sub main help

[m25maintenance]

im going to rewire a large house. i have decided to put 1 cu in the basement next to the service head and one on landing to serve top floors. i just need to know a few bits. i know i must do ZE at the intake position, but im gona split the tails into a henley block and have a supply to both cu. so do i do two ze tests. any other info would be great. tanx.

 

[Spudnik]

Nope.

Ze is Ze.

It will be the same for both certs that you will have to fill in.

 

[Guest123]

Also you will still need a single means of isolation for the whole installation.

 

[m25maintenance]

tea ill put a 100 amp dbl pole isolator on the tails b4 the splitter block, yes or should i put a dbl pole iso on both tails

 

[Spudnik]

I would say you only need to use the switch fuse (not DP isolator) on the CU running upstairs.

Dont forget to think about installation methods, as this will dictate whether the tails will need RCD or not.

 

[Guest123]

Meter.......100A DP isolator.......henleys.......1 set of tails to adjacent CU.......the other set into the switchfuse for the sub-main to the CU on the landing. It'll need overload protection see.


If you use a Wylex type switchfuse for the sub-main, you wont need henleys as you are able to tail in and out of these as they have a pair of L+N terminals on the supply side aswell as your outgoing load.