Part one of this article, which appeared in the last issue of Wiring Matters, looked at the requirements within BS 7671 relating to the provision of information considered necessary for the safe and effective use of electrical installations. In this part we will be concentrating on those requirements relating to the provision of information which apply to safety services; special installations and locations; and inspection, testing, certification and reporting.
Safety services
Within BS 7671, Chapter 56 contains requirements for safety services such as emergency lighting, fire detection and alarm systems and industrial safety systems. Regulation 560.7.5 requires that any switchgear and controlgear should be clearly identified to indicate its purpose. Such clear identification is essential as switch/controlgear for emergency services must be placed in a location where it is only accessible by skilled or instructed persons. This may, in many cases result in it being placed remotely from the equipment or circuits being controlled. It is a general requirement that the purpose of each device provided to act as an isolator is, as a result of its physical location or through labelling, clearly understandable (537.2.2.6 refers). As such, except for the most straightforward of installations, it will be necessary to label or otherwise identify both the isolator and the item of equipment wherever an isolator is placed remote to the item of equipment being controlled.
In many cases, arrangements for safety services may need to be understood or, in the case of fire rescue service lifts and communications systems, operated by persons who are not familiar with the building or the installation therein. As a result Chapter 56 contains a number of requirements designed to make the information necessary for the safe and proper use of safety services readily available. These requirements are described below:
- Full details should be given of all electrical safety services within the building or location and should be displayed close to the relevant distribution board (560.7.9 refers). This information should be conveyed as clearly as possible and as such a single line schematic diagram would be sufficient in some cases.
- Any drawings relating to the safety services should be displayed at the origin of the installation. These drawings should clearly identify the location of
– All items of electrical control equipment and distribution boards. Any equipment identification designations used should be clearly stated on the drawings
– each item of safety equipment. The particulars and purpose of each item of equipment and the relevant individual circuit identification designation being clearly stated
– any special switching or monitoring equipment associated with a power supply for a safety service including visual or audible warning equipment (560.7.10 refers) - A schedule of all items of current using equipment (as defined in Part 2 of BS 7671) which is connected to the safety power supply. Characteristics such as rated current (as defined), starting time and starting current should be stated for each item. Where convenient, this information may be given on the circuit diagrams.
- The operating instructions for all items of safety equipment and electrical safety services should be made readily available. These instructions should be specific to the actual installation in question as an aid to the operation of the safety services therein (560.7.12 refers).
It will of course be necessary to comply with the requirements of other relevant standards relating to safety services too. By way of example, BS 5839-1: 2002 (2008) Fire detection and fire alarm systems for buildings – Part 1: Code of practice for design, installation,
commissioning and maintenance.) contains a number of requirements pertinent to this article such as:
- With the exception of the main isolator serving the whole building, any isolator or protective device that could be used to isolate the supply to the fire alarm system should be clearly labelled:
– “FIRE ALARM” where a protective device not containing a switch serves only the fire alarm system.
– “FIRE ALARM. DO NOT SWITCH OFF” where a switching device, whether incorporating a protective device or not, serves only the fire alarm system.
– “WARNING. THIS SWITCH ALSO CONTROLS THE SUPPLY TO THE FIRE ALARM SYSTEM” where a switch disconnects the supply to both the fire alarm system and other circuits (clause 25.2 f refers). - Clause 40 requires adequate records and other documentation to be provided to the user or purchaser. This would include certificates covering the design, installation and commissioning of the alarm system; an operation and maintenance manual for the system; as fitted drawings and a log book in which to record maintenance and testing activities, fire alarm signals and false alarms.
To view the full article from the IET's Wiring Matters Autumn 2009, click on the attachment below...