RCD Selection Guide
AS/NZS 3000:2018 (Australian & New Zealand)
Inputs
Results
Recommended RCD Type
AC
30 mA
2P RCD @ 20 A
Sensitivity adequate for location
30 mA (<= 100)
RCD type adequate for load
1 (>= 1)
Disconnection time
300 ms (<= 300)
RCD rating ≥ circuit current
20 A (<= 20)
Recommended Products (Informational)
AC-type 30mA RCD (e.g., Clipsal, Schneider Electric, Legrand, Eaton)
DRAFT: Pending CPEng review for compliance accuracy
RCD Selection Guide — AS/NZS 3000:2018
Residual Current Devices (RCDs) provide life-saving protection against electric shock from direct contact, indirect contact, and earth leakage faults. This guide helps you select the correct RCD type, sensitivity, and rating for any circuit.
RCD Types & Applications
- Type AC: Standard RCDs for pure AC loads (lighting, motors, general circuits). Cannot detect DC fault current.
- Type A: Detects controlled DC fault current (smooth DC from rectifiers). Required for socket outlets in New Zealand, EV chargers, VFDs with controlled DC.
- Type F (B with filters): Detects AC and DC faults; filters out harmonics and transients. Suitable for soft starters, adjustable speed drives with low harmonics.
- Type B (Bi-directional): Detects AC and DC faults, including high-frequency transients. Required for medical locations, high-harmonic loads, and complex electrical systems.
Sensitivity Levels & Location
- 10 mA: Extra protection for high-risk locations (socket outlets in bathrooms, wet areas). Very sensitive; detect low leakage.
- 30 mA: Standard socket outlet protection; wet areas and pools. Balance between sensitivity and nuisance trips (AS/NZS 3000 Clause 2.6.4)
- 100 mA: Fixed appliances and lighting in dry indoor locations. Acceptable for lower-hazard circuits (Clause 2.6.4)
- 300 mA: Selective main RCDs upstream of sub-circuit RCDs. Reduces nuisance tripping on circuits with harmonic loads.
Special Considerations
- Variable Speed Drives (VSD): Require Type A (minimum) or Type B RCDs due to controlled DC fault current
- Non-linear loads (harmonics): May cause nuisance tripping on Type AC; Type B preferred
- New Zealand mandate: Type A required for socket outlet circuits from Amendment 1 of AS/NZS 3000:2018
- Three-phase installations: Requires 4-pole RCD (L1 + L2 + L3 + N)
- Disconnection time: >100 ms for wet areas, >200 ms for outdoor, >300 ms for indoor dry (Clause 2.6.2)
Disclaimer: These recommendations are indicative only. RCD selection must be verified by a qualified electrical engineer in accordance with AS/NZS 3000:2018 and site-specific electrical design. Consult manufacturer datasheets for product specifications and breaking capacity ratings. This guide does not replace professional electrical design.