Tncs or TT ?

[jonthesparks]

Does the DNO change TT systems into tncs by changing the head to a tncs cut out and providing met? The Ze I measured was 0.60 and when main earth reconnected reding of 0.40 on the met . There is an earth electrode and 30 mA rcd as a main switch . Is this a TT system or tncs ?

 

[SPARTYKUS]

Picture please

 

[ChrisElectrical88]

Definatly sounds like some kind of T system to me.

 

[jonthesparks]

I meant to , I'll explain it , at ceiling level 2 tails old looking insulated in cotton go into a new grey 1361 cut out .

 

[Guest55]

There is an earth electrode and 30 mA rcd as a main switch . Is this a TT system or tncs ?

dont know whats goin on in the rest of your post but this^^^ is indeed a TT system.
the MET is always fitted / supplied by the consumer but a modern tncs cutout will have an seperate earth terminal , usually linked to the neutral.

 

[yellowvanman]

Does the DNO change TT systems into tncs by changing the head to a tncs cut out and providing met? The Ze I measured was 0.60 and when main earth reconnected reding of 0.40 on the met . There is an earth electrode and 30 mA rcd as a main switch . Is this a TT system or tncs ?

You need to ask the DNO out to make some measurements and if Ok provide TNCS (PME).

 

[kipper]

TT system is a stake in the ground providing an earth and R.C.D. providing protection.
p.m.e. is earth and neutral on same block and readings over 0.35ohms are considered to high and should be reported to supplier (EDF etc) and if p.m.e. is available it should have a note on or near cut out stating p.m.e. is available. some old tn-s systems sometimes have earth block on side of head so look like tn c-s
sorry if ive just told you how to suck eggs.
hope helped.
ta kipper

 

[Engineer54]

To be honest any competent electrician worth his sort, should be able to distinquish a TT system from a TNC-S, both visually and/or by testing.

 

[Kate]

The DNO have been replacing the old meters. When they do they upgrade the head to allow for a PME if possible.

But its not a PME unless the consumer gets an electrician in to make it so.

It sounds to me that you have the potential for PME but are still using an earth electrode.

 

[ChrisElectrical88]

Surely the easiest way of distinguishing this is to measure both the N and E PFC, if there both the same 9 times out of 10 it's PME

 

[Engineer54]

The DNO have been replacing the old meters. When they do they upgrade the head to allow for a PME if possible.

But its not a PME unless the consumer gets an electrician in to make it so.

It sounds to me that you have the potential for PME but are still using an earth electrode.

In most European countries, they insist on a local, ''on premisses'' earth rod. It should be a condition of supply in the UK too. It'll certainly reduce the effects of a broken or high resistance neutral problems on the main distribution cable....

 

[telectrix]

can't see it being TT with a Ze of 0.6 ohms.

 

[Kate]

Its possible. Ive come across lower.

 

[Silly Sausage]

It's possible. I've come across lower.

You are E54 and I claim my £5.

 

[Kate]

What?????