Just thinking about EV installs on TT earths where I have a 100mA or 300mA type A RCD protecting a submain, how much DC leakage can be applied before they are blocked.

There is a lot of discussion about EVCP not sharing a 30mA type A rcd with other circuits. But when that RCD/RCBO is then protected by an upstream 100mA or 300mA type A rcd along with other circuits, is it more tolerant to DC leakage current and by how much. Or should we be installing very expensive type B or type F RCD's.

Had a bit of a look around this and from what I case see the 100mA and 300mA devices can only tolerate 6mA DC leakage (Edited). This means that from my thinking at least a type A RCD can not be used to protect a submain or DB supplying an EV and any other circuit. I and I suspect many other electricians haven't been thinking about this.