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.
I think 50mv is enough to stop the heart and RCD protection is 50mA , so touch voltages must be well below this , at the other end of the scale a lightening strike is millions of volts, and the burns are the resistance of the tissue to electrical voltage flow, these burns are in turn sufficient to damage tissue and the body may fail due to the damage caused , there is a great picture of the collar of lighteningstrike injury (they survived pretty well) and its just like a still from a Tesla coil , like a madlrbrot plot , lots of fractal flames from one central point and completely geometric , however most skin patterns found on lightenstrike injuries are not as neat as this very lucky person.
There is a resistivity figure for human tissue (works for animal tissue too I think)
Most U.K. R.C.D.s are rated at 30mA and operate within 40mS. They will normally prevent death of a human.
The many types of shock occurrences from mains' electrical supplies in the home or industry vary so much due to circumstances, that solid test results are difficult to achieve. Many variations exist due to individual circumstances such as body parts involved, path of shock current, whether the body is dry or wet, whether the person is wearing insulating footwear or gloves, standing on an insulating carpet or on the soil etc.
I think 50mv is enough to stop the heart and RCD protection is 50mA , so touch voltages must be well below this , at the other end of the scale a lightening strike is millions of volts, and the burns are the resistance of the tissue to electrical voltage flow, these burns are in turn sufficient to damage tissue and the body may fail due to the damage caused , there is a great picture of the collar of lighteningstrike injury (they survived pretty well) and its just like a still from a Tesla coil , like a madlrbrot plot , lots of fractal flames from one central point and completely geometric , however most skin patterns found on lightenstrike injuries are not as neat as this very lucky person.
There is a resistivity figure for human tissue (works for animal tissue too I think)
Most U.K. R.C.D.s are rated at 30mA and operate within 40mS. They will normally prevent death of a human.
The many types of shock occurrences from mains' electrical supplies in the home or industry vary so much due to circumstances, that solid test results are difficult to achieve. Many variations exist due to individual circumstances such as body parts involved, path of shock current, whether the body is dry or wet, whether the person is wearing insulating footwear or gloves, standing on an insulating carpet or on the soil etc.
