Type A RCD (diferencial tipo A)

What a type A RCD detects

RCDs (diferenciales) are classified by the kind of leak they can see:

• Type AC: only sinusoidal AC leaks. The classic device in older Spanish installations.
• Type A: AC leaks plus pulsating DC, which appears in appliances with electronics such as modern washing machines, induction hobs or variable speed drives.
• Type B: all of the above plus smooth DC leaks.

With so much electronics at home, a type A RCD is now the sensible choice over type AC.

Why your EV charger needs one

ITC-BT-52, section 6.1, requires every charging point to be protected by its own 30 mA RCD of at least class A. The text does not literally demand 6 mA DC detection, but the technical guide, the standard UNE-EN IEC 62955 and manufacturers recommend it: a fault in the car’s onboard charger can inject DC that blinds a type A device.

Type A plus RDC-DD, or type B

• Type A with RDC-DD: the charger has a built-in 6 mA DC detector. Almost every quality wallbox includes it, and it is the cheaper route.
• Type B: the RCD detects DC by itself. Used when the charger has no RDC-DD.

What to check before buying

Check whether the charger has RDC-DD: it decides which RCD goes in your fuse box (consumer unit; breaker panel in the US). We check it when fitting a home EV charger for a house in Seville, Spain, together with the rest of your electrical safety devices.