AS 3000 2007 New wiring rules for electrical work (Nat)

AS/NZS 3000:2007 - Wiring Rules was published in November 2007 and will become mandatory through each State & Territory’s regulations for electrical installation during 2008.

The Revision Process

A joint Australian/New Zealand Technical Committee EL-001 – Wiring Rules produced the revised edition of AS/NZS 3000. The re-drafting process started late 2004. A public comment draft was issued in March 2006 with 2500 comments received.  A final draft was issued in mid-2007, and was approved for publication in late 2007.

Model Format

The format of the new wiring rules comprises two-parts.

Part 1 provides the uniform essential elements that constitute minimum regulatory requirements for safe electrical installations. Part 1 is essentially the same as Section 1 of the 2000 edition.  It allows for the development of new methods and the acceptance of alternative designs and installation practices to those given in Part 2.

Part 2 provides installation wiring practices that are deemed-to-satisfy the fundamental requirements in Part 1. Part 2 also provides guidance on “good design” practices that assist compliance with the “fit for purpose” approach of Part 1.

Major differences from 2000 edition are:

• The two-part structure as mentioned above;
• Layout revised to group similar requirements into the same section;
• Verification (inspection) procedures moved to the last section (Section 8);
• more examples, diagrams and appendixes;
• reinstated guidance information from AS 3000:1991 edition, such as simplified cable ratings, number of cables in conduit and other information;

The Preface sets out 56 major changes from the 2000 edition but there are other minor changes as well.

The key areas of new or amended standards which will affect housing relate to:

• New and modified definitions;
• Access to switchboards updated;
• Additional protection by Residual Current Devices (RCD) and their arrangement;
• Protection against arcing faults in large switchboards;
• Discrimination between circuit protective devices;
• Recessed luminaire clearances;
• Bonding of reinforced concrete near baths and showers; and
• Minimum size of main neutral and “PEN” conductors.

Most relevant for home builders are the “new” recessed luminaire clearances and the bonding of reinforced concrete near baths and showers. More details are set out below on these two issues

Recessed luminaire clearances

Clause 4.5.2.3 now requires that recessed luminaries and auxiliary equipment be installed in a manner designed to minimise temperature rise and prevent the risk of fire (generally below 93o C).

The following options are given to satisfy the requirement:

• Manufacturer certified luminaires that do not heat up;
• Luminaires with a suitable fire-resistant enclosure (hood);
• Compliance with clearances specified by the manufacturer;
• Default clearances between luminares and insulation of 200mm (Note - the clearances given in Fig. 4.7 are default clearances and only one of the options to comply.)
• Provision for thermal insulation
• First two options above are where leaves and vermin are likely.

Bonding of reinforced concrete in showers and bathrooms

Clause 5.6.2.5 sets out a new requirement for showers and bathrooms to minimise the risk associated with the occurrence of voltage differences that may occur between electrical equipment connected to the electrical installation earthing system and any conductive piping (including taps etc.). The requirement states:

“Any conductive reinforcing within a concrete floor or wall forming part of a shower or bathroom shall be bonded to the earthing system of the electrical installation to avoid any potential differences that may occur between the conductive piping (including taps, drain, etc.) connected to, or in contact with, the electrical installation earthing system and the concrete floor or wall.

An equipotential bonding conductor, in accordance with Clause 5.6.3, shall be connected between the reinforcing material and any part of the earthing system within the room.”

The notes to the clause indicate that reinforcing mesh or tie-wires laid in the floor and connected to the equipotential conductor may be used. This requirement is not for existing concrete floors or walls, although the practice is encouraged wherever practicable. It is suggested that the builder coordinate between the trades to ensure the proper placement of the earthing system for the showers and bathrooms.

For further information HIA members can contact HIA’s Building Services staff on 1300 650 620 or hia_technical@hia.com.au.

To find out more on becoming a HIA member, contact 1300 650 620 or enquiry@hia.com.au.

Ref No. BCA 08-02  

The above is intended to provide general information in summary form. The contents do not constitute specific advice and should not be relied upon as such. Formal specific advice should be sought by members with respect to particular matters before taking action.  ABN 99 004 631 752