Understanding AC Current for Beginners

[b.shahvir]

Briefly: I am not referring to a Residual Current Device, which compares Live and Neutral currents. These did not exist at a time when transistors were not common. This device, as I keep saying, measured current flowing down the Earth wire from the consumer unit to the Earth spike. It was very insensitive but sufficient to do the job that a fuse could no.

It was known as ELCB (Earth Leakage Circuit Breaker). They were used several decades back, but now have been completely replaced by the more sensitive and fast acting RCCB's (Residual Current Circuit Breakers)