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RCDs

There have been some major changes regarding where and when an RCD is to be installed. In residential installations, all final sub-circuits are to be protected by a 30 mA RCD with no exceptions. Of course, the requirement for three final sub-circuits per RCD and the sharing of multiple lighting circuits across RCDs remains.

In non-residential installations, where there is a plug and socket connection to electrical equipment, the final sub-circuit shall be protected by a 30 mA RCD. Where there is fixed wiring direct to electrical equipment, consideration should be given to protecting that final sub-circuit with a 30 mA RCD. The existing exceptions remain in that where it is more dangerous to expose the final sub-circuit to nuisance tripping, the final sub-circuit can be protected by other means. Further to this, an exception has been added where electrical equipment is required to run continuously, in that case the final sub-circuit can be protected by other means. But all final sub-circuits for lighting shall be protected by a 30 mA RCD.

There used to be a reference to “alterations, additions and repairs” but we have removed “additions” as it is an “alteration”. Simply put, an alteration means that the electrical characteristics of the final sub-circuit have changed, for instance the addition of a socket-outlet in a new room changes the length of a cable run, and therefore it is necessary to put a 30 mA RCD on that circuit. Whereas, a repair is a like-for-like replacement of a broken or unusable accessory, meaning that the original protection for that final sub-circuit can remain and is not required to have 30 mA RCD protection. And finally, on RCDs, where all the circuit protection is to be replaced on a switchboard then all final sub-circuits from that switchboard need to be protected by a 30 mA RCD.

Medical Installations

There are many revised or new definitions and these provide a sound basis for all your discussion about design and installation. Using the definitions means that all parties in the discussion start at the same point. For instance, we have added a new definition “Accessible” and revised the definition of “Readily Accessible” to ensure clarity regarding medical installations and mounting of electrical equipment.

Further improvements to the emergency egress from a switch room have been made, with clearance requirements to one metre from accessible faces of a closed switchboard and 600 mm from open doors or racked-out equipment. The access/egress door from the switch room has also been increased in size. In an emergency, the increase in distances may save lives.

Mains Switches
Mains switches are an important part of any installation and it is essential that a mains switch is operated manually and is not controlled by electronic devices. New wording will clarify this aspect. The last thing needed in an installation is for an override of the mains switch by some programmable device. Manual switching could save lives.

What IP rating does electrical equipment need to comply with when exposed to the weather? A zone for external walls has been created to clarify what equipment can be used where. This zone extends at 30 degrees down from the edge of a verandah or eave to the exterior wall. Any electrical equipment within that 30-degree triangle is deemed protected and does not need an IP rating. All electrical equipment below that triangle requires an IP33 rating as a minimum. Meter boxes are excluded as they have historically been IP23. Any electrical equipment contained within the meter box enclosure does not need an IP rating.

SAI Global Wiring Rules

Mains switches are an important part of any installation and it is essential that a mains switch is operated manually and is not controlled by electronic devices. New wording will clarify this aspect. The last thing needed in an installation is for an override of the mains

Smith Jones

Director

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