Introducing CIBSE Guide K: electrical services

The eagerly-awaited CIBSE Guide K: Electrical services is due to be launched at a seminar in London on 20 January 2005. The Guide is intended as a reference source for engineers, architects, surveyors and other professionals who require easy access to the information on electrical services rather than as a textbook for those wishing to learn electrical engineering. Considerations on power supply, panels and cabling are closely related to other elements of building design and the Guide will provide a useful grounding in the fundamentals of electrical services.

Similarly, it is not intended that this Guide should be read from beginning to end in one go. Instead, the reader should dip into the relevant section that is of particular interest in respect of the project in hand. Guide K does not include large chunks of other documents such as IEE Wiring Regulations and British Standards but contains appropriate cross-references to the relevant sources of further information.

Section one, gives a brief overview of the various sections and provides a definition for the use of low voltage and high voltage because some technical documents still refer to medium voltage – it was decided to follow the definitions contained in BS 7671.

The section entitled ‘Legislation and standards’ provides a list of the most important legislation relating to electricity systems that is currently in force. In addition, it includes a description of BS 7671 which is better known as the IEE Wiring Regulations. Finally the section includes commentary on different European and International standards.

The ‘Load assessment’ section provides advice and guidance on assessing the load within the building. It describes the load factor, load assessment, load calculations and diversity and demand. There is also a sub-section on harmonics generated by equipment such as inductive luminaries, computers and uninterruptible power supplies.

Section four, on off-site supplies and on-site power generation, describes the regulatory environment of electricity supply following the Electricity Act 1989 and briefly discusses the wholesale electricity market and tariffs. It also covers sub-station planning and construction and the options for on-site generation including testing and commissioning.

Following logically on from power supplies is section five: High voltage switchgear and distribution. The section covers the design of hv systems, types of sub-stations, environmental considerations, types of switchgear and gives specification guidance.

The section also includes five pages on system protection. The hv section is completed by examination of hv cables and consideration of safety aspects, operation and maintenance.

Working through the electrical system, after hv switchgear comes transformers and this is the subject of Section six. The section starts with fundamental principles and covers the different types of transformers, information required for specification, different types of winding configuration, cooling and so on.

Section seven covers low voltage switchgear and distribution. The ten pages in this section provide a comprehensive look at lv distribution, switchgear and protection.

At 24 pages, one of the most comprehensive sections in the book is Section eight covering building wiring systems. Types of circuit, different types of cabling, selection criteria, types of cable construction and containment systems are all covered.

Section nine, ‘Uninterruptible power supplies’, at 28 pages is the longest in the Guide. It is effectively two sections knitted together, the first being uninterruptible power supplies, and the second being batteries.

Section 10 is simply titled ‘Earthing’ is very comprehensive and contains useful information on touch voltage and fault currents.

Section 11 will probably be the most mysterious to the majority of readers, as its title is ‘Electromagnetic compatibility’. It covers the EMC Directive and the obligations imposed through law. It also covers the electromagnetic compatibility (emc) regulations and deals with how emc compliance can be obtained on projects, particularly those with electrically noisy equipment.

Section 12, is on inspection, testing, operation and maintenance. It provides essential and thorough guidance on the whole post-installation procedure.

Guide K is a 146 page, A4-size document that will be a useful resource in the offices of a range of users. It is not a text book but will be a useful reference source for a variety of professionals.

This first edition is exactly that: the document will be an organic animal, growing and changing with the demands of the readers, and reflecting changes in techniques and equipment as time goes on.

• For more information on the seminar contact CIBSE Events on 020 8675 5211 or jsinfield@cibse.org