I found a paper (from South Africa) on the history of the RCD. I thought it could be of interest to anyone who wants to know how the RCD came to be.

http://www.cbi.co.za/papers/24/CBI2.pdf


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By the way:

A European RCD/GFI look like this

[Linked Image from i.kth.se]

This particular one is the cheapest you can buy here. The two pole $20, the four pole $30

Although it's not printed on the device, the manufacturer reports the trip time to be 100ms at 30mA and 40ms at 150mA, whereas more expensive models trip in 40 ms at 30 mA.

[This message has been edited by C-H (edited 11-08-2002).]