Regulation stating a type AC RCD can not be upstream from a type A RCD

Possibly Andy, but corrections are possible, although they can cause red faces! However I think it is important that the situation is fully understood by the industry, and the reasons need to be correct. We do tend to have a situation where IEC (or Cenelec or whatever) has suggested a regulation, but it is important to know exactly why and to be able to explain to customers why the item they bought last year is no longer satisfactory. If the reasons were as seems to be suggested, I think type As would not be suitable either as the alleged DC leakage current is in no way controlled, except by a potential fault resistance (its DC)!

Agreed the charger circuit does not need the protection as the charger has a built in RCD. But the RCD is also protecting other circuits and it will still be blinded by DC leakage from the charger.

IEC 62350 referenced in note 2  is probably documents the guidance on cascading RCD's but unfortunately I don't have access, I suspect this is the case for most electricians.

Alan B said:

IEC 62350 referenced in note 2  is probably documents the guidance on cascading RCD's but unfortunately I don't have access, I suspect this is the case for most electricians.

Not in terms of whether a Type AC can be used upstream of a Type A or Type B, or whether a Type A can be used upstream of a Type B.

Whilst Type B are mentioned, note that this Technical Report (it's not a full IEC standard) was published before Type B and Type F RCDs fully appeared in the product standards (BS EN 62423), and so Type B's only get a cursory glancing mention, and Type F's are not mentioned at all.

Except that bridge rectifier has a smoothing capacitor on the output, so the DC has a rather indeterminate ripple, so may need a B type to be detected in all cases, the 100% unsmoothed (no capacitor) case is all that a type A is certain to trip on - though it may trip of course, and probably will so long as the DC is not too smooth, the problem is it is far from clear what that is.

One of the things I have muttered about many times over the years is that the British can’t just go with a light touch when adopting new ideas and methods of working.

I know I have previously posted links to the Legrand French website as well as others showing installation methods in Mainland Europe.

In Mainland Europe Type AC RCDs are considered quite acceptable upfront of many circuits including socket and lighting circuits, the requirement is to have at least one Type A for circuits supplying equipment such as EVSE, washing machines and cooking hobs which have known problems with DC leakage.

But the Brits being the Brits have to go for complete protection by Type A RCDs for all circuits.

Don’t go blaming our European cousins for an apparent total ban on Type AC RCDs for socket and lighting circuits, because they do still use them.

www.legrand.fr/.../que-doit-on-brancher-sur-un-interrupteur-differentiel-de-type-a

Thanks, one I had missed,  so with that in mind, to recover double fault to danger protection then  for the lead out to the car, we need to insulate and sheath the CPC to the same standard as if it was  another  live core.

Is that not already the case ?

Mike.

CYA syndrome or perhaps to "monetarise the situation" David ? 

The Energy related Products regulations 2009 (a plain language explanation here) do not absolve a company from meeting all the other ones, like the Low Voltage directive, EMC directives and so on, and as such certainly do not oblige you to have any earth leakage either AC or DC.
Indeed I recognize the 3.5mA figure as familiar from the AC RMS earth leakage upper absolute limit if you wish to sell something with a plug on it for general use . (and so a fail limit setting for some PAT equipment).

The type A or B RCD is nothing to do with the ErP regs, but everything to do with the pump internals, and the credible failure modes about which they seem to know very little.  I'm sure you can use a type A RCD with it, and probably an AC type as well but who knows, clearly not the folk who sell it.

I presume they never came back with a figure for DC leakage?

Mike.

A DC component is a component within the appliance that may cause DC leakage into the AC circuit supplying it, it’s where the appliance converts the AC supply to DC via a transformer and rectifier. Examples of things that include DC components are basically anything with a PCB so washing machines, chargers, also EV chargers, TV, everything digital. Really we should have been using A type RCDs as standard ages ago because all these pesky dc currents build up the more digital tech you add to the installation. The big brown book has basically relegated AC RCDs unless you can be certain of no DC components are connected to the circuit it protects. It’s on page 157 of the big brown book. 53.1.3.3 NOTE3 “RCD type AC shall only be used to serve fixed equipment, where it is known that the load current contains no DC components”  so maybe an old fridge with a dedicated circuit.

Does it have a PCB? Does it run on rectified power (this might include LED lightbulbs)? Are you unsure if the previous two answers are yes? If the answer to any of those three questions are yes then you should not use an AC RCD.