Could some one please tell me in the event of an earth fault, what will operate and disconnect the supply of an istallation with earthed equipotential bonding and automatic disconnection where the circuit is not protected by and RCD?
You must be in the UK... differences in lingo and codes may cause you to get little response here. rcd is the equivalent of an arc fault breaker I believe. These sense potential and potential change and trip prior to full ground fault.
In the case of a full ground fault a regular breaker would still trip... as current increases with load and trips the breaker. Much more flows to ground before tripping and it also takes longer to trip. Sounds like a silly answer but I think that was your question, no?
RCD is I think equivalent to our GFCI. They operate by detecting the current on the supply and return wires. If the current is not within 5ma then GFCI will trip.
If you don't have a GFCI then only the over current protection device(OCPD)ie. breaker or fuse will be protecting the circuit. The current needs to exceed the fault current of OCPD before the circuit is opened. Otherwise current will continue to flow.