Standards Update

In short, these amendments related to RCD’s being installed at the socket outlet in patient areas in hospitals which is necessary for example where hospital staff need to be able to reset medical equipment connected to a patients care. This RCD configuration is allowed in patient areas subject to the circuit being mechanically protected or installed with earthed armouring / screening to protect the circuit. Refer to AS/NZS 3000:2018, Clause Location of RCD protection and AS/NZS3000:2018, Clause Protection methods for full details of the requirements.

A dispute arose to the interpretation of these clauses when Queensland Health issued an advisory note and safety notice indicating that, by their interpretation, wiring in final subcircuits with the RCD located remote from the switchboard required mechanical protection to WSX3 for the entire length of the final sub-circuit, as opposed to the recognised common installation practices associated with wiring in ceiling spaces. As a result the issue was raised with EL-001, the Standards Australia Committee with responsibility for the Wiring Rules.

Standards Australia on 24 May 2024 released the following ruling on behalf of the EL-001 committee, which reads as follows: 

Ruling to AS/NZS 3000:2018 Electrical installations (known as the Australian/New Zealand Wiring Rules) 
Enquiry A 

Can the Exception in Clause be applied, if methods of protection against mechanical damage complying with either Clause (a) or Clause (b) are used in conditions required by either Clause or Clause 

Ruling A 
Yes. The Exception to Clause allows an alternative location of an RCD in some cases. The “trigger” condition that permits the application of the Exception is as follows: 
“Where the wiring system is installed with additional protection against mechanical damage, complying with the requirements of Clause or Clause”. 

These words have been interpreted to mean that the entire cable route length of the wiring system must have the stated protection. This interpretation is not the intent of the exception’s “trigger” condition. 

This is taken to mean that, final sub-circuit wiring that is otherwise installed to AS/NZS3000:2018 in a ceiling space without the risk of mechanical damage, is not required to be protected to WSX3 in those spaces.  

This article was publised on 31 May 2024.