Help with a 21ohm Ze

[whatever]

Hi all I'm new to this forum so maybe this situation isn't unusual but I have just done an EICR ( I've not done many) on a one bedroom vacant flat. All checks out ok in the flat and the RCD trip times are well within limits but at the incoming TNS supply with a 25 mm earth clamped to the armour sheath I get a Ze of 21ohms so naturally none of the circuits comply with max Zs values. Is it the DNOs responsibility to fix this because surely I can issue a Satisfactory EICR!

 

[stevethesparks]

What have you put in the "Earthing arrangement" tick box

 

[whatever]

What have you put in the "Earthing arrangement" tick box

Nothing yet, but I don't understand the reason for your Q, please explain.

 

[Darkwood]

It is not as uncommon as you may think, armour breakdown along the route or at a junction is possibly why the earth is high, legally if it still is the same the DNO do not have to supply an earth and it is down to the electrician to provide a suitable earth when needed, however given this was the failure of an existing earth already provided I would be notifying the DNO about the situation.
Your part in from here changes, you need to ensure that the installation is not unsafe and RCD operation is not to be relied on here, you may have to rod the property on a temp' or permanent basis depending on what the DNO decides to do, the last few occasions I have come across this they had to convert the street to TNC or PME.

I haven't done domestic for 20yrs so others more up to date may say different and it may even be regionally different but the common factor here is you don't leave a unsafe installation and a minimum you take measures to make it safe if you intend to leave it energised.

 

[Wilko]

Hi - it sounds like a fault with the earthing arrangement which is reported in Item 1.2 of the Report. My 20p worth is - with the importance of earthing to electrical safety this would not be a satisfactory report, regardless of who might fix the fault.

 

[whatever]

It is not as uncommon as you may think, armour breakdown along the route or at a junction is possibly why the earth is high, legally if it still is the same the DNO do not have to supply an earth and it is down to the electrician to provide a suitable earth when needed, however given this was the failure of an existing earth already provided I would be notifying the DNO about the situation.
Your part in from here changes, you need to ensure that the installation is not unsafe and RCD operation is not to be relied on here, you may have to rod the property on a temp' or permanent basis depending on what the DNO decides to do, the last few occasions I have come across this they had to convert the street to TNC or PME.

I haven't done domestic for 20yrs so others more up to date may say different and it may even be regionally different but the common factor here is you don't leave a unsafe installation and a minimum you take measures to make it safe if you intend to leave it energised.

Thanks for the reply, It's a third floor flat no garden in Central London. I can't see the neighbours in the basement being to happy with an earth rod in the middle of the sitting room?

 

[whatever]

Hi - it sounds like a fault with the earthing arrangement which is reported in Item 1.2 of the Report. My 20p worth is - with the importance of earthing to electrical safety this would not be a satisfactory report, regardless of who might fix the fault.

Ah, okay thanks

 

[DPG]

Thanks for the reply, It's a third floor flat no garden in Central London. I can't see the neighbours in the basement being to happy with an earth rod in the middle of the sitting room?

Plant pot full of soil on the balcony? ?

 

[whatever]

Plant pot full of soil on the balcony? ?

Not a rubber plant though, resistance is too high already?

 

[Darkwood]

If this is a 3rd floor flat then is it DNO issue or a sub mains on consumer/landlord side, I am not too ofay with how they arrange supplies in multi occupancy buildings in London. Do you have a cutout in the flat itself?

 

[telectrix]

3rd floorflat could have a perfectly good Ze at intake but then fed to flat in SWA which maybe incorrectly terminated ( i.e. armour not connecting with supply earth.)in which case it's the sparky's responsibility.not DNO's.

 

[stevethesparks]

I understood the test to be a ZE, I would indicate any further testing out in the field as Zdb

 

[telectrix]

I understood the test to be a ZE, I would indicate any further testing out in the field as Zdb

that's whati mean good Ze but a bad Zdb. could be a ryefield in the basement.

 

[loz2754]

On the matter of the DNO responsibility, I believe that they're not obligated to provide an earth, but where they do, they're obligated to maintain it.

 

[whatever]

3rd floorflat could have a perfectly good Ze at intake but then fed to flat in SWA which maybe incorrectly terminated ( i.e. armour not connecting with supply earth.)in which case it's the sparky's responsibility.not DNO's.

There is a Distribution board on the ground floor where the suppliers feed comes in, 3 phase and earth, that's where I measured the reading, that is a direct Ze reading of the suppliers cable where it enters the building so I figure the other two flats in the building will also have the same problem.