TN-C-S? No, TN-S.

[HandySparks]

Thought this might interest some. Doing a CU change. Took a quick look at the supply head, saw the earth terminal on the side and assumed TN-C-S. When the chap from EDF turned up to change the meter and connect to my isolator, it turned out to be TN-S. It looks like the underground supply cable is split concentric; you can see the black insulated strands to the neutral terminal and bare copper to the earth terminal.
Ze was 0.17ohm, Z line was 0.18ohm, so testing wouldn't really have revealed what the earthing arangement was. By the way, does anyone know if there's a standard symbol for the line impedance, line to neutral?

 

[Amp David]

Love them coloured meter tails

 

[Silly Sausage]

Nowt in BGB.
Could call it Z[SUB]LINE[/SUB] I suppose...?
or Z[SUB]LN



[/SUB]
You would have to define whatever you use in any documentation.

 

[somersetsparks]

Is it a flat by any chance?

 

[HandySparks]

Is it a flat by any chance?

Nope, 4 bed house built in about 1970. I'll put some more pics up in "Show us your installs" later. By the way, it's a 60A BS88/BS1361 fuse.

 

[somersetsparks]

I have personally only ever installed split con for risers in flats but thats on recent jobs.

 

[Knobhead]

Although they don’t use split concentric now, something sticks in my mind about them using it around that time. we were told about it at EMEB’s training collage, they stopped using it due to the outer serving and neutral insulation getting damaged leaving a TN-C-S connection in effect.

 

[Richard Burns]

Sneaky one that, must remember the possibility, Cheers.
It is always getting harder to differentiate by measurement with the PME of the supplies.

 

[Knobhead]

As I say Richard, it was only a short time that they were used. A bit like aluminium wavecon cable, that was a disaster as well.

 

[somersetsparks]

As I say Richard, it was only a short time that they were used. A bit like aluminium wavecon cable, that was a disaster as well.

The only use our lot have for split con is for rising mains from a ryefield in ablock of flats

 

[Knobhead]

I could be wrong about them using it U/G. It was something that was stuck in the back of my mind from EMEB 20+ years ago.

 

[somersetsparks]

I could be wrong about them using it U/G. It was something that was stuck in the back of my mind from EMEB 20+ years ago.

Don't reckon your far off mate, I have seen it fed in ducts before (from ryefield) between these little bungalowish sort of things at a 'scheme' for mentally ill people. I bet theres a few like it but you never see them as most people would assume PME seeing a concentric and a PME style cutout.

 

[HandySparks]

I could be wrong about them using it U/G. It was something that was stuck in the back of my mind from EMEB 20+ years ago.

This one's definitely underground. Comes up through the concrete floor of the garage.

 

[keniff]

Love them coloured meter tails

I love the finer multicore tails, they are nice to work with

 

[Knobhead]

Nothing to do with this thread. Trying to move another down the list