Functional earthing
An earth connection made because equipment needs it to work — a clean signal reference for ICT and electronic systems — rather than for shock protection. It matters now because Amendment 4:2026 of BS 7671 updated the requirements around functional earthing for information and communication technology installations.
Where Functional earthing fits in the learning path
The Installation section covers these units:
- Wiring Systems & Enclosures
- Cable Selection & Circuit Design
- Earthing, Bonding & Consumer Units
Curriculum mapping: C&G 2365 Units 203/204/305.
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This section is on the Plus path. Lesson availability depends on content review and your learning path.
Read, practise, return
1. Read it in context
- BS 7671 Amendment 4The Regs and Practice Papers
2. Try recalling, then explore practice
Use the memory prompt below to connect the vocabulary.
- 18th Edition Exam — quiz previewPlus · The Regs and Practice Papers
3. Return to the meaning
After reading or practising, explain the idea in your own words. Revisit the Functional earthing definition to check what you remembered.
Recall a related term
Which term fits this definition? Say it to yourself, then reveal it. This is a memory prompt, with no score or saved result.
Connecting an installation's exposed metalwork to earth and back to the supply source. That gives fault current a deliberate low-impedance path home, turning a live casing into a large, brief fault current that the protective device can detect and disconnect — without it, the casing simply stays live.
Earthing
Read the Earthing entryCompare related terms
Open a meaning to compare its role with Functional earthing, or follow its full entry.
Earthing
Connecting an installation's exposed metalwork to earth and back to the supply source. That gives fault current a deliberate low-impedance path home, turning a live casing into a large, brief fault current that the protective device can detect and disconnect — without it, the casing simply stays live.
Read the Earthing entrySPD — Surge Protective Device
A device that diverts brief, high-voltage spikes — from lightning activity or heavy switching — safely to earth before they reach sensitive equipment. Usually fitted at or near the consumer unit, SPDs have moved from a luxury to an expected part of new installations as homes fill with vulnerable electronics.
Read the SPD entryPELV — Protective Extra-Low Voltage
An extra-low-voltage system fed from a safety source like SELV, but with one point deliberately connected to earth. The earthed reference suits control circuits and electronics that need it, at the cost of losing SELV's complete separation — the difference between the two is a reliable exam question.
Read the PELV entryA definition is a start. Using it in a real question is where it sticks.