Type A rcd . EICR coding ? etc

The Blakley paper is interesting but again nothing like the situation we find in domestic premises. The DC traction supply of 750V is quite smooth, is of a high voltage, and very large power availability. Circulating currents in Earth conductors and even through the Earth itself are inevitable, but the range will not be very great away from the railway. It looks to me as though someone is looking for a reason to define a potential problem in domestic premises, which has none of the conditions cited in the Blakley paper. Domestics do not have traction supplies, complex Earth paths etc. Earth bonding is by definition to a single point per premises, which do not have a great extent. Circulating DC current will probably be very small, particularly as many domestic items are class 2. I also see no reason to blame electronic devices, many ones complying with the EU directives on power do not have the internal circuitry shown in BS7671, and higher power items like induction hobs certainly don't. It MAY be possible to work out a fault which "could" produce some DC in the case of a fault, but this could not be much as the Fuse/CPD would trip due to excess power consumption.


I would like someone to explain to me why this is suddenly a problem, we have had lots of electronics in homes for at least 30 years, and RCD protection of the simplest kind (1 or 2 per property, type AC) have proved to be useful, and the number of accidents is tiny. Are we again trying to reduce 1 per million to zero per million by throwing money at the problem? Would this make any difference anyway?

The Blakley paper is interesting but again nothing like the situation we find in domestic premises. The DC traction supply of 750V is quite smooth, is of a high voltage, and very large power availability. Circulating currents in Earth conductors and even through the Earth itself are inevitable, but the range will not be very great away from the railway. It looks to me as though someone is looking for a reason to define a potential problem in domestic premises, which has none of the conditions cited in the Blakley paper. Domestics do not have traction supplies, complex Earth paths etc. Earth bonding is by definition to a single point per premises, which do not have a great extent. Circulating DC current will probably be very small, particularly as many domestic items are class 2. I also see no reason to blame electronic devices, many ones complying with the EU directives on power do not have the internal circuitry shown in BS7671, and higher power items like induction hobs certainly don't. It MAY be possible to work out a fault which "could" produce some DC in the case of a fault, but this could not be much as the Fuse/CPD would trip due to excess power consumption.


I would like someone to explain to me why this is suddenly a problem, we have had lots of electronics in homes for at least 30 years, and RCD protection of the simplest kind (1 or 2 per property, type AC) have proved to be useful, and the number of accidents is tiny. Are we again trying to reduce 1 per million to zero per million by throwing money at the problem? Would this make any difference anyway?