TN-S No Main Earth Terminal

[charlie76]

Evening All. I am about to carry out a domestic rewire to a property which has TNS earthing. The DNO has recently done a bit of work installing a new isolator, smart meter, contractor for Econ 7 switching etc and tidied up their end of things a bit. There is no MET at present and everything (Main bonding and main earth) seems to have been earthed at the incoming sheath. Pity DNO didnt install a new MET but they didnt.

Am I allowed to connect to their sheath directly or should I ask them to provide a MET and the 16mm from this to their sheath? I would prefer to have a MET, just looks tidier than the connection direct to the sheath as currently made in the attached photo.

 

[YoungScud]

...although I see the meter fixer had the sense to move it back...

 

[davesparks]

That really irks me. I can never get my head around why someone puts a single phase supply on L1 or L2 When L3 would have to be pulled anyway to remove the neutral cover.

Presumably it is because they don't want all of the loads being put on L3

 

[YoungScud]

That wouldn't normally happen. Usually, when only a single phase supply is needed, only a single phase cutout is installed. Before I became a trainer, I worked in metering for over tewenty year and we had a large number of 'four in a block' types of flats in our area. They usually had a three phase supply in one of the flats feeding submains. The flat with the incomer was never fed from L1, always one of the other two. This meant that to get at the neutral cover, two flats had to be disconnected. It was infuriating and unnecessary.

 

[davesparks]

That wouldn't normally happen. Usually, when only a single phase supply is needed, only a single phase cutout is installed. Before I became a trainer, I worked in metering for over tewenty year and we had a large number of 'four in a block' types of flats in our area. They usually had a three phase supply in one of the flats feeding submains. The flat with the incomer was never fed from L1, always one of the other two. This meant that to get at the neutral cover, two flats had to be disconnected. It was infuriating and unnecessary.

That sounds like bad design/planning on the original installers part.

There are a lot of houses around here with three phase supplies in PILC with only one phase used, and a lot of them are on very old cutouts

 

[YoungScud]

It was exactly that, bad planning. Jointers who should have known better.