Ok, got a building with sub-board 2 supplying sub-board 3 in an adjacent outbuilding. Now 2 ccts are supplying lights and electrics in the shed part with a small kitchen and toilet area. 1 cct is linked to main building lights and 2 way switched so you can turn lights on during dark winter months beofre stepping outside. The other cct is the sub-main to the a small board supplying a couple of water heaters and a few sockets for fridge kettle etc, etc. Both ccts are RCBOd in the main building. There is an earth rod by the kitchen connected to sub board 3. Sub board 2 is linked to another rod at main incoming point. System is single phase, CPC in sub-main is not connected.
Now I was under the impression that sub-board 3 should have RCd protection at that point, but is this necessary given all circuits are 30mA protected prior to this point?
Another interesting thing here is that MEB for water is connected to sub-board 3 where copper pipe emerges from ground. Rest of pipework in main building has been re-done in plastic. As the electrical supply is linked to main incoming point in main building, it would be normal to run MEB back to main earth, but as the only extraneuos conductive parts are next to sub-board 3, this seems a little pointless to me?
Your opinions please
Now I was under the impression that sub-board 3 should have RCd protection at that point, but is this necessary given all circuits are 30mA protected prior to this point?
Another interesting thing here is that MEB for water is connected to sub-board 3 where copper pipe emerges from ground. Rest of pipework in main building has been re-done in plastic. As the electrical supply is linked to main incoming point in main building, it would be normal to run MEB back to main earth, but as the only extraneuos conductive parts are next to sub-board 3, this seems a little pointless to me?
Your opinions please
