JohnD said:Well, if the RCD is tripping, you clearly have an earth leakage. Did you look to see if the RCD still tripped when the MCB was off? That will tell you if it is Phase/earth or Neutral/Earth.
Did you UNPLUG all appliances in the ring? That will tell you if it is a wiring/accessory fault or an appliance fault.
Did you try halving the ring? That will help you identify where the fault is on the circuit.
Presumably you have already had a visual search for damaged wiring or accesories, including rodent damage under floors, or water ingress, and have tried disconnecting any outdoor sockets or lamps on the circuit, which are at risk of collecting rainwater.
You have probably realised now why the Installation Certificate includes spaces for a lot of test results, and why replacing a CU is notifiable work. If you say you have done CU replacements at work I presume someone else has been doing the tests.
thanks for reply john well the rcd tripped leaving the mcb still on and cant reset it since.
unplugged everything on the circuit and still no reset.
no outdoor light or sockets
and yes as im an apprentice i have a guy with me at all times who tests any work i do
like i said he was going to come and test my cu on monday
this was supposed to be my big test and to be honest i thought it'd be a walk in the park but obviously something is wrong and i do not have the knowledge to know what..