Ze

[Shoeman]

Three years ago my house had a Ze of 0.37ohms, this year on periodic done last week the Ze reading was 42.7ohms, this is more like a TT system.
What could be the cause.
External supplier at fault ?
Any help gratefully accepted.
Thanks
Shoeman

 

[Deleted member 19807]

what earthing system do you think you have?

 

[Engineer54]

Three years ago my house had a Ze of 0.37ohms, this year on periodic done last week the Ze reading was 42.7ohms, this is more like a TT system.
What could be the cause.
External supplier at fault ?
Any help gratefully accepted.
Thanks
Shoeman

What did the electrician that carried your PIR have to say about this high Ze value??
I ask, because as far as i know, it would have been his duty to inform the DNO responsible for your supply. This can be/is a dangerous situation not only for you, but your neighbours too. A reading of this level indicates a joint in the supply cable, or the cable itself is breaking down, depending on what earthing arrangement has been supplied to you by the DNO.

 

[i=p/u]

they woulkd come stick 300mA power breaker in

 

[Deleted member 19807]

as i see it we don't know which reading is correct, the system mat be TT and the first test was done without removing main bonding next door may have had a PME conversion and the bonding was giving a low reading,

It could be a TNS and the sheath has gone,

It could be a PME with a poor joint,

as E54 says what did the tester say about it?

 

[trev]

Without knowing what the earthing arrangement is we are fumbling in the dark guys. Best wait for the OP coming back on that before we think about remedies. As he states this is like a TT system I do think he may have a problem though

 

[Engineer54]

Shoeman, Do you know what type of earthing you have to your premises, or do you need help in identifying your earthing type??

 

[ezzzekiel]

as a pure guess given the info, i would say tt originally tested without being disconnected and picking up parallel paths OR a problem on the dno side a quick call should confirm the earthing arrangement

 

[Shoeman]

fior information TNS

 

[i=p/u]

i did it the other day ring power for earthing arrangment and they said the electrician should no, was an electrician and i said do you not need to provide me with this info, she replied il take you details and get somone to get back to you.. following day

 

[Shoeman]

For information when I moved in and had a new CU fitted it was I believe a TNS system

 

[Deleted member 19807]

than you need to contact the dno and tell them.

 

[topquark]

Assuming the Ze has been measured correctly (properly calibrated meter) then it should be reported to the DNO as a matter of urgency and preferably a temporary RCD fitted for additional protection. I would suggest that contacting another electrician may be a good idea as the that should have been the action taken by the electrician that measured the Ze at that latter level.

 

[Shoeman]

next door have had lots of building work done over the past couple of years including having their property rewired. could be an Issue. My electrician says that 3 years ago his full test showed my installation to be TNS. Will contact supply authority ASAP

 

[trev]

Without wishing to set you off into a panic this is way above the permissible level for a TNS system. In your position I would ring the DNO as it is their earth arrangement that has the problem and it is their legal duty to maintain it. If you have any reason to doubt it you could also get another spark in to verify that the original Ze test was carried out correctly.Whereabouts are you based, I'm sure we would have a member near you who wouldn't charge a great deal for this