Delayed RCD main in a plastic enclosure with 30ma sub-main RCD. However, clearing longer than 0.035 seconds of the main RCD may not be fast enough in areas of lowered skin conductivity.
In all honesty I'd like developed countries to move away from TT supplies. TT, TN-C-S and PME are simply a choice between cons in a world where DNOs do not want to provide more conductors than it takes to get the lights on. TN-S provides all the advantages of superior fault clearing given by TN-C-S, but without parallel earth currents or the risk of exposed parts becoming live should the neutral be lost.
Delayed RCD main in a plastic enclosure with 30ma sub-main RCD. However, clearing longer than 0.035 seconds of the main RCD may not be fast enough in areas of lowered skin conductivity.
In all honesty I'd like developed countries to move away from TT supplies. TT, TN-C-S and PME are simply a choice between cons in a world where DNOs do not want to provide more conductors than it takes to get the lights on. TN-S provides all the advantages of superior fault clearing given by TN-C-S, but without parallel earth currents or the risk of exposed parts becoming live should the neutral be lost.
