5.11Where residual current devices are required#

AS/NZS 3000 Clause 2.6 states that RCDs are not recognised as a sole means of basic protection but may be used to augment one of the means set out in AS/NZS 3000. The use of RCDs does not remove the requirement for correct circuit design using a variety of protection measures.

The requirements for additional protection by RCDs are included in AS/NZS 3000 Clause 1.5.6.3.; however, the clause most appropriate to Transport and Main Roads installations is Clause 2.6 and, in particular, Clause 2.6.3.2.1 of AS/NZS 3000.

1. a.final sub-circuits supplying socket outlets where the rated current of any individual socket outlet does not exceed 20 A, and
2. b.final sub-circuits supplying lighting where any portion of the circuit has a rated current not exceeding 20 A, and
3. c.final sub-circuits supplying directly connected hand-held electrical equipment, for example, hair dryers or tools.

Item c addresses hand-held directly-connected equipment such as hair dryers and hand tools. These are high-risk items as the connecting power lead is subjected to continual flexing and is seldom maintained.

RCDs may not be installed, as Clause 2.6.3.2.1 of AS/NZS 3000 states:

1. 5.where the disconnection of a circuit by an RCD could cause a danger greater than earth leakage current (see Section 5.12 following), or
2. 6.where all socket-outlets on a final sub-circuit are installed for the connection of specific items of equipment, provided that— …

RCDs must be installed in Transport and Main Roads installations in accordance with AS/NZS 3000; however, where the disconnection of the circuit by the RCD could cause a danger greater than the earth leakage current, or where all the provisions for specified items of equipment can be met, RCDs may not be required.

Where RCDs are installed for additional protection on specific equipment, only that equipment should be connected to the RCD – one RCD, one circuit.