to act quickly in response to an alarm event. To ensure that this is optimised no operator should be responsible for more than ten monitors and the layout of consoles should consider operator comfort: monitors should be at eye level and without areas of glare.

Ongoing maintenance should be considered and the system designed so that the loss of one receiving channel etc has minimal impact on security. It should be possible to have at least 90% operational capacity during maintenance work.

On high risk sites, the stock-holding of essential spares should be considered so that any failure during normal service can be quickly resolved.

System handover
It is important to verify that the specified system requirements have been satisfied at handover stage. Commissioning should include a visual inspection, electrical testing and functional testing of the complete system.

For large systems or those installed in stages, commissioning can be carried out at the different stages of completion.

The visual inspection should include the identification of conductor and cable terminations, checks that the labelling at the supply source is correct and the fixings of camera assemblies etc are adequate. The results of these checks should be documented.

The functional testing stage should verify that the operational needs specified are satisfied by the system. This should include checking of the camera view and functions, triggering device functions, the focus, clarity and stability of real-time and stored images and all other relevant system functions and equipment.

For good practice, each item of equipment should be labelled with warning notices if the voltage supplied or present exceeds 50 Vac or 120 Vdc. Where movement occurs under normal operation, for example with a pan-and-tilt camera, a warning notice should be fixed adjacent to the equipment.

A logbook should be given to the customer at handover, with instructions and training in the system's correct use. A handover certificate should also be provided, which will certify that the system specifications have been met and include details of any alternative equipment that has been installed plus fault call-out procedures.

Companies installing such systems must also comply with BS 7671: Requirements for electrical installations, BS EN 50132-7: Alarm systems – cctv surveillance systems for use in security applications – application guidelines, and other relevant and applicable standards.

Copies of the code have been distributed to members of the ECA's fire and security sector. Further copies are available priced £2.50 from the membership department. Tel: 020 7313 4800.

Source

Electrical and Mechanical Contractor