Discuss Very high Ze ...no rcd? in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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Hi again..
Did a Ze reading and almost fell over as the result was 600+ ohms.
I thought I was testing a TCNS system but now I am lost.
There are no rcd's in the entire installation so I cant see it being TT?
The pics show the head with the provided earth henely block
and the supply cable with the 16mm earth lead taped onto it exiting the building.
The cables head into the soil and thats the last I can trace them.
I cannot find an earth rod anywhere??
is this a new TNCS supply installed and never had the earth changed?
any ideas greatly appreciated???
 

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I would say it looks like a TN-S system.
Is that an earth cable from the bottom of the earth block going to the incoming supply cable ??

If it is TN-S, then call supplier as there maybe a fault at their end.
Best regards,
Sav
 
i am glowing from all the stinging nettle!!
Why do you think its TT when there is no 100mA RCD before any CU?
cheers
 
I would say it looks like a TN-S system.
Is that an earth cable from the bottom of the earth block going to the incoming supply cable ??

If it is TN-S, then call supplier as there maybe a fault at their end.
Best regards,
Sav

The supply looks like a typical thin tncs supply. the bottom earth cable is not attached to the supply cable armouring like a typical tns that I know. it just runs alongside it into the soil.. But yes thats the earth supply and I dont know where it comes from?
 
It maybe then a TT supply and somehow the earth cable has become dislodged or snapped off from the rod due to exposure / old age etc .

Are the homes next door TT suply ?? Can you look, just to verify ??

Sav
 
Hi again..
Did a Ze reading and almost fell over as the result was 600+ ohms.
I thought I was testing a TCNS system but now I am lost.
There are no rcd's in the entire installation so I cant see it being TT?
The pics show the head with the provided earth henely block
and the supply cable with the 16mm earth lead taped onto it exiting the building.
The cables head into the soil and thats the last I can trace them.
I cannot find an earth rod anywhere??
is this a new TNCS supply installed and never had the earth changed?
any ideas greatly appreciated???


This is a tn-s service, at some stage the service has been altered, the supply cable is 2 core used for tn-c-s, the seperate 16mm earth is to maintain the tn-s status, this is common practice in service alterations or replacament of lead sheath services after faults, the dno has the reposibility to to repair the earth, no doubt they wiill suggest a change to pme if the installation permits
 
I had similar probs in my house. DNO were great and repaired same day. Also upgraded 60A ---> 100A FOC and fitted contractors isolator :)
 

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