I mentioned unknown unknowns because a DIYer being able to solder some joints doesn't make them competent in repairing gas pipework. They simply don't know what else is required. You then made the stupid statement that someone trained in fitting gas cookers isn't competent because they don't know things like metallurgy. Crazy nonsense.
Only crazy if you can't see the point I was making, but then I suspect that if you haven't by now, you never will. I'll try spelling it out for you ...
You pick upa piece of copper pipe, how do you know (
KNOW, not just assume, but
KNOW) that it is suitable ? It might have the BS number stamped into it, how do you KNOW that it's not a bad batch of pipe ? OK, bit of a strawman, but it's an unknown unknown - well actually, in this case for some of us it's a known unknown. Can't have a bad batch, well
s**t happens - BTW, according to the reports, 4 million metres of cable wasn't pulled from the supply chain so is assumed to be in use, that's 100 times around the earth

Happens to
pipe as well, and dunno if it was
this sort of problem, but our local health centre was closed not long ago for all the plumbing to be replaced after multiple failures.
So, without the metallurgical knowledge to assess a piece of pipe, you assume it's OK, but there is no 100% guarantee.
Yes, it's a strawman argument, but it's in response to your crazy argument that appears to state that it's impossible for someone who hasn't done a specific course and got a specific qualification to be able to do a certain task, and that if you held that ticket, then there were no unknown unknowns. Is that your argument, or are you backtracking on that ?
Then what are those legally required tests before something is plugged in. Or are you just going to swerve any questions again?
Much like you are bringing in codes etc. to gas work ?
There are tests (I've mentioned them already) which you need to do in order to ensure that the electrical works are reasonably safe. If you don't do them, then you can't state that the electrical work is safe. No, BS7671 is not law, but complying with it is generally going to stand you in good stead if hauled up under the various consumer protection and health & safety laws. If you ignored it, not done basic checks, and s**t happens, then you will have broken one or more of those laws.
Would have been interesting to see what the fitter thought he read.
I don't think he had, just assumed as they all used to say "must use FCU"
I have never stated that anywhere. Lying doesn't help your case.
I'm not lying.
You have made it clear that in your opinion, it's impossible for someone who hasn't done a non-statutory course to gain a non-statutory qualification can comply with the law. So that means you think compliance with a non-statutory "something" (you quoted it, I c.b.a. to go and look for it) is essential.
Are you disputing that part ? You've made it very clear that without those non-statutory things, it's
impossible to be competent to (e.g.) solder a pipe fitting, and hence cannot comply with the gas safety regs.
But then you also appear to be happy that non-compliance (note, non-compliance, not just "hasn't got a ticket but is complying anyway") with a different non-statutory "something" (e.g. BS7671) is OK. You clearly don't see any need for any tests before connecting a cooker or boiler to it's power supply, so you don't appear to have a problem ignoring a different non-statutory "thing" when that suits your argument.
So, which of those are you backtracking on ?
EDIT: BTW, one specific electrical regulation would be the Building Regulations "P1. Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury." That's a law (regulation), not a non-statutory standard (BS7671), and applies in all residential properties. BTW, that's also the entire extent of Part P.
The approved document makes heavy reference to BS7671, but does allow for alternative means of compliance - but then you would need to be able to show that the alternative was reasonable and offered equivalent protection as would have been achieved by following BS7671.