AC Type RCD No PV or Car Charger C3 or C2

AJJewsbury said:

I think it's certainly more nuanced - surely it'll take a significant amount of d.c. residual current to blind even the simplest of AC type RCD - I would have thought d.c. a mA or two would at worst de-sensitize it a bit (e.g. maybe tripping at 29mA instead of 27mA - but still within spec) - with increasing d.c. residual currents of course there comes a point where it becomes a problem. The question is how likely is it that a typical domestic will produce enough d.c. residual current to be a problem? Even A types aren't a complete panacea to this issue - they're only good up to 6mA d.c. - after that their performance is as undefined as AC types.

I suspect you are probably correct but unless someone actually publishes data on what the real performance is or gives more specific guidance it's very difficult as an electrician to make an informed engineering decision other than in most cases a type AC RCD in a domestic install is a C2, especially as a NAPIT member where the organisation has published a document that states it's a C2. Even if we had a DC leakage meter, given the different types of DC leakage the challenges with creating a worst case scenario the measurement results will be difficult to interpret at best. Then we have no idea on what our limit is, according to the standard presumably 0 DC leakage.

It's the same or maybe worse than deciding if its ok to install a third party MCB in to a consumer unit, at least with the consumer unit you can check that the bus bar slots are lined up and won't put stress on the connections.

Is there any published data on the typical amount of DC leakage in a domestic installation?

Alan B said:

a type AC RCD in a domestic install is a C2, especially as a NAPIT member

That is a step too far for me. That would make a lot of rented accommodation unlawful.

It all depends on which leg you hope to stand on when something goes skew-whiff...

It all depends on which leg you hope to stand on when something goes skew-whiff...