New standard for selection of cables

A new standard for the selection of cables was published by SAI Global in late 2009 and will be used by Queensland’s Electrical Safety Office as the basis for ensuring compliance with electrical safety legislation on work performed from 1 June 2010.

The standard is entitled AS/NZS 3008.1.1:2009 (Electrical installations - Selection of cables - Cables for alternating voltages up to and including 0.6/1 kV – Typical Australian installation conditions).

It sets out a method for cable selection for those types of electrical cables and methods of installation that are in common use at working voltages up to and including 0.6/1 kV at 50 Hz a.c.

Three criteria are given for cable selection:
(a) Current-carrying capacity
(b) Voltage drop
(c) Short-circuit temperature rise

This standard provides sustained current-carrying capacities and voltage drop values for those types of electrical cable and installation practices in common use in Australia. A significant amount of explanatory material is also provided on the application of rating factors that arise from the particular installation conditions of a single circuit or groups of circuits. Also, provided in Section 5 is information on cable selection based on short-circuit temperature limits.

This standard recommends that it apply to installations made or carried out after the date of publication on 26 October 2009, but it is recommended that it not be applied on a mandatory basis until six months after the publication date.

Queensland’s Electrical Safety Office will be using this standard as a basis for ensuring compliance with the electrical safety legislation on electrical work performed from Tuesday 1 June 2010 with the following exceptions:

• electrical work commenced under the former standard (AS/NZS 3008.1.1:1998) prior to 1 June 2010 may continue;
• electrical work quoted under the former standard (AS/NZS 3008.1.1:1998) prior to 1 June and for which a contract has been awarded may be performed under the former standard;
• electrical work designed under the former standard (AS/NZS 3008.1.1:1998) prior to 1 June for projects (e.g. like shopping complexes, large residential & industrial buildings), may be performed under the former standard; and
• the new standard (AS/NZS 3008.1.1:1998) prior to 1 June may be applied to the above circumstances where it does not cause onerous changes or costs.

A copy of the standard can be purchased from SAI Global at www.saiglobal.com