Earth to back box first

[PrenticeBoyofDerry]

Could I test by running a lead from the earth on the nearest 13a socket to the light earth and vice versa?

you could test an earth of nearby socket but if you to do this you would also need to confirm that the socket had a path to earth.

 

[Squiddley57]

But then reverse the process or run through a sequence of testing light to socket and socket to light. Means that the lead need not be 30m long?

 

[mfarrow]

Turn off power to the circuit at the consumer unit.

Test to ensure the circuit is dead at the MCB output.

Connect a temporary jump lead from the MCB output to the main earthing bar of the consumer unit.

Go to the switch and check for continuity between the live wire coming in and the CPC in the backbox.

If all is well, disconnect the temporary jump lead and carry on.

 

[PrenticeBoyofDerry]

Turn off power to the circuit at the consumer unit.

Test to ensure the circuit is dead at the MCB output.

Connect a temporary jump lead from the MCB output to the main earthing bar of the consumer unit.

Go to the switch and check for continuity between the live wire coming in and the CPC in the backbox.

If all is well, disconnect the temporary jump lead and carry on.

identify the CPC/earth and live line at the CU/Board.
Isolate the protective device, test the top of the device is dead, then remove the live/line conductor and terminate this into the earth busbar, then go to each switch testing at low ohms across live/line and CPC.

Damn site safer than linking across MCB!

 

[mfarrow]

Ah, didn't spot that in your post.

Without seeing the OP's CU, I wouldn't predict what kind of rats nest he has present, and therefore how much poking in of ones finger's I'd have to do to grasp enough live to take it to the earth bar.

Either scenario is still safer than working on a circuit with just the MCB down.

 

[PrenticeBoyofDerry]

They could still disconnect the conductor from the MCB, which should not be such a great task, even if a rats nest is present at the CU and either connect to earth busbar if easy or bridge across the conductor end to busbar.
It is very much safer than having a direct link across a MCB.

 

[securespark]

If it's lighting, I would terminate at the box and run a fly from there to the plate.

But if it's power, the cpc should go direct to the plate with a fly back to the box.

Strictly, a fly isn't needed if the box has at least one fixed lug, but I consider it good practice nonetheless.

 

[mfarrow]

It is very much safer than having a direct link across a MCB.

The tone you apply seems to imply that this practise is unsafe. Granted your method may be more 'fool proof' but there should be no reason why a circuit should not be independently earthed with the in-feed MCB in the off position and still connected in circuit.