Hi Rich and a few others on this topic. you wrote: <The RCCB/ELCB is all-magnetic rather than electronic. It requires 20 mA or more to operate. The North American electronic type built into an outlet requires only 5 mA to operate.>
In the UK we use 30mA for people protection on RCCD's, this is because the onset of ventricular fibrilation will occur with a very high level of probability at currents flowing around heart muscles above this. 50/60Hz is about twice as dangerous as d.c., it being the Change of Current that has the physiological effect, i.e. d.c. is dangerous above 60mA. (I'm ignoring I^2R effects for this purpose). The danger is also related to the actual time the current is flowing, and particularly relevant to the moment in relation to the actual phase of the heart beat. I.e. it's quite possible to be hit by lightening and just walk away, albeit with your trousers on fire. Electronic RCCD's are not used in the UK because of their lack of intrinsic safety, i.e. safety is related to fallible electronic components, and also the increased sensitivity can cause nuisance tripping when highly inductive loads are switched on, the most common being the trip that feeds the freezer switching off when the food gets too hot! The rationale being that it's better to have no RC protection at all, than rely on RC protection that may have failed. A tuppence worth I think, certainly no more... Chris Dupres Surrey, UK.
