What's up, Buzz? RCDs!

The main change is to the application of RCDs in domestic installations. All final sub-circuits in a residential installation, no matter the amperage or number of phases, are to be 30mA RCD protected. In general, the changes made now require fixed or stationary electrical equipment, such as a hot water service, an air conditioner, cook top, oven or range to be protected by a 30mA RCD. 

Where a whole switchboard is being upgraded to replace existing protection then that switchboard is to be brought up to date with RCD protection.

A repair is a like-for-like replacement and as such does not require the installation of an RCD for that final sub-circuit. This extends to a replacement of an existing socket-outlet with a multi-socket-outlet. The replacement of halogen lights with LED lighting is also seen as a repair.

An alteration however is a change to the existing final sub-circuit and as such requires a 30mA RCD at the switchboard (or a 30mA socket-outlet RCD at the start of an extended circuit).

In non-residential installations, all final sub-circuits, up to and including 32A, multi-phase and lighting, are to be 30mA RCD protected. There are however two scenarios to this requirement.

If the electrical equipment is fixed wired direct in that installation, meaning that it cannot be moved unless by skilled persons (wiring disconnection), the requirement for an RCD is a consideration only.

If the electrical equipment is plug and socket connected in that installation, meaning that it can be unplugged and moved by unskilled persons (inadvertent damage to the equipment and insulation may occur, as well as unsafe equipment being plugged into the socket), the requirement for an RCD is a mandatory one.

There are several exceptions to the non-residential installations that exist already but a new one has been added. If the owner/operator deems that a piece of electrical equipment must not be exposed to nuisance tripping, as it may cause economic or personnel disruption for example, then the RCD can be left off the final sub-circuit.

As with any of these exceptions it is required to have over-current protection at the switchboard, mechanical protection of the cable, wiring connection marked to state that RCD protection is not provided.

Home-care medical installations are now referred to AS/NZS 3003 Electrical Installations – Patient Areas rather than duplicate information between both installation standards.