AS/NZS 3000: 2018 Wiring Rules Standard for RCDs in Commercial Buildings

New clause preventing electric shock in Commercial Buildings

Effective January 1st, 2019 was the new edition of the AS/NZS 3000 Wiring Rules Standard (Electrical Installations), which outlined over 200 changes and expanded upon the coverage of electrical installations. The changes have taken into account new technologies, new products and improvements in safety, whist clarifying on the previous versions ambiguous requirements.

One of the major changes to the AS/NZS 3000: 2018 is the Residual Current Devices (RCD) requirements for the protection of sub-circuits and relating alterations and repairs (clause

Everyone in the industry is bound by them and every customer is the beneficiary.

In commercial and industrial environments, all 32 Amp outlets and below need to be protected by an RCD. The new AS/NZS 3000 wiring rules require additional RCD protection:

  • 30mA RCDs shall be installed on all final sub-circuits supplying socket outlets and lighting below 32 Amps
  • 30mA RCDs should be installed on all final sub-circuits supplying 32 Amp fixed wired equipment
  • 30mA RCDs shall be installed on all final sub-circuits supplying 32 Amp fixed wired equipment that may classify as an increased risk of electric shock e.g. wet or high risk areas.

The RCD requirements for final sub-circuits has increased to 32 Amp, from the previous 20 Amp to provide personal protection from electric shock to the following circuits:

  • Power circuits for socket outlets (1, 2 & 3 Phase)
  • Lighting circuits
  • Directly connected handheld equipment
  • Directly connected stationary equipment within a high risk area.

All other final sub-circuits not in excess of 32 Amp are to be assessed RCD compatible and if so should be RCD protected to ensure they are both safe and compliant.

The purpose of the clause is to essentially minimise the risk of electric shock. When determining what an increased risk of electric shock is, we take into consideration the electrical equipment or appliance being used (e.g. is the electrical equipment Class 1, exposed conductive parts), external influences (e.g. exposure to elements, vibration, production line) and the connection to the supply.

There are exceptions however, one being applied where the equipment has leakage current that would impair on its reliable operation. This scenario would require a risk assessed appropriate alternative method of installation and equipment selection would be needed to achieve the same level as RCD protection; this could include additional mechanical protection, a separated supply or earth monitoring protection.

Even though the new standard calls for RCDs on all sub-circuits up to and including 32 Amp, exemptions can be applied for when:

  • Sub-circuits supply power to specialised equipment
  • Equipment develops a fault where a greater danger exists than leakage current
  • Equipment operating under normal conditions has the ability to produce earth leakage of a level that will trip a 30 Amp RCD
  • Single items of electrical equipment (e.g. a socket-outlet or light) which is not RCD-protected is replaced with an equivalent item in the same location – like for like
  • Reliability of the equipment is essential to the business operation.

The common complaint of nuisance tripping is not a valid reason for an exemption.

Comply with the Standards, it could save someone’s life, including yours.

What are the requirements for RCDs with alterations or replacement to switchboards?

RCD requirements are applicable when switchboards are altered or replaced. In an alteration, RCDs are required for final sub-circuits. RCDs are also required to protect power-outlets when added to an existing circuit (in accordance with the requirements for new sub-circuits, in the part of the installation in which they are located).

Where power-outlets are being added to an existing circuit and RCD protection is required, the RCD protection is only required to be fitted at the origin of the additional wiring. Where all circuit protection on a switchboard is replaced, additional protection by RCDs are required for the final sub-circuits supplied by that board.

As a Facility Manager, what do these changes mean for you?

The cost of installing new circuits for additional electrical equipment will be substantially higher, with the inclusion of RCDs. Be prepared for an increase in costs for additional circuits (especially 3 Phase), which may lead to the requirements for a switchboard upgrade, in order to facilitate the installation of the RCDs.

As commercial and industrial electrical contractors, it’s important that we are across all of the changes for our clients, awareness and safety are paramount.

Alex Lamblin – Director


For advice and assessment on your commercial and industrial electrical requirements call Prolux on 1800 800 880.

What is 3 Phase Power?

Need more Power? Need to upgrade your power supply to 3 Phase Power?

Need to run industrial machinery, power large motors or heavy loads?

Is your current air conditioning system costing you a fortune to run on single phase?

Does your 3 phase factory require an upgrade, due to an insufficient power supply?

How does 3 Phase Power work?

Electricity is either connected at 230 or 240 volts (single-phase, which accounts for the majority of domestic situations), or 400 and 415 volts (three-phase). A 3 phase system is much more efficient for high-capacity installations. The increase in power efficiency reduces the amount of power distribution equipment (circuit breakers, PDUs, cabling) that must be installed. This then reduces installation and labour costs.

A 3 phase circuit combines three alternating currents of the same frequency, each 120 degrees out of phase with each other. This produces three separate ‘waves’ of power. The power in a 3 phase power supply never drops to zero, but in single-phase the power falls to zero 3 times per cycle. Thus, in a 3 phase power supply, the power is being constantly delivered.

What are the benefits of running 3 Phase Power?

  • Instantaneous power
  • Transmission efficiency – minimum of 2% to 3% more power efficiency of 3 phase over single phase
  • More efficient use of conductors – 3 phase delivers three times the amount of power with three wires instead of two, doubling the usefulness. Over long distances, this is a significant cost saving
  • 3 phase motors run smoothly – power is delivered at a constant rate, with no torque variation or vibration. Reversing can be as simple as interchanging any two phases. The advantage of smoothness also applies to the 3 phase generators as they absorb power
  • 3 phase is easy to generate, easy to transmit, and easy to manipulate in many different ways – 3 phase delivers 1.7 times more amps per whip, reducing number of cables to run
  • 3 phase may be the only distribution option – at very high rack densities: 60 amps+/rack
  • electric motors will be more powerful if using 3 phase power – they will last longer, can be cheaper (no starter required)

What are the disadvantages of running 3 Phase Power?

  • Slightly more complex to design and wire – generally very thick electrical cables are used with 3 phase input cables
  • Must maintain a balanced power consumption across all wire pairs to maintain efficiency – this is mainly applicable to a 3 phase motor operation and less of a problem for a single phase load
  • More current means more risk – 10 kVA per circuit is common. A good idea is to use circuit breakers


Call Prolux Electrical Contractors on 1800 800 880
The Melbourne electrician for all of your power upgrades and 3 phase power electrical requirements.

3/52 Corporate Boulevard, Bayswater VIC 3153