Well, this is in the freshly published NRS 097-2-1:2024
So it would be strange if the next version of SANS contradicts it…
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Aaah that is Leon Roos at the Association of inspection authorities? Don’t know him from a bar of soap, but I did look into it a bit to see if he has any sort of seniority in this debate.
This issue repeatedly comes up, but I honestly don’t see how the requirement around the TN bond can be relaxed. If it is bad to have working current on an earth conductor, then such a change is simply untenable. People may ask for it, and it may be considered, but an electrical engineer with some seniority will always shoot it down.
NRS-097-2-1 also takes a lot of inspiration from VDE-AR-N-4105 (German code), and that code is pretty adamant about it too.
Backup generator requirements have also required it for ages.
The American grid code is also pretty clear about bonding only on the main service, not on sub-boards.
I mean, I don’t want to just shoot it down. Maybe it is considered the lesser evil (between having no bond at all during islanding, vs having two bonds), but it seems contrary to every code I know 
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Apologies, a typo, Roos not Ross