I'm doing some theoretical calculations, and I'm debating that the 5 second disconnection may have to be lowered in circuits 32-225 amps where fed from an extensive LV supply network. IMO, The voltage may not sag far enough at the supply terminals to result in a touch voltage of 50-75 volts to remote earth. On the other hand, large circuits may be relaxed to 10 seconds and 15 seconds with no ill effect from a basis of shock protection.
I'm also debating that adiabatic limits make an assumption of 10 seconds disconnection for circuits 63 amps and below on the basis of external Ze changes.
Granted these changes would be on orders of magnitude more prudent for NFPA-70 and CSA C22, however it is still worth considering.
Right now I am putting together a frame work for various touch voltages for given network configurations and interior wiring practices seen around the world.
