Hi Andy

All understood but where is it documented in BS7671 or the on site guide?

I`ll vote for it being OK because you`ve cascaded both types so if the AC type is actually a problem (Jury out on that one perhaps) then it still has type A which should work (if both are DP switching) . If the AC one is , in reality, not really much of a problem then you might have mitigated failure risk to some degree too.

But the type A RCD is also protecting other circuits, including a socket circuit  which could still have no RCD protection. Sorry I missed this in the original post, will update.

531.3.3 "....RCD Type AC shall only be used to serve fixed equipment, where it is known that the load current contains no DC components."

No DC components, not just up to 6mA.

so can't be used on (new or altered) socket circuits.

Edit; together with 132.16 Additions and alterations " ... condition of any existing equipment...will be adequate for the altered circumstances."

Hi Guys, Im new to the Forum but I hope this information can help Which I found earlier. 

Selectivity of RCD types - Wiring and the Regulations BS 7671 - IET EngX - IET EngX (theiet.org)

Also Look at regulation 722.531.3.101

Also Regulation 314.1 is all about selectivity and Poor discrimination this is the only regulation I think that applies to your question. 

If the downstream device and upstream are both rated at 30ma then in my opinion can cause an issue. 

If there is AC leakage in the type A or AC then one or the other or both can trip. Either by Fault of Nuisance tripping. 

if the Unit is supplied by SWA and the Zs is within permitted Values for an MCB device then RCD protection is not needed on that circuit but the Devices inside the Charger will have to be a Type A RCD and a RDC-DD and will have to disconnect all live conductors and disconnect power from the outlet. 

All of the above is just my opinion and interpretation 

What does everyone else think ? 

Yassir

Agreed. Its supplied on an SWA cable. The best solution would be to use a non RCD protected feed from the DB, but that would mean a significant re organisation of the DB or an additional DB. This was installed by another company, I am recommending the customer goes back to the original installer and asks them to replace the RCD. This is going to cause enough problems, trying to force them to correct the selectivity issue as well is going to cause a big fight.

I have informed the customer that ideally the charger should be on it's own non RCD protected output from the DB or additional DB but it would be ok to just replace the type AC RCD with a type AC. 

If it a high integrity DB then insert a MCB next to the main switch if possible, The customer could request that I guess 

I am pretty sure on an NICEIC webinar i watched the other day they stated that all EV charge points should have a dedicated RCD. I took that to include the supply circuit if it needed one but could be wrong.  

Gary

I’m struggling to understand the relevance of the regs quoted in NAPIT Codebreakers.

I’m struggling to understand the relevance of the regs quoted in NAPIT Codebreakers.

I agree 411.3.2.1 makes no sense if it's about additional protection, and if they're going to refer to 411.3.3 it probably should include 411.3.4 as well (unless that's done separately with a lower code). C2 seems a bit steep for internal sockets in many cases anyway.

   - Andy.