RDC-DD (residual direct current detecting device)

What an RDC-DD is

The RDC-DD (residual direct current detecting device) is a 6 mA DC leakage detector. It is almost always inside the charger itself and is covered by standard UNE-EN IEC 62955. If it detects a direct current leak, it stops the charge.

Why it is needed

The car has an onboard charger that converts AC into DC for the battery. If that unit fails, a DC leak can appear. The problem is that a DC leak of a certain size can “blind” a type A RCD, which would then fail to trip on a dangerous leak.

ITC-BT-52 requires a 30 mA RCD of at least class A on each charging point. The technical guide, standard UNE-EN IEC 62955 and manufacturers also recommend 6 mA DC detection. There are two ways to comply:

• Type A RCD plus RDC-DD built into the wallbox. The usual solution.
• Type B RCD, which detects DC by itself but costs much more.

Which wallboxes have it

Almost all quality chargers include it. To check, look for “RDC-DD”, “6 mA DC detection” or “IEC 62955” on the data sheet. If your unit lacks it, a type B RCD has to go in the board. That can change the quote considerably, so check before buying the charger.

Who decides

Choosing the right protection is part of the registered installer’s job and is recorded on the boletín. We review your charger’s data sheet and propose the right protection. See home EV charger for a house and EV charger brands in Seville, Spain.