Isolation and functional switches for inductive loads

NECA Technical have received a number of questions relating to the category of switching devices required for inductive loads, such as motors and fluorescent lighting.

A functional switch is a device that is required for operational control of electrical equipment only and is not installed for safety reasons as per clause of AS/NZS 3000:2018.

Functional switches must be suitable for the duties they are required to perform. Therefore, if a functional switch is required to control loads that have low power factor, then a de-rating factor needs to be applied. The need for the application of a de-rating factor is not required if the device has been designed for the purpose, e.g. switches having a utilisation category of AC23A meet this requirement as per exception to clause of AS/NZS 3000:2018.

Isolation switches that are installed to isolate items of equipment or appliances for maintenance, and not for operational control of the equipment or appliance, do not need to be category AC23A. However, if installed in a location where it may inadvertently be used to switch the full load current, then an appropriately rated switch or category AC23A switch should be installed.