Damaged main earth cable - advice please!

[RWhites]

Hi all.
I've just removed an internal brick wall adjacent to my mains fuse, meter, and earth connection. I've now noticed that the main earth cable clearly took a bash - despite being as careful as I could. There is a nick in it, which has gone through the insulation and has broken (at least) a few of the strands of cable, but it is difficult to see how many. The cable is a 10mm sq cable. It is safe to say that at least half of the cable is intact - probably more.

My plan was to replace it entirely, but having taken up the floor to do this, I can now see it disappears down a hole under the outside wall alongside the blue plastic water main, so I can't get to the source connection.

My alternative plans now are:
a) Wrap the nick in the cable with insulation tape and leave it at that.
b) Make a joint in the cable to replace the damaged section.

If b), what connecting method should I use? I have some 30A j-boxes already, would they be any use for this?

Many thanks in advance.

 

[Lectrician]

10mm through crimp:

Ratchet crimper:

Are you sure it's your main earth and not a bonding conductor?

Photo?

 

[RWhites]

Are you sure it's your main earth and not a bonding conductor?

Errm. No, I've no idea!

My electrical main is an overhead supply from my neighbour's house. It has two cables - the main supply and an earth. They come into the house just above head height, and go to the main fuse board. The main fuse has a big yellow sticker on it warning of multiple earthing.

The main earth j-box on the main fuse-board has one earth cable going underground - out of sight (the problem cable), one coming in with the overhead supply, one going to the (old) metal domestic CU, and one to another j-box serving the meter.

You tell me....?!

 

[viewer]

Don't cut the cable, but splice a new piece if 10mm from before to after the nick using clamps.