Tail sizes from PV sub-board

[Wilko]

I wouldnt say it’s the best way if there is spare way on a RCD protected way that shares the same side as a socket circuit for example. It would actually be non compliant due to how long the inverter takes to shut down which can be up to 5 seconds under G83.

Learning every day.
If I've understood correctly - in a dual RCD board if they've attached PV invertor to MCB under one of the RCDs, if that RCD detects a fault and trips, great. But the invertor continues to put 230V onto the common MCB busbar. So ADS has not been achieved (!!!).

 

[davesparks]

Where does it state this would be non compliant, not had much to do with these systems so would be interested.

I can’t give a regulation, but plain old common sense should be enough.
If a person receives a shock the RCD will trip, but the PV will continue to supply power to all circuits supplied by that RCD for a period of time, therefore defeating the purpose of the RCD and killing the person.

 

[westward10]

I can see the sense of it now I just wondered if this is quoted anywhere.

 

[Ian1981]

Regulation 712.411.3.2.1.1 states that on the ac side the pv cable shall be connected to the supply side of a OCPD for automatic disconnection of circuits supplying current carrying equipment

 

[SibertSolar]

Nuisance tripping "might" be a problem when sharing an RCD, but that's the least of the potential issues. More likely (when using transformerless inverters) is that the Type-AC RCD (usually fitted in residential CUs) might become saturated and never trip under fault conditions. That's in addition to the scenario outlined by others relating to the shutdown times of PV inverters and ADS intention of the primary RCD in the first place.....amazing that this topic still causes discussion so many years down the line!! As for the OP's original question, using 10mm2 tails from henley blocks broken into the meter tails (25mm2) is perfectly fine so long as the OCPD on the PV connection is suitably rated. In fact, I'd go so far as to say this is a better method that using a spare way on the non-RCD protected side of the main CU (various reasons including ease of monitoring and avoiding potential issues with RCDs....)

Just my tuppence...