I have a small split load CU in my garage that has become inaccessible due to clutter. There is sufficient cable to move without disconecting anything - but obviously needs to be isolated to work safely.
Its supplied by T+E in conduit from the main house CU and covered by a 40amp MCB.
Over the weekend started to work - so confirmed live. switched off MCB went to confirm dead - now 9.4 volts between line and neutral or line and earth.
Opened CU and checked all the other MCB/RCBO's. The other 40 amp MCB shows similar voltage drop - although this is not connected to any circuit. All the other MCB's RCBO's show no voltage between line and neutral/earth when off.
On removing the unused MCB and bench testing resistance <0.1 Ohm when on and >20Mohm when on. On the 200 Mohm range shows initially 25 Mohm but over 3-5 seconds rises to >200 Mohm.
I have tried to find the impedence of the meter and currently cant locate this info.
The MCB's were all purchased from TLC about 7 years ago when the CU was changed after the previous RCB failed.
Does this mean the 40 amp MCB,s are faulty or are there other tests to check function.
Its supplied by T+E in conduit from the main house CU and covered by a 40amp MCB.
Over the weekend started to work - so confirmed live. switched off MCB went to confirm dead - now 9.4 volts between line and neutral or line and earth.
Opened CU and checked all the other MCB/RCBO's. The other 40 amp MCB shows similar voltage drop - although this is not connected to any circuit. All the other MCB's RCBO's show no voltage between line and neutral/earth when off.
On removing the unused MCB and bench testing resistance <0.1 Ohm when on and >20Mohm when on. On the 200 Mohm range shows initially 25 Mohm but over 3-5 seconds rises to >200 Mohm.
I have tried to find the impedence of the meter and currently cant locate this info.
The MCB's were all purchased from TLC about 7 years ago when the CU was changed after the previous RCB failed.
Does this mean the 40 amp MCB,s are faulty or are there other tests to check function.
