When is TNS really PME and vice versa?

[westward10]

If it enters as TN-S you have to consider it as such. But I agree in most cases now it is likely to be PME/TN-C-S outside.

 

[Delboybully]

The thing is the DNO call it pme. We call it tncs. As far as we are concerned as Westwood said, if it it tns as it enters a property that is what we should treat it as.

There is a difference between tncs (tera neutral combined seperate) and pme (protective multiple earthing). You can have tns and a pme system and that is the difference

 

[Ian1981]

If it’s tncs outside but separate earth entering the property then I’d imagine the dangers or an open circuit neutral in the road will still cause Potential for danger in the installation regarding exposed conductive parts rising to or near mains potential as any tncs installation would.

 

[Marvo]

I think it would be inadvisable to 'assume' the DNO supply to be PME if it appears TNS at the service head. If for some reason the supply is thoroughbred TNS then creating a N-E link anywhere would split the neutral current at best and could result in enormous current through that link in the case of an upstream DNO neutral fault in the future.

 

[mjb]

When I worked for DNO, if it did not have a PME label it was not PME regardless.

 

[Midwest]

When I worked for DNO, if it did not have a PME label it was not PME regardless.

Wot if the labels fallen off?

 

[Rpa07]

Wot if the labels fallen off?

The labels are strong they won’t fall off - Now the seals are another matter!!!

 

[Deleted member 105166]

Not those seal fairies again?