The DNO network system categorised as Hot site or Cold site (430V or 650V ~ in case operating voltage of 33kV with sensitive earth faults cleared within 200ms). My submission is the standard always talks about the voltage (i.e pressure) or 30mA ELCB limits in case of housing earth leakage protection(i.e current). I presume either voltage or current are not alone cause for safety hazard. It is the product i.e voltage*current or V*I*t which causes burns on human body. Hence may i suggest in this forum to review this and consider the subject resistivity+ time aspects while calculating the "Step & touch power / energy" rather than "Step & touch voltage" as is being mentioned in the earthing standards. The additional variables of resistivity& time would help us to choose the appropriate insulating materials and relay settings and enhance human safety. Happy to discuss further, to bring this idea to shape and benefit wider community.
a) hot and cold are telecoms standards, concerned with potential transferred away from the substation on metallic circuits, so they're not directly related to safe touch/step potential
b) as more learned commentators than I have noted, the issue is about the low currents which cause fibrillation. The limits for what touch/step voltages are deemed to be safe can be higher than the hot/cold levels, because the safe limits make assumptions about the impedance of the unfortunate person involved, their footwear, and the surface they're standing on. That's why there are different permissible voltages for different surfaces: there's also a completely different (and more stringent) set of limits for railways, because they've made different assumptions about those impedances
There are IEC standards for all of this, so I suggest that we avoid re-inventing the wheel
a) hot and cold are telecoms standards, concerned with potential transferred away from the substation on metallic circuits, so they're not directly related to safe touch/step potential
b) as more learned commentators than I have noted, the issue is about the low currents which cause fibrillation. The limits for what touch/step voltages are deemed to be safe can be higher than the hot/cold levels, because the safe limits make assumptions about the impedance of the unfortunate person involved, their footwear, and the surface they're standing on. That's why there are different permissible voltages for different surfaces: there's also a completely different (and more stringent) set of limits for railways, because they've made different assumptions about those impedances
There are IEC standards for all of this, so I suggest that we avoid re-inventing the wheel
