On a TT install, where the supply for EV chargers comes from a feeder pillar. If the EV charger has a 30mA Type B RCD, is there a requirement for an upstream 300mA Type B RCD or can it be a different type?
Can I specify 300mA RCDs as the main switch (is this type B?), and what would the solution be if I wanted a 250A incomer, would I then need an additional upstream type B RCD for each charger between the distribution board and the charging unit. This is a very expensive component if needed.
Siemens and an article from Voltimum have indicated that the upstream RCD needs to Type B and the code of practice shows a 300mA RCD upstream on a diagram but not which type.
Looking for some guidance on this and an explanation if possible.
Thanks
