5.12AS/NZS 3000 Clause 2.6.3.2.1 Exception 5#

5.12.1General comments#

The Electrical Safety Act 2002 requires that an electrical installation be electrically safe, which means that the electrical risk to the person or property is as low as reasonably achievable, having regard to the likelihood of harm and likely severity of harm.

AS/NZS 3000 Clause 1.1 states that guidance is provided so that the electrical installation will function correctly for the purpose intended.

The intent of these documents is that electrical installations are fit for purpose and function with a reasonably low level of risk. It is within this framework that particular applications of RCDs within the Transport and Main Roads infrastructure are considered.

Exception 5 to AS/NZS 3000 Clause 2.6.3.2.1 states that the requirement for additional protection by RCDs need not apply where the disconnection of a circuit by the RCD could cause a danger greater than the leakage current.

To determine whether the disconnection of the RCD through nuisance tripping could cause a danger / risk greater than the earth leakage current, a risk assessment must be carried out.

A general risk assessment has been carried out for a number of electrical installations to determine if this exception could apply. This assessment is included in Section 5.16.

These consider the risk to a person from vehicular or criminal activity, compared with the risk to a person from an electrical installation, using the parameters of the likelihood of harm and likely severity of harm.

5.12.2Road lighting installations#

From the risk analysis, road lighting installations are considered to comply with the requirements of Exception 5.

5.12.3Traffic signals installations#

From the risk analysis, traffic signals installations and supporting communications equipment are considered to comply with the requirements of Exception 5.

Safety-related devices supporting traffic signal installations, such as CCTV, Field Processors (FP), and Network Terminal Units (NTU) assist Traffic Management Centre (TMC) operators in promptly responding to failures of traffic signals. If these devices cease to function due to nuisance tripping, it may lead to delayed response to a traffic signal failure event. The risk is magnified for busier intersections; therefore, these supporting communication devices are also considered to comply with the requirements of Exception 5. All non-RCD protected socket outlets must be clearly labelled.

5.12.4Pathway lighting installations to AS/NZS 1158#

From the risk analysis, pedestrian pathway lighting installations to AS/NZS 1158 are considered to comply with the requirements of Exception 5.

5.12.5Safety related traffic management devices#

From the risk analysis, safety related traffic management devices are considered to comply with the requirements of Exception 5.