"jim_in_sussex" wrote
| 3. Termination: The house end is no problem as that connects
| into a metal enclosure which I know how to connect, but how
| do you connect the garage end into a standard plastic consumer
| unit? ... Common advice seems to be to avoid using the house
| earth, but if possible I'd like to avoid the work involved
| in installing an earth rod. The house supply is 100amp PME/TN-C-S.

AIUI PME earths should not be exported from the house. It would be normal to
use 2-core SWA, use an earthing gland at the house end so that the armour is
earthed, use an insulating gland at the garage end so that the armour is
insulated. The CU is then earthed to an earth rod (TT) and all circuits
should be RCD protected. If you use power tools in your workshop you should
consider discrimination between lighting and power circuits, so that in the
event of an RCD trip you are not left in the darkness with power tools
spinning down. An alternative might be a couple of self-contained emergency
lighting units.

Owain