High impedence Zs readings at consumer unit and sockets

pieroabcd

Hi,
I've just received my EICR where everything is green except this FI row that reads "High Zs readings at consumer unit and sockets"
Is it mandatory to correct?
They quotes me 360 for supposed 3 hours of work for a further investigation after which they will recommend a suitable solution.

The only Zs values that I can see in the report are in the sockets. They range from 8.99 to 9.28.
In 2011 they were 0.3 - 0.4. I imagine that these values don't naturally change over time.

The report was cheap, 80 pounds, but how can I make sure that I can trust what they are telling me?

Ectophile

An earth resistance around 9 ohms is far higher than it should be.  It should only be a fraction of an ohm.  If there's ever a short between live and earth somewhere in the system, then it may never trip a breaker and could start a fire or electrocute someone instead.

Code 1 faults are in the "get it fixed before it kills somebody" category.

pieroabcd

Tomorrow there's the follow up

pieroabcd

The doubt is: how are they going to fix it and how much is it likely to cost?

pieroabcd

According to the guy that came today the impedence is too high already at the entry point in my house, where there's the connection between the ground system coming from the network operator, so it's competence of the DNO.

I've saved some money in some useless checks, but they could have measured this impedence from the start and let me save 120 pounds.

Ectophile

Contact the DNO.  They should fix it for free as an emergency call.

gm0

I had a similar scenario with some socket changes which would not pass modern checks. 
30 year old installation late 90s.

DNO came for free and bonded the earth / neutral arrangements correctly.
Domestic Sparky retested and signed off their socket work and completed the job.

With local network (PME) if it is that to your house as it was with mine then the electrical distance to the next place in the streets and poles  where it is N to E bonded was too far.

Many properties of similar and older vintage and rural (PME) were commissioned without the supply fuse earth bond present in the house.  With the earthing in the area at the time, and the rules that applied at the time; the DNO were not that bothered about it.  They still don't go hunting for them.  When someone makes a change, does a test and finds it - they fix it to the modern rules. 

If the problem persists with this item fixed - you will have to dig deeper on the house wiring.