There's far more fiction here than there ever was in War & Peace, I back up my arguments with all available statistics, British Standards and years of experience installing perfectly safe TT installations that meet the requirements of those standards.
Of course, the requirements are guided minima and if anyone wants to fill up a garden with copper to slavishly attempt to attain Ra values akin to a TN system then go for it but at least ponder beforehand the futility and costs of the task!
So where's the fiction?? You back up your arguments with ''Statistics'' haha!!! Who's statistics?? have you never heard that old saying about Statistic's, it basically tell's you Never to trust statistic's and for very good reason. The very same figures, can be made to say anything the authour wants them to say, ....An that's a well proven ''Fact!!''
Are you really trying to convince me that a 1m rod with a Ra of 200ohms is and will remain safe for the duration of it's lifespan, even when the paralleled bonding pipes are replaced with plastic services?? Come on IQ pull the other leg, it's got bigger bells on!!
Now, no-one is saying you should slavishly attempt to obtain TN values from a TT system, or filling a garden with copper, that's twisting what i have said here, they are Your words trying to be clever, NOT mine!! What i will say is, in generally found garden British soils, i could in most circumstances achieve a below 10ohm Ra with a maximum of 2 twin rod positions. If that is filling a garden with copper, so be it ...lol!!
What i'm also saying is, Not even trying to improve, a crap Ra value with a deeper rod, or at a second location, to me doesn't say much for an electrician that's installing/creating a TT system. Also a bad Standard, is a bad Standard, whatever way you like to dress it!!
If you have, with your years of experience, installed TT systems that are anything like those that seem to be the norm these days in the UK, ie, a single 1m rod with an Ra of around the 200 ohm mark, i'm sorry, your fooling yourself big time, thinking that's perfectly safe!! That would only be safe as such, while a the prime protection RCD was functional... It sure ain't gonna be safe when it isn't functional!!!
The only way i would feel even half happy leaving such a TT system in place, is if the CU in question, had an up-front 100mA S type RCD and all the circuit protective devices were RCBO's. At least then you have 2 RCD devices covering your bum, unlikely that both will fail, but then again, it's not unheard of either...
