I'm with Zoomup. Your work has to be compliant as far as it can be. I would even say that it may be acceptable to add a circuit with no RCD protection at all. Let's not forget that BS 7671 is not mandatory. IMHO, "it's all I can afford" is a good reason for doing the best that you can under the circumstances.

What will come next? No new socket circuits unless they have AFDD protection?

What's all this about blinding? Surely the problem with a type AC RCD is that it may not trip with a pulsed DC fault.

I'm with Zoomup. Your work has to be compliant as far as it can be. I would even say that it may be acceptable to add a circuit with no RCD protection at all. Let's not forget that BS 7671 is not mandatory. IMHO, "it's all I can afford" is a good reason for doing the best that you can under the circumstances.

What will come next? No new socket circuits unless they have AFDD protection?

What's all this about blinding? Surely the problem with a type AC RCD is that it may not trip with a pulsed DC fault.

Well the question was whether the new work would be compliant [ i.e. with BS 7671 amd2 ]. The answer is no. There are separate questions as to whether the work legally or morally should be complaint.

If installing a new socket in e.g. a HMO, then yes, that circuit now needs to be AFDD protected - in the same way that new sockets on an existing circuits need to be RCD protected one way or another.

I'm happy to defer to others about the whole blinding thing, but my understanding was that the sensitivity of type ACs could be reduced / eliminated by small DC currents.

Chris Pearson said:

Let's not forget that BS 7671 is not mandatory.

Not the case if you have Solar PV or other form of generation that operates in parallel with the DNO network, although this will kick off the rabbit hole of "which version of BS 7671, because the legislation says ..." even though this has been run many times before.

Still, it's true to say that, at least right this minute, there's no need to use BS 7671:2018+A2:2022 (but you can if you want).

Morning Chris P and everyone else.

You are wrong when you say BS 7671 is not mandatory.

APD P requires all installations to comply with BS 7671 in dwellings and common areas of blocks of dwellings. Some of the installation work may be notifiable but all work has to comply;y with BS 7671.

At the moment APD P has not been updated to the 18th Edition but I am reliably informed it will be soon.

In any case if you are a professional, qualified and competent electrician you will be designing the installation to BS 7671, installing the installation to BS 7671 and testing the installation for compliance with BS 7671.

Only your new part has to fully comply with BS 7671 but you should make comments on the existing installation condition in the box provided for that purpose. In my experience there should always be comments there.

Sorry John,

I would  not normally bother but this is an important point and an error that is often made.

It is not as simple as you suggest. The approved docs are not themselves the actual law, just an example of one (strongly recommended ) way of meeting the law .

The law itself is actually  the various building control regulations, the building act, and the act does not mention BS7671 at all. and then a stack of  statutory instruments that modify these acts there are many of those  several per year, mostly unread by most MPs and not voted on.

- but as far as the approved docs are concerned, you can do other things and break no law, so long as  you can convince a building control officer are they are  equivalent in meeting the letter of the various acts.

Some of us have and no doubt will do so again. I have an intumescent cat flap into my garage for example, and some German standard wiring in my downstairs shower room, and all the completion certs to show it is legal.

Indeed load the latest part P approved document here and turn to page 3 of 22 in the PDF reader, and the section 'What is an approved document'

where in among the rest is the key

Note that there may be other ways to comply with the requirements – there is no obligation to adopt any particular solution contained in an approved document. If you prefer to meet a relevant requirement in some other way than described in an approved document, you should discuss this with the relevant building control body

Page 10 of 22 (page 3 of the actual document) highlights the only bit that is the actual legal requirement.

Now at any time the primary legislation may change, or indeed another SI may go before parliament, but for now, BS7671 is not called up in the legislation, only in the guidance to it.

 Regards Mike.