Earthing and bonding explained
Earthing and bonding are what make a fault safe. Missing bonding is one of the most common C2 findings.
Earthing
The earthing system gives fault current a low-resistance path back to the source, so the protective device trips quickly. UK homes are usually supplied with TN-C-S (PME), TN-S or TT earthing. The type is recorded on the front of your EICR.
Main protective bonding
Metal gas and water pipes entering the property are connected to the main earthing terminal with green and yellow conductors, usually 10 mm² in homes. This keeps all exposed metal at the same potential, so a fault cannot create a dangerous voltage between a tap and a radiator.
Supplementary bonding
Older bathrooms often have extra bonding between pipes and metalwork. Under current regulations it can be omitted if the bathroom circuits have RCD protection and the main bonding is in place.
Fixing missing bonding
Usually a short job: a new conductor and earth clamp at each service entry, labelled and tested. It is often done the same day as the inspection if you approve it.
Questions
Plastic pipes: do they need bonding?
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