Two parameters are decisive in selecting a residual current device (RCD): threshold (IΔn) And medicine. Additional protection for sockets and personnel is IΔn ≤ 30 mA, and for fire protection it is typically 300 mA. The type is selected according to the type of leakage current produced by the load (AC/A/B).

Additional protection (sockets): IΔn ≤ 30 mA · Fire protection: ~300 mA
Example calculation: Power strip circuit + electronic load (SMPS/LED) → 30 mA (personnel/additional protection) and Type A are recommended.

Selecting a Residual Current Device (RCD)

View the recommended leakage current threshold (IΔn) and relay type according to the intended use and load type.

Leakage current threshold IΔn
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Relay type
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Notes: According to IEC/HD 60364-4-41, for sockets and personnel protection. Additional protection IΔn ≤ 30 mA Recommended; typical 300 mA for fire protection. Type selection depends on the type of leakage current produced by the load: AC (sinusoidal), A (pulsed DC component — electronic), B (straight DC component — inverter), EV charging with Type A + 6 mA DC sensing or Type B. The final choice is determined by the installation conditions.
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How is it calculated?

  1. Select the intended use (power outlet, wet area, fire protection, etc.).
  2. Select the load/circuit type (classic, electronic, inverter, EV charger).
  3. Press Suggest; the threshold and relay type will be displayed.

Frequently Asked Questions

Should I choose 30 mA or 300 mA?
30 mA for sockets and personnel protection (additional protection), typical 300 mA for main fire protection.
What is the difference between Type A and Type AC?
Type AC only detects sinusoidal AC leakage current; Type A also detects electronic loads containing pulsed DC components.
What RCD is needed for an EV charging station?
Due to the risk of straight-line DC leakage, either Type A + 6 mA DC detection or Type B is used.

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This tool and its content are for general informational purposes only; they do not constitute a binding inspection/declaration of conformity. Definitive results will be determined through on-site inspection in accordance with relevant legislation and standards. Get a quote →