- 3 Nov 2006
- Reaction score
I believe the RCBO is designed for two things:
1 - to protect the radial circuit from exceeding its power draw. With 1.5 mm cable rated for 15 amps then a 6amp fuse should protect it very well.
2 - to protect the circuit from appliance faults such as power surges or short circuits etc.
2 is not correct , it has an RCD function that detects earth leakage faults.
The RCD function compares the current on the Live conductor with the current on the Neutral conductor. If they are the same but opposite direction ( as they will be in a fault free situation ) then the RCD will not trip. If they are different and that difference is 30 milliAmps or more then the RCD will trip. This happens when current is leaking to ground or elsewhere from the circuit(s) protected by the RCBO.