This standard applies to manually operated 3-pole oil switches for three-phase a.c. systems. The standard ratings are set out in Table 1. It does not apply to switches that can be opened or closed by power, to oil isolators, to oil selectors, to combinations of switches and fuses in series, or to switches intended for making and breaking circuits frequently at short intervals (e.g. starting switches). Neither does it include the additional requirements necessary in connection with flameproof enclosures.

BS 2631:1955 - Equivalent