Storm Glands.

AJJewsbury: 
 

Humm, I wonder if he did find a 100mA S-type RCBO for the garage submain, or noticed last sentence of 542.1.3.3.  … ah the perils of installing first and thinking about the design later. Maybe he didn't want a brass gland into a steel CU after all.

Very strange that the faults caused by “someone” tugging the cables back towards the CU and catching the capping weren't noticed by the householder previously.

   - Andy.

It was a split load consumer unit. The circuits to the right were not R.C.D. protected in the old board. And the damaging of the earthing conductor would cause no problems, even if it did earth up the metal capping. If a T.&E. cable from the right was partially damaged and the fault resistance was high to the metal capping an M.C.B. would not operate. Fortunately the wall was dry so could not become dangerously live.

Would we have found the problems, and further investigated,  as the insulation resistance was about 2M Ohms so complied?

Z.

AJJewsbury: 
 

Humm, I wonder if he did find a 100mA S-type RCBO for the garage submain, or noticed last sentence of 542.1.3.3.  … ah the perils of installing first and thinking about the design later. Maybe he didn't want a brass gland into a steel CU after all.

Very strange that the faults caused by “someone” tugging the cables back towards the CU and catching the capping weren't noticed by the householder previously.

   - Andy.

It was a split load consumer unit. The circuits to the right were not R.C.D. protected in the old board. And the damaging of the earthing conductor would cause no problems, even if it did earth up the metal capping. If a T.&E. cable from the right was partially damaged and the fault resistance was high to the metal capping an M.C.B. would not operate. Fortunately the wall was dry so could not become dangerously live.

Would we have found the problems, and further investigated,  as the insulation resistance was about 2M Ohms so complied?

Z.