ICT Functional Earthing
The Regs and Practice Papers · C&G 2382-26 · Full course section in Plus
In a comms room or a data centre, does two separate jobs. Protective earthing provides the fault path that lets a device disconnect. gives electronic equipment a low- reference so signals stay clean and interference has somewhere to go. They often share metalwork, and they are never interchangeable — a functional earth is not a safety measure and must never be relied on as one.
Scale changes the approach. A single rack takes a protective conductor; a floor of racks takes a bonding network, and the common and mesh arrangements exist so that every enclosure sits at effectively the same potential across a wide range of frequencies. That is an electromagnetic requirement as much as an electrical one, which is also why power and data containment are kept apart.
The safety issue specific to this equipment is protective conductor . Filters in switch-mode supplies leak current to earth by design, and a rack full of them can add up to a level where a broken protective conductor becomes dangerous. Above the stated thresholds a high-integrity protective conductor arrangement and a warning label are required — the point being that the earth here is carrying current in normal service, not only under fault.
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Common questions
- Can I try ICT Functional Earthing free on this page?
- This guide is free to read, but there is no public quiz specifically for this topic on this page. Browse public practice samples for other subjects, or create an account for the learning path. The full course section requires Plus.
- Where does ICT Functional Earthing sit in the City & Guilds scheme?
- ICT maps to C&G 2382-26. On TradeTraining it lives in the The Regs and Practice Papers section as bite-size lessons with practice questions.
- Do I need ICT Functional Earthing for the 18th Edition exam?
- Yes — the C&G 2382-26 exam is set against the BS 7671, and this topic is part of that ground. The exam is open book, so practising fast navigation to the right regulation matters as much as recall.
- What is the difference between functional and protective earthing?
- Protective exists for safety: it provides the fault path that lets a protective device disconnect. Functional earthing exists so equipment operates properly — a signal reference. A functional earth never substitutes for a protective one.
- Why does high protective conductor current need special treatment?
- Because equipment filters leak to earth continuously, so the protective conductor carries current in normal service. If it were to break, that current has to go somewhere — hence a duplicated or enhanced protective conductor arrangement and a warning label.
Explore key terms
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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.
Read the full Functional earthing glossary entryEarthing
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 full Earthing glossary entryCPCCircuit Protective Conductor
The earth wire of a circuit. It links the metal parts of the equipment the circuit feeds back to the main earthing terminal. Normally it carries no current; if a fault makes that metalwork live, it carries the fault current so the fuse or breaker switches off. In UK wiring it is green and yellow, or bare inside twin-and-earth cable, with green-and-yellow sleeving wherever it is exposed.
Read the full CPC glossary entryMain protective bonding
Conductors connecting incoming metallic services — water, gas, oil, structural steel — to the main earthing terminal. Bonding does not clear faults; it holds the touchable metalwork of a building at roughly the same potential while a fault lasts, so a person touching a pipe and an appliance at the same moment isn't bridging a dangerous voltage difference.
Read the full Main protective bonding glossary entry