Type B RCD (diferencial tipo B)

What a type B RCD detects

A type B RCD sees every leak a type A sees (AC and pulsating DC) plus smooth direct current. That kind of leak appears in equipment that rectifies current: EV chargers, solar inverters and variable frequency drives. A DC leak can saturate the core of a type A RCD and leave it unable to trip.

When it is needed

For charging points, ITC-BT-52 asks for a 30 mA RCD of at least class A on each connection point. To cover DC leaks, the technical guide and the standard UNE-EN IEC 62955 recommend two equivalent solutions:

• A type B RCD.
• A type A RCD together with an RDC-DD, the 6 mA DC detector built into almost every quality wallbox.

So type B is the option when the charger has no RDC-DD. It is also used to protect solar and charging installations, alongside specific DC protection.

Type B or type A

Type A detects AC and pulsating DC; type B adds smooth DC. Type B is more expensive, which is why homes usually combine a type A with a charger that has RDC-DD built in.

What to do in your case

If you are adding a charger or solar panels, read the equipment data sheet and see whether it demands a type B or accepts a type A. We check it before quoting in Seville, Spain, so your board complies without paying more than you need.