TT Supply for EVCs

Also should each of the D/Boards have a time delay S-Type RCD acting as a Main Switch or will a standard 4 pole dissconnector suffice as a Main Switch? 

How are you providing protection against electric shock prior to the outgoing RCBOs? Is your switchfuse/isolator, bus-bar chamber and DB (prior to the RCBOs) constructed to provide double or reinforced insulation? (most of the ones I've seen of that kind of size tend to be steel cased, which makes me suspect not). If not you'll presumably want some means of ADS - which presumably means an RCD of some kind at the point you transition from double/reinforced insulation to earthing. If the transition point is within the DBs (i.e. it's double insulation all the way up to and including the DB incomer and ADS within the DB and onward) then an RCCB incomer would make sense, but quite possibly you'd need something upstream of that.

 

Am I correct assuming the RCBOs must all be 4 pole because the Neutral is classed as a line conductor?

Depends on the reason for having the RCBOs - if it's to provide additional protection to the socket/EV (as per 722.531.2.1.1) - usually because there's no RCD at the charge point - then yes it needs to disconnect all live conductors, including N. If however it's just there to provide TT-style ADS for the final circuit up to the charge point (where another RCD protects the EV) then I'd say normal rules apply and only the line conductors need be disconnected.

 

protected by 30mA Type A RCBOs mounted in each of the D/Boards.

Is there an assumption there that the charge points will have some built-in protection against d.c. residual currents over 6mA - if not you might need type-B RCDs (or similar - e.g. some manufacturers offer EV types).


BTW - keep an eye on protective conductor currents, RCD ratings and the reliable maximum electrode resistance needed to keep within the 50V requirement.


   - Andy.

Also should each of the D/Boards have a time delay S-Type RCD acting as a Main Switch or will a standard 4 pole dissconnector suffice as a Main Switch? 

How are you providing protection against electric shock prior to the outgoing RCBOs? Is your switchfuse/isolator, bus-bar chamber and DB (prior to the RCBOs) constructed to provide double or reinforced insulation? (most of the ones I've seen of that kind of size tend to be steel cased, which makes me suspect not). If not you'll presumably want some means of ADS - which presumably means an RCD of some kind at the point you transition from double/reinforced insulation to earthing. If the transition point is within the DBs (i.e. it's double insulation all the way up to and including the DB incomer and ADS within the DB and onward) then an RCCB incomer would make sense, but quite possibly you'd need something upstream of that.

 

Am I correct assuming the RCBOs must all be 4 pole because the Neutral is classed as a line conductor?

Depends on the reason for having the RCBOs - if it's to provide additional protection to the socket/EV (as per 722.531.2.1.1) - usually because there's no RCD at the charge point - then yes it needs to disconnect all live conductors, including N. If however it's just there to provide TT-style ADS for the final circuit up to the charge point (where another RCD protects the EV) then I'd say normal rules apply and only the line conductors need be disconnected.

 

protected by 30mA Type A RCBOs mounted in each of the D/Boards.

Is there an assumption there that the charge points will have some built-in protection against d.c. residual currents over 6mA - if not you might need type-B RCDs (or similar - e.g. some manufacturers offer EV types).


BTW - keep an eye on protective conductor currents, RCD ratings and the reliable maximum electrode resistance needed to keep within the 50V requirement.


   - Andy.