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.

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.