Earthing — inspection and repair
Earth electrode resistance measured with a calibrated instrument and written up — and put right when the result calls for it.
Earthing is the protection nobody notices while it works, and nobody notices has stopped working — until it shocks somebody.
What we measure
Earth electrode resistance — whether the electrode in the ground is still doing anything.
Earth fault loop impedance — whether the protection will disconnect fast enough when a fault reaches an appliance body.
Protective conductor continuity per circuit — whether the wire is broken somewhere or never connected at all. This is the most common finding in flats where somebody has "tidied up" the installation.
All with a calibrated instrument. The result is a record with numbers, not an estimate.
Three states we find
The wire is there and connected to nothing. Classic in flats where a third wire was added later, reached the first junction box and stopped.
Connected, but the joint has corroded. Measured resistance is high; protection works more slowly than it should, or not at all.
Everything connected, but the electrode is finished. In older houses, where the tape in the ground lost contact long ago.
Why this is not a formality
In an installation without sound earthing, an RCD will not respond to a fault on an appliance body until somebody touches it. The device is there, it looks like protection, and it protects nothing. That is why earthing gets measured before any other conclusion is drawn about an installation's safety.
There is more on the symptoms in the article on recognising poor grounding.
Do not put it off
If something has already given you a shock at the sink or the tap, do not put it off — the measurement is one visit and gets done the same day.
Common questions
How do I know my earthing is not good?
The clearest sign is a shock from a tap, a sink or an appliance body — that means leakage current has nowhere to go except through you. Milder signs are hum in audio equipment and appliances failing for no obvious reason.
Why measure earthing, surely you can see whether the wire is there?
A wire being there does not mean it is connected, nor that the joint in the box is still sound, nor that the electrode resistance is low enough. All three are only proven by measurement.
Can earthing be taken from a water pipe?
No. It used to be common practice and is no longer permitted — one neighbour replacing a section with plastic pipe and your earth is gone with no visible sign.
What does it cost?
Measurement with a written record is one visit. The repair depends on the findings: re-terminating in the board and junction boxes is usually half a day, while a new electrode is groundwork and another order of magnitude. That is why we measure first.