Type AC
Detects sinusoidal AC residual current only. Adequate for heaters and incandescent lighting; blind to the pulsating DC a rectifier produces. Several countries no longer permit it for general use.
Type A
Sinusoidal AC plus pulsating DC — the fault current from equipment with a single-phase rectifier: computers, LED drivers, washing machines, most appliances. The default for portable RCDs and for the RCD cords we build (RCD cords).
Type F
Type A plus mixed-frequency residual currents from single-phase variable-speed drives (heat pumps, washing machines with inverter motors). IEC 62423.
Type B
Everything above plus smooth DC and high-frequency residual current up to 1 kHz: three-phase drives, photovoltaic inverters, EV charging, medical imaging. The expensive one, and the only correct one on those loads. IEC 62423.
Sensitivity is separate
Any type comes in 10 mA, 30 mA, 100 mA and 300 mA. 30 mA is "additional protection" for people in IEC wiring rules; 10 mA appears in schools, hospitals and wet trades; 100–300 mA is fire protection for a whole installation. A North American Class A GFCI at 4–6 mA is, in these terms, a very sensitive Type A device (GFCI vs RCD).
| Type | Detects | Typical load | Standard |
|---|---|---|---|
| AC | Sinusoidal AC | Resistive heating, incandescent | IEC 61008 / 61009 |
| A | + pulsating DC | Electronics, appliances, LED | IEC 61008 / 61009 |
| F | + mixed frequencies | Single-phase drives | IEC 62423 |
| B | + smooth DC, HF to 1 kHz | Three-phase drives, PV, EV charging | IEC 62423 |