Most interesting, I have been having a look through a load of old stuff that i have kept, your quite right about the old ElCB,s and as I said in a previouse post I can remember installing circuit breakers in the very early 60s. Yet looking in the various regs books of the time twelfth edition there's very little direct reference to circuit breakers it was a mysteriouse tecnology then in fact the first trip charcteristics didnot appear in the regs until 1981. We just blundered about installing by name until then dont think we even recognised that some took longer than others to operate. Oh happy days.
