What is the neatest way to split a submain?

[John Rumm]

Subject says most of it ;-)

Just had described to me what sounds like a 60A submain to an old rewireable fuse CU. It will need splitting to feed a new mini CU for a

9.5kW shower.

I have not seen the setup yet, so I don't know how the incoming submain to the CU is wired, but there is a fair chance that it is not wired in tails but either T&E or SWA instead. Assuming this is the case, which way do you favour splitting it? 60A JB, Adaptable box, Henley and separate earth terminal, or straight from the incomer terminals on the first CUs main switch (assuming there is space)?

[Andrew Gabriel]

If it feeds an old rewirable fusebox, take the opportunity to replace the fusebox with a modern one which is big enough for the new circuit. Note that 9.5kW will be using 2/3rds of the

60A submain's capacity -- you will need to check for loadings imposted by existing circuits, and the load the extra 40A is going to put on the upstream consumer unit (if it comes through one) and the upstream supply main.

[John Rumm]

Tis one option (and the way I would do it if it were mine), but I am expecting that the quickest low cost option is going to be the favoured approach ;-)

Its a commercial premisis with three phase in as the main supply. I have seen that part of it in passing, and it did look like it had been quite recently updated. I doubt there will be any problem with upstream capacity. The current sub CU only has four circuits on it IIUC, so with luck nothing too heavy.