Is MCB type B + RCD type B ok to have in electrical cabinet?

In case of MCBs, the letter designation is a definition of a trip curve. For charging of EV's it was decided that the C curve is best to use in general. Usually we recommend the use of MCB with curve C. It is more immune to the starting current of motors, etc ...

This curve is used where a moderate inductive component of current is present.

Also the curve D could be suitable at the location where there is a very high inductive component of current present.

MCB with curve B is safe to use, however it could happen that it would be tripping unnecessarily.


Can we connect INCH with build in RCD type A + 6 mA DC sensor to electrical cabinet with MCB type B + RCD type B ?

The requirement is that each charging point must be protected with RCD. The RCD Type B should be used, or as an alternative, a combination of RCD Type A and 6 mA DC sensor.

When the charger has only one charging point (one socket), it can be protected with the RCD inside the electrical cabinet. And when the charger is equipped with two sockets, the proper RCD's must be installed inside the charger (it is not allowed to protect both charging points with one RCD).

Overall, the described situation is safe to use and it even has redundancy in the safety components, which is even safer.

The only thing that is not optimal, is the MCB of type B. In case of unnecessary tripping, this device should be replaced with MCB of type C (or D, if the specifics of the location need it).