Understand the different types of RCDs available and their various uses as well as the minimum type required by each Standard. In some cases, the electrical contractor will need to select the type of RCD. The table below provides some guidance regarding the various types of RCDs and their uses – the further down the table more refined protection is provided. Certain types have specific uses and are manufacturers variations of the types mentioned in the Wiring Rules.

Download ERAC guidance on RCDs

Electrical equipment

It is likely that advice is provided in the installation instructions where a specific type of RCD be required. If this is not the case, it may require consultation with the equipment supplier/manufacturer to select the correct type of RCD. The table below provides some guidance.

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Medical installations

For medical installations with body-protected or cardiac areas it is a requirement to install Leakage Protective Devices which could be in the form of a Type I (10mA) RCD.

It should be noted that a Type I (10mA) RCD is very different to a Type A (10mA) RCD, with the variations being the manufacturing standard, rated tripping time (40ms vs 300ms) and their intended use (medical or general use).

Electrical installations

It is possible to use Type S RCDs to provide some additional protection against the initiation of fire. They are also used extensively in mining and quarrying operations.

Considerations:

1. Manufacturer’s instructions
2. Supplier and/or manufacturer’s savice
3. Type of electrical equipment
4. Type of electrical installation (e.g. medical)
5. Protection required (e.g. initiation of fire, electric shock)
6. Waveform of the fault current to earth
7. Types of RCDs available

RCD Type

30mA – Residual Current Devices
Type	Symbol	Current	Time	Use	Tripping Ensured FOR
AC		30mA	300ms	General use – Cannot be used in NZ, Not recommended	Residual sinusoidal alternating currents
A		30mA	300ms	General use, Minimum recommended, Minimum Requirement in AS/NZS 3001, AS/NZS 3002, ..	ALL Type AC features PLUS Residual pulsating direct currents
A-SI  or A-APR	SI or APR * manufacturer variation	30mA	300ms	General use, low temperatures, high immunity to unwanted tripping	ALL Type A features PLUS High or super immunity to unwanted tripping
F		30mA	300ms	Variable speed drives, electronic ballasts	ALL Type A features PLUS Composite residual currents PLUS Residual pulsating direct currents superimposed on smooth direct current
B		30mA	300ms	3 Phase rectifying circuits, variable speed drives, PV inverters, electric vehicle charging stations, specialist medical equipment	ALL Type F features PLUS Residual sinusoidal alternating currents up to 1000 Hz PLUS Residual pulsating direct currents superimposed on smooth direct current of 0.4 times the rated residual current
B+	* manufacturer variation	30mA	300ms	As above where high frequency transients are generated	ALL Type B features PLUS Residual sinusoidal alternating currents up to 20 kHz

Non 30mA – Residual Current Devices
Type	Symbol	Current	Time	Use	Tripping ensured FOR
A		10mA	300ms	General use, not for patient areas (medical), educational institutions (NZ), childcare facilities (NZ)	Residual sinusoidal alternating currents AND Residual pulsating direct currents
I	AS/NZS 3190, AS/NZS 61008.1 or AS/NZS 61009.1	10mA	40ms	Not general use, leakage protection device (LPD), medical, body protected areas, cardiac areas, home care medical	Residual sinusoidal alternating currents AND Residual pulsating direct currents AND Composite residual currents AND High or super immunity to unwanted tripping
S		Selective, 100mA -300mA	Selective, Time delayed	Mining and quarry operations, generators, caravan park site supplies, protection against the initiation of fire	Residual sinusoidal alternating currents AND Residual pulsating direct currents

References:

• The Wiring Rules (AS/NZS 3000)
  • 4.102 – Residual current device (RCD)
  • 4.112 – Socket residual current device (SRCD)
  • 6.2.2 – Types of RCD
  • 6.2.3 – Protection against initiation of fire
  • 6.3.2.4 – Home care installations—Australia only
  • 12.5.2.2 – Overcurrent Protection for Electricity Converters (E.g. Inverter or UPS)
  • 3.5.2.2 – Overcurrent Protection for Electricity Generation Systems (E.g. PV Array & Inverter or Engine Driven Generator)
• AS/NZS 4777.1
  • 4.4 – RCD’s on Multiple Mode Inverter System Final Sub-circuits
• AS/NZS 3002
  • 2.4 – Residual Current Devices Type for Generator Sets and Switchboards
• AS/NZS 3003
  • 5.14 – Leakage Protective Device (LPD)
  • 8 – Residual Current Devices (RCDs)