Description of BS 5490:1977 1986

This standard provides a system for specifying the enclosures of electrical equipment on the basis of the degree of protection provided by the enclosure. It is applicable to enclosures where the rated voltage of the equipment inside the enclosure does not exceed 72.5 kV.

It also specifies type tests to check the performance of the various classes of enclosure.

The type of protection covered by this system of classification is as follows:

1. Protection of persons against contact with or approach to live parts and against contact with moving parts (other than smooth rotating shafts and the like) inside the enclosure and protection of the equipment against ingress of solid foreign bodies.

2. Protection of the equipment inside the enclosure against harmful ingress of water.

Notes 1. — The protection of moving parts external to the enclosure, such as fans, is a matter for the relevant Technical Committee.

2. — In this standard, the tests are conducted with fresh water.

This standard deals only with enclosures that are in all other respects suitable for their intended use and which, from the point of view of materials and workmanship, ensure that the properties dealt with in this standard are maintained under the normal conditions of use.

The standard does not specify degrees of protection against mechanical damage of the equipment, risk of explosions, or conditions such as moisture (produced for example by condensation), corrosive vapours, fungus or vermin.

Fences or guards external to the enclosure which have to be provided solely for the safety of personnel are not considered part of the enclosure and are not dealt with.

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