A summary of the main RCD requirements under the new Wiring Rules

Since the release of AS/NZS 3000:2018, Multi Service Group have been receiving a number of enquiries regarding the RCD requirements under the new rule book.

Below is a concise summary of the requirements.
1. RCDs shall be of a fixed setting type with a rating not exceeding 30 mA
2. In all installations where more than one circuit is installed and there is more than one lighting circuit, the lighting circuits shall be distributed between RCDs
3. In domestic/residential installations:

a. The number of circuits protected by one RCD shall not exceed three
b. Where there is more than one final sub-circuit, a minimum of two RCDs shall be installed
c. All final sub-circuits shall be RCD protected
d. The RCD shall be installed at the switchboard from where the final sub-circuit originates
e. RCD protection is not required where only repairs are undertaken

4. Non-domestic (commercial) installations:

a. Socket outlet and lighting circuits ≤ 32 amps require RCD protection
b. Unless the wiring has additional mechanical protection, the RCDs are to be installed at the switchboard from where the final sub-circuit originates
c. RCD protection is not required where:

i. Only repairs are undertaken
ii. Disconnection of the circuit would create a greater danger (traffic lights)
iii. The final sub-circuit is used for specific equipment where tripping is unacceptable, provided that the outlet is in a position not likely to be accessed and is clearly marked

5. Alterations and switchboard replacements (all installations):

a. If an alteration to an existing circuit or a switchboard replacement is undertaken, RCD protection is required
b. Where socket outlets are added to an existing circuit, the RCD need only be installed at the commencement of the new additional wiring
c. Additions to existing lighting circuits without RCD protection do not require RCDs to be fitted
d. Where all of the circuit protection on a switchboard is replaced, RCD protection is required
e. Repairs only to a circuit do not require RCD protection to be installed. This includes the changing of a GPO from a single to a multi-point