I want to change the supply to an annex and a workshop. The house supply conveniently already supplies two DBs via some Henleys. I want to connect the Henleys via tails and a switch-fuse to SWA and run this submain to the workshop, past the annex. I want to supply (eventually) the annex by tee-ing off the submain using an external JB - something like
The earth is currently exported to both buildings, but the workshop is 60 metres from the house, so I presume I probably ought to TT it.
1) Can I tee-off a submain like this? 2) Any considerations for testing?