System Listings

Power Services

System Overview
Power services is the phrase generally given general electrical equipment around the building. The system may cover such items as:

• Socket outlets & accessories.
• Machinery supplies and isolators.
• Equipment supplies.
• Cabling serving the above.

A building will always have some form of power services requirements.

Power services will generally be served via circuits fed from a final circuit distribution board

Systems Available and Applications
Power can be delivered to equipment in a variety of means and many of the common wiring systems can be utilised.
It is common for small power circuits to be wired in a form of a ring main.

The following items of equipment are commonly installed.

• Socket Outlets. These are generally the primary means to deliver electricity to portable equipment throughout the building. There are many types of socket outlet available depending upon the style of the building, type of equipment served and environmental conditions. The familiar 13A Switched Socket Outlets (SSO) is only suitable for internal use. External or Damp locations require outlets that have suitable ingress protection.

• General Accessories. Apart from socket outlets, many form of accessories are available to enable connection and control of equipment. The Fused Connection Unit is a popular means to connect fixed small equipment.

• Isolators - Isolators or Switchfuses are generally used to serve larger items of equipment. Isolators for final circuit use are available in flush and compact form - more attractive than their larger relatives used in the mains intake.

• Floor boxes - Where a suspended floor is present it is common for outlets to be installed in floorboxes. These may be served by conduit, trunking or powertrack systems.
  

• Busbar systems are much used in industrial buildings to serve power services.
  

• Small power accessories are often mounted on a perimeter trunking system. This may have internal busbars.

Legislation & Guidelines

British Standards.

Also refer to The British Standards Institution

• BS 1363:1984 "Specification for 13 A fused plugs and switched and unswitched socket-outlets" Conditions of use, definitions, construction and tests, including those related to non-rewirable plugs and portable socket outlets. Appendices include construction of a calibrated link and a test plug for the temperature rise test.
  
• BS 1362:1973 "Specification for general purpose fuse links for domestic and similar purposes (primarily for use in plugs)" Performance, dimensions, marking, tests for fuse links of any current rating not exceeding 13 A at 250 V a.c. For use in plugs complying with BS 1363, the preferred current ratings are 3 A and 13 A.
  
• BS 3676:Part 1:1989 "Switches for household and similar fixed electrical installations". Specification for general requirements and tests for manually operated general purpose switches with a rated voltage not exceeding 440V and a rated current not exceeding 63A, with particular reference to safety in normal use.
  
• BS 5733:1979 "Specification for general requirements for electrical accessories". Electrical wiring accessories for installation purposes, not specifically covered by other British Standards, for use in single phase a.c. or d.c. circuits, for voltages between conductors exceeding extra low voltage but not exceeding 250 V, and current not exceeding 45 A.
  
• BS 7671:1992 "Requirements for electrical installations". IEE Wiring Regulations. Sixteenth edition. This is the all encompassing "Bible" in relation to the design, installation and use of electrical installations and equipment in buildings.
  

International Standards

See also IEC search page

• IEC/TR 60536 (1976-01) "Classification of electrical and electronic equipment with regard to protection against electric shock". Defines classes of electrical and electronic equipment regarding protection against electric shock. Applies to equipment intended for connection to an external power supply with voltages up to 440 V r.m.s. between phases and 250 V r.m.s. between phases and earth, for use by the general public in homes, offices, workshops, schools, farms and the like, and for medical and dental purposes. Has the status of a technical report.

• IEC 60364 "Electrical installations of buildings " - Comprehensive document covering all aspects of electrical installations within buildings

Legislation

• Health & Safety at Work Act 1974 - Massive item of legislation which encompasses all aspects of Health & Safety in the workplace. This has been constantly added to over the years. It now comprises and references a whole series of separate regulations and codes of practice documents
  
• Electricity Act 1989 - In the words of the official HMSO title. "An Act to provide for the appointment and functions of a Director General of Electricity Supply and of consumers' committees for the electricity supply industry; to make new provision with respect to the supply of electricity through electric lines and the generation and transmission of electricity for such supply; to abolish the Electricity Consumers' Council and the Consultative Councils established under the Electricity Act 1947; to provide for the vesting of the property, rights and liabilities of the Electricity Boards and the Electricity Council in companies nominated by the Secretary of State and the subsequent dissolution of those Boards and that Council; to provide for the giving of financial assistance in connection with the storage and reprocessing of nuclear fuel, the treatment, storage and disposal of radioactive waste and the decommissioning of nuclear installations; to amend the Rights of Entry (Gas and Electricity Boards) Act 1954 and the Local Government (Scotland) Act 1973; and for connected purposes."
  
• Supply regulations 1989. - A set of regulations relating to the obligations of the Regional Electricity Companies and the supply of electricity to both industrial & domestic consumers.
  
• Electricity at Work Regulations 1989 - Regulations covering the whole aspect of ensuring that the workplace is safe in regards to the use of electrical equipment. (a part of the H&S at Work act)
  
• Construction (design & management) regulations 1994 - Another wide reaching set of regulations which cover the whole process of construction safety. It focuses on carrying out risk assessments and altering the design or management process to account for such risks. Again this forms part of the H&S at work act 1974.

Related Links

Links relating to the design and installation of small power services can be found here

Manufacturers

Most of the above illustrations have been provided by MK Electric Ltd to whom thanks is expressed. Other manufactures are listed here