TN-C-S or TN-S?

[P&Q]

Hi everyone,
Just wanting to confirm something, could you please let me know if these pictures are describing a TN-S or TN-C-S system?
Thanks in advance

 

[topquark]

PIC 1 is TNS. PIC2 looks like a TNS also (despite the label suggesting it's PME; there is no separation at the head and the connection to the MET is from the sheath).

 

[aptsys]

The sheath could be connected to the neutral in the head, so could quite conceivably be TN-C-S. I've seen them do this a couple of times where the sheath on the PILC has lost it's earth connection somewhere, so they've joined the two and at the same time maintained the protection the sheath gives.

They wouldn't label it for nothing.

 

[aptsys]

Having spoken to a local jointer, they will never supply TN-C-S through PILC except under certain circumstances such as that outlined above (and even then only if certain conditions are met), and they will always use 4 core cables in the street where houses are supplied by PILC, so it is most likely TN-S.

 

[Noton1205]

They are both TNS if it was a pme it the dno would not use earth braid they would use 16mm cable that is sheathed. If this was a pme then that braid would be an exposed neutral conducter

 

[nickblake]

TNS , word of warning chaps when testing your Ze on what looks like a TNCS with the earth block on the side of the cut out , switch off the supply disconnect all main Earth and main bonds and then test across the in terminals of the isolator and the earth block this will confirm that the earth block is connected to earth either TNCS or TNS , reason i say this is over the past few month i have come across the same error in connecting the earth to an unconnected cut out earth block , the one i recently did looked like a TNCS but was infact a TNS with the original earth cut off , the earth was reconnected by the DNO with the earth running into the cutout and to the earth block ,

 

[Engineer54]

The Ze reading is no reliable indication of whether it's TN-S or TN-C-S, IMO. There is a large 60's estate near me where every house is a TNS. There are sub-stations sprinkled across the estate and I've got Ze readings between 0.08 and 0.23 in various houses.
This is the cutout fitted in these houses:
TN-S not TN-C-S - Shared photo album - PhotoBox

That would have fooled me, i would definitly have taken that cut out to be a PME supply!!!

 

[truckster]

Thats why its important to measure the l/e and l/n impedance, some of these cut outs are split inside and look like a PME connection but aren't. Seen quite a few in the rural areas down here.

 

[JLD]

Hi everyone,
Just wanting to confirm something, could you please let me know if these pictures are describing a TN-S or TN-C-S system?
Thanks in advance

They look both to be TN-S to me but I would seek confirmation rather than just relying on measurement.

 

[JLD]

The Ze reading is no reliable indication of whether it's TN-S or TN-C-S, IMO. There is a large 60's estate near me where every house is a TNS. There are sub-stations sprinkled across the estate and I've got Ze readings between 0.08 and 0.23 in various houses.
This is the cutout fitted in these houses:
TN-S not TN-C-S - Shared photo album - PhotoBox

I have also come across several of these types of service heads years back. The cable coming in is a three core and the head has three separate chambers within it. It taught me never to assume TN-C-S just because the earthing conductor came from the head. Similar PSCC and PEFC readings seemed to work for me to confirm TN-C-S systems.