16th Edition (reference only) – NOW superseded by the 17th Edition IEE Regulations.

chapter 5

chapter 6

Installation requirements and characteristics
  2.1 - Introduction 2.5 - Low voltage generating sets
  2.2 - Safety requirements [Part 1] 2.6 - Standards
  2.3 - Definitions [Part 2] 2.7 - Undervoltage
2.4 - Assessment of general
-------characteristics [Part 3]

2.2.5 - Supplies for safety services

Safety services are special installations which come into use in an emergency, to protect from, or to warn of, danger and to allow people to escape. Thus, such installations would include fire alarms and emergency lighting, supplies for sprinkler system pumps, as well as specially protected circuits to allow lifts to function in the event of fire.

The special needs of safety circuits will often be required by authorities other than the IEE Regulations, especially where people gather in large numbers. For example, safety circuits in cinemas are covered by the Cinematograph Regulations 1955, administered by the Rome Office in England, Wales and Northern Ireland and in Scotland by the Secretary of State.

Safety circuits cannot be supplied by the normal installation, because it may fail in the dangerous circumstances the systems are there to guard against. The permitted sources of supply include cells and batteries, standby generators (see {2.5}) and separate feeders from the mains supply. The latter must only be used if it is certain that they will not fail at the same time as the main supply source.

[Chapter 56] contains six sections and a total of twenty-one Regulations, detailing the requirements for safety services. In effect, the circuits concerned must comply with all of the rest of the Regulations, and with some additional needs.

The safety source must have adequate duration. This means, for example, that battery operated emergency lighting must stay on for the time specified in the applicable British Standard (BS 5266). Since such installations may be called on to operate during a fire, they must not be installed so that they pass through fire risk areas and must have fire protection of adequate duration.

Safety circuits must be installed so that they are not affected by faults in normal systems and overload protection can be omitted to make the circuits less liable to failure. Safety sources must be in positions which are only open to skilled or instructed persons, and switchgear, control gear and alarms must be suitably labelled to make them clearly identifiable.


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Extracted from The Electricians Guide Fifth Edition
by John Whitfield

Published by EPA Press Click Here to order your Copy.

Click here for list of abbreviations