Standard explained
Protective Bonding Explained
Protective bonding connects metallic services and parts to the main earthing terminal so they stay at the same potential — a core shock-protection measure in BS 7671.
Protective bonding connects exposed and extraneous metal parts to the main earthing terminal so that, under fault conditions, they remain at substantially the same potential. This prevents dangerous voltages appearing between metal parts that a person could touch simultaneously.
Two kinds of bonding
- Main protective bonding connects incoming metallic services — such as gas, water and structural steel — to the main earthing terminal.
- Supplementary bonding connects metal parts within a location (historically required in bathrooms, though modern RCD protection can remove the need in some cases).
Why it matters on an EICR
Inspectors frequently find missing or undersized main bonding, especially to gas and water. Because inadequate bonding is a risk under fault conditions, it is commonly coded C2. The conductor must be correctly sized for the installation.
Working with earthing
Bonding and earthing arrangements together form the backbone of shock protection. Neither works properly without the other, which is why both are checked carefully during an EICR.
Related service
Earthing & Bonding
Rectification and improvement of earthing and protective bonding arrangements.
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Standard explained
AFDDs (Arc Fault Detection Devices) Explained
An AFDD detects dangerous arcing faults in wiring — a common cause of electrical fires — and disconnects the circuit. BS 7671 recommends them for certain premises.
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BS 7671 Explained: The Wiring Regulations
BS 7671 — the IET Wiring Regulations — is the national standard for the safety of electrical installations in the UK, currently the 18th Edition.
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Cable Selection and Sizing Explained
Cable selection under BS 7671 balances current-carrying capacity, installation method, grouping, ambient temperature and voltage drop so conductors run safely.
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Distribution Boards and Consumer Units Explained
Distribution boards (and domestic consumer units) house the protective devices that control and protect each circuit — their condition is central to any EICR.
Learn moreThis article provides general guidance and distinguishes legislation, British Standards and good practice. It is not legal advice. Always confirm the specific duties applying to your property and tenure.