I have bought an ELCB and a mini DB board for a small solar/inverter project. My understanding is that an ELCB trips when there is a potential difference between earth and neutral. The diagrams I've seen online all show an earth connection to the ELCB, for example:
However, when I try to connect up my ELCB, I can only see the four main connections (live and neutral, in and out). Here, pics:
There are no other connections apart from those four. How is the ELCB earthed?
The only way I can think of is through the connection to the metal rail on which all the breakers are installed. However, the backing of the breaker does not seem to be conductive.
Best Answer
The Onesto KRC3 is a residual current circuit breaker and these types of devices operate by measuring a difference current flowing in live and neutral rather than specifically measuring a leakage current to ground.
The above description is taken from here
The difference between live and neutral currents IS earth current in effect: -
As you can see from the above, EARTH is included but isn't needed and some devices down provide a thru-going connection for earth at all. In north America they are called ground fault circuit interrupters: -