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9
Table 53.2 identifies that circuit breakers to BS EN 60947-2
are suitable for isolation. These are commonly used as outgoing
devices in distribution boards and can be used as isolation
devices for individual circuits.
The table below gives guidance as to whether the neutral
conductor needs to be switched or not.
Table 53.2
BS 7671 also requires that the device used for isolation is
designed and/or installed so as to prevent unintentional or
inadvertent closure. Usually this means that you need to fit some
kind of locking mechanism to the device.
IEE Guidance Note 2 gives more detailed guidance on isolation
and switching.
Isolation requirements of Neutral Conductor
Origin
Downstream
Use by
ordinary
persons
Use by skilled
or instructed
persons
Use by
ordinary
persons
Use by skilled
or instructed
persons
SP TP SP TP SP TP SP TP
TN YES NO* NO* NO*
NO NO NO NO
TT YES YES YES YES YES YES YES YES
Note* There should be some means of disconnecting the neutral by means of a bolted link