I wondered how the absence of AFDDs jumped to code 3 status in Best Practice Guide 4 issue 6 as the same issue only warranted an observation “worthy of note” in BPG 4 issue 5. Further investigation revealed a subtle change between the two issues in the use of the codes.

In BPG 4 issue 5, a code 3 should be used where a recommendation would result in a significant enhancement of the safety of the installation whereas in the more recent BPG 4 issue 6, a code 3 should be used where a recommendation would result in an enhancement of the safety of the installation.

Note the dropping of that all-important word “significant”.

This opens the gate for any recommendation, no matter how minor, to be considered an improvement.

So according to BPG 4 issue 6, where AFDDS are absent in locations such as the one mentioned by me in the OP, a code 3 should be given, as Graham correctly indicated (thank you for pointing this out).

Now whilst I think that I could use my knowledge and experience of fire safety to argue that the provision of AFDDs in this particular building would not bring significant enhancement to the safety of the installation, the case would be weak to contend that AFDDs would bring no enhancement at all.

Looking at the contributors to the compilation of Best Practice Guide 4 issue 6, I note many of the great and the good of our industry, including the IET. I assume, therefore that the re-worked wording of the concept of a code 3 comes with the blessing of the IET.

I have never been a slave to the plethora of guidance that emanates from other self-appointed doyens of the industry, but I have always done my best to stick as close as possible to that which originates from the IET, a body for which I have the utmost respect.  

Whilst I would whole heartedly agree with Grahams view that following guidance is not competence, I do feel that this Best Practice Guide diminishes the need for it.

I have an old suitcase in the loft which is full of dusty old electrical books from my college days, just the place to park the remnants of any engineering judgement I may once have had.   

lyledunn said:

In BPG 4 issue 5, a code 3 should be used where a recommendation would result in a significant enhancement of the safety of the installation whereas in the more recent BPG 4 issue 6, a code 3 should be used where a recommendation would result in an enhancement of the safety of the installation.

Neither of those definitions are given, nor used, in BS 7671.

In context, BPG4 is guidance on informative (guidance) text in BS 7671. However, I would agree that, in this particular context, we are talking abut the 4th dashed indent to Regulation 653.2. I think in this context, we are looking at the C3 being a non-conformity to a normative requirement

lyledunn said:

Whilst I would whole heartedly agree with Grahams view that following guidance is not competence, I do feel that this Best Practice Guide diminishes the need for it.

Perhaps ... then again perhaps not.

For example, it perhaps would not be correct to give a C3 to no AFDD on a socket-outlet circuit rated up to 32 A in an installation that is not in the four bullets in Regulation 421.1.7, as its installation is a recommendation not a [normative] requirement?

lyledunn said:

In BPG 4 issue 5, a code 3 should be used where a recommendation would result in a significant enhancement of the safety of the installation whereas in the more recent BPG 4 issue 6, a code 3 should be used where a recommendation would result in an enhancement of the safety of the installation.

Neither of those definitions are given, nor used, in BS 7671.

In context, BPG4 is guidance on informative (guidance) text in BS 7671. However, I would agree that, in this particular context, we are talking abut the 4th dashed indent to Regulation 653.2. I think in this context, we are looking at the C3 being a non-conformity to a normative requirement

lyledunn said:

Whilst I would whole heartedly agree with Grahams view that following guidance is not competence, I do feel that this Best Practice Guide diminishes the need for it.

Perhaps ... then again perhaps not.

For example, it perhaps would not be correct to give a C3 to no AFDD on a socket-outlet circuit rated up to 32 A in an installation that is not in the four bullets in Regulation 421.1.7, as its installation is a recommendation not a [normative] requirement?

Perhaps the old code 4 should be brought back. I note that the said BPG uses an observation "worthy of note" which to me implies that there is no suitable code available. It begs the question why deviate from the exemplar form set out in Appendix 6. 

Not that I would hold the codes used in the periodic verification forms used in ROI up as any kind of shining example, they do at least let me avoid making a recommendation for improvement just because a normative aspect is absent. (IS1010-1 2020 used in the ROI  sensibly makes only a recommendation that AFDDS should be used where the fire risk is other than standard).