Question about sub-main sizing

nothanks · 2019-02-07T14:24:42+00:00

My TNC-S supply enters in the attached garage, where the tails are split to a CU (in the garage, feeding: the kitchen, cooker, utility and a few other bits) and a 60A switched fuse which feeds a 16mm2 sub-main.The sub-main is about 20m long and connects to an ancient fuse board that supplies the house radial and ring outlets. A second fuse board in the same location is connected to one of the MCBs in the CU via a 2.5mm2 cable and supplies power to most of the house lights.My plan *has* been to fit a new CU close to the garage and extend all the cables back to it, but that requires a lot of disruption. I'm now wondering whether I should simply replace the two wylex boards with a single new (RCBO) CU in their present position and feed it from the sub-main. From some quick checks the existing 16mm2 will be OK at 20m for volts drop if I protect it with a 50A MCB. However, from a quick look (more poking around required) the only earth connection seems to be the CPC in the 16mm2 T&E so that will need improving and the disruption involved won't be much less than extending all the circuits, although it will be less work.What do the relevant panel experts think?

Feb 07, 2019 Last reply: 7 years ago 22 Replies

Rate this thread:

ARW 7 years ago

Now imagine what we could have had if Adam had spared a couple more ribs when Eve was created.

Oh, that would be a woman with three t*ts.

Vote

The Natural Philosopher 7 years ago

I thought He was going to say 'I know - you have a brain - you never use that, we will make him out of that!'

Vote

ARW 7 years ago

VBG.

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required