There's another failure mode for TN-S - these days with even domestic installations having many electronic appliances it's common for the standing earth leakage (sorry, protective conductor current) to reach dangerous levels (e.g. 50mA or more) - so a broken PE in the supply can make the installation's metalwork hazardous in much the same way as a broken PEN conductor in a TN-C-S system, if with somewhat lower currents involved.
If you want a less hazardous earthing system - there was one approach suggested (I think it was in one of the Cahiers Techniques) that introduced a deliberate resistance between the supply star point and Earth (like an IT system) but with the consumers' earthing system directly connected to the supply earth electrode (as in TN-S). The result of an L-PE fault is then that the voltage on the insulated live conductors goes somewhat awry w.r.t. true Earth but the earthing system itself remains at pretty much true earth potential. Earth fault currents are very low, so very negligible potential differences between even widely spaced parts even during a fault. RCDs are used automatic disconnection - but only to provide reliability - as they're not needed for ADS to provide shock protection.
There's another failure mode for TN-S - these days with even domestic installations having many electronic appliances it's common for the standing earth leakage (sorry, protective conductor current) to reach dangerous levels (e.g. 50mA or more) - so a broken PE in the supply can make the installation's metalwork hazardous in much the same way as a broken PEN conductor in a TN-C-S system, if with somewhat lower currents involved.
If you want a less hazardous earthing system - there was one approach suggested (I think it was in one of the Cahiers Techniques) that introduced a deliberate resistance between the supply star point and Earth (like an IT system) but with the consumers' earthing system directly connected to the supply earth electrode (as in TN-S). The result of an L-PE fault is then that the voltage on the insulated live conductors goes somewhat awry w.r.t. true Earth but the earthing system itself remains at pretty much true earth potential. Earth fault currents are very low, so very negligible potential differences between even widely spaced parts even during a fault. RCDs are used automatic disconnection - but only to provide reliability - as they're not needed for ADS to provide shock protection.
