What type of RCD do I need for my EV charger?
This article introduces how to select the right type of RCD installed outside the home EV chargers. Although EV chargers might be declared as type-A 30 mA RCD and RDC-DD, we strongly suggest to install a type-A 30 mA RCD in a water-proof distribution board next to the EV charger, in order to ensure the safety of every charging circle.
Nobody wants to be injured or electrocuted during electrical vehicle (EV) charging. EV users probably know that Residual Current Devices (RCDs) is the last line of defense that protects people from electrical shock. However, most of EV users don’t know if the RCD installed out of their EV charger can provide sufficient electrical protection. For non-professional users, this blog post introduces how to select the right type of RCD installed outside the EV chargers at home. 


Step 1: Get to know the IEC/EN standard request about residual current protection

The standards of IEC/EN 61851-1: 2017 and IEC 60364-7-222:2018 specify the protective measures for mode-3 EV charging system (a wall mounted AC charging box installed at is usually a mode-3 EV charger) as followings
  • Option 1: RCD Type B  (IEC 60947-2 type-B mRCD/CBR or IEC 62423 type-B RCCB)
  • Option 2: RCD Type A (IEC 61008-1 type-A RCCB, IEC 61009-1 type-A RCBO or IEC 60947-2 type-A mRCD / CBR ) and RDC-DD (IEC62955 RDC-PD or RDC-MD)

Step 2: Check the type of residual current protection integrated within the EV charger

In the datasheet of your EV charger, one of the following type of integrated residual current protection is often declared 
  • Type-A 30mA RCD (IEC 61008-1 / IEC 61009-1 / IEC 60947-2) 
  • Type-A 30mA RCD(IEC 61008-1 / IEC 61009-1 / IEC 60947-2) + RDC-PD (IEC 62955)
  • RDC-MD (IEC 62955)
  • Type-B RCD (IEC 62423 / IEC 60947-2)
Some EV charger manufacturers might declare only AC 30 mA & DC 6 mA compliancy without mentioning the RCD & RDC-DD standard. In this case, please contact the EV Charger manufacturer for further clarification. In the worst scenario of no clarification received from the manufacturer, please consider installing type-EV RCD (an integrated type-A RCD and RDC-DD) or type-B RCD outside your EV charger.

Step 3: Select the right RCD for installation outside EV chargers accordingly

After getting to know the EV charger manufacturer declaration of integrated residual current protection, you can use the following table to help with your RCD selection.

Manufacturer Declaration of integrated RCD type at EV charger
External RCD installation meeting standard request
External RCD installation recommended by our experts
Type-A 30mA RCD (IEC 61008-1 / IEC 61009-1 / IEC 60947-2)
Type-B RCD (IEC 62423 / IEC 60947-2) or RDC-DD (IEC 62955) Type-B RCD (IEC 62423 / IEC 60947-2) or Type-EV RCD  (IEC 61008-1 / IEC 61009-1 + IEC 62955)
Type-A 30mA RCD(IEC 61008-1 / IEC 61009-1 / IEC 60947-2) + RDC-DD (IEC 62955)
Not needed in theory Type-A 30mA RCD (IEC 61008-1 / IEC 61009-1 )
RDC-DD (IEC 62955)
Type-A 30mA RCD (IEC 61008-1 / IEC 61009-1 )
Type-A 30mA RCD (IEC 61008-1 / IEC 61009-1 )
Type-B RCD (IEC 62423 / IEC 60947-2)
Not needed in theory
Type-A 30mA RCD (IEC 61008-1 / IEC 61009-1 )

Our experts do suggest to install a type-A 30mA RCD outside your EV charger - even if your EV charger alone declares integrated residual current protection meeting the request of IEC61851-1: 2017 and IEC60364-7-222:2018. It is much more difficult to ensure every EV charger in fully compliance with Type-A RCD standards of IEC 61008-1, IEC 61009-1 or IEC 60947-2 than in fully compliance with RDC-DD standard of IEC 62955. As far as we know, some blue-chip type-A RCD manufacturers still maintain budget of compensation in the occur of non-tripping accident after manufacturing type-A RCDs over twenty years. Thus, it is worth spending only 20~30 EUR in having an reliable type-A 30 mA RCD installed outside your EV charger, which makes the integrated type-A 30 mA protection at the EV charger act like a back-up protection device.

Step 4: Install the selected RCD outside your EV charger

Now with the right RCD selected, please order it and contact an electrician for installation. In some countries, only qualified electrician are allowed to install RCDs, and please check with your local regulations and laws.


*Special note:
(1) If the above step 1, 2 and step 3 are too complicated to be followed, you might try the simplest approach – select a 
type-EV RCD (An integrated Type-A 30mA RCD and RDC-DD). As illustrated by our another blog post, we think it is easier to install a type-EV RCDs than a type-B RCD at home charging application.
(2)Most of countries in Europe, Asia and Africa use IEC standards. 





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