What Are Earthing and Bonding? Home Safety Guide

The simple explanation

Earthing helps a fault switch off quickly.

If a fault makes exposed metalwork live, the earthing path allows fault current to flow through a protective conductor rather than relying on a person to become the path. That current should make the appropriate fuse, circuit breaker or RCD disconnect the faulty circuit.

The earthing arrangement is a complete system. Seeing one green-and-yellow conductor does not prove that the path is present, continuous or capable of operating the protective device correctly.

The other half

Protective bonding reduces dangerous differences in voltage.

Metal services entering a building can sometimes introduce a potential from outside the electrical installation. Main protective bonding connects relevant services to the installation’s main earthing terminal so that metal parts which might be touched together are less likely to sit at dangerously different voltages during a fault.

EarthingA route for fault current

Helps the circuit’s protective device disconnect when exposed metalwork becomes live.

Main bondingControls touch voltage

Connects relevant incoming metal services to the main earthing terminal where required.

Supplementary bondingUsed in some locations

Additional local bonding may be present where the installation design and wiring rules require it.

Illustrated examples

Where bonding conductors may be visible.

These examples show the principle, not a position to copy. Pipe material, service arrangement and the installation design determine whether bonding is required and where it should connect.

Metallic water serviceMain protective bonding may connect to the incoming metal installation pipework near its point of entry, before significant branches.

Metallic gas serviceWhere required, the conductor is normally connected on the consumer’s metallic installation pipework—not to removable meter equipment.

Supplementary bondingA local connection may be present in certain locations or older arrangements. Modern RCD-protected installations may meet the rules without it.

Appearance varies: green-and-yellow conductors, labels and clamps are useful clues, but a clamp can be loose, connected in the wrong place or electrically ineffective. Only inspection and testing can confirm the arrangement.

Correct real-world examples

What secure gas and water bonding can look like.

These photographs show correctly secured connections found in real properties. They help homeowners recognise the usual clues, but the precise requirement and connection point still depend on the service material and installation.

Correct water main protective bonding connection near the incoming stop tap — Correct exampleWater protective bondingA secure green-and-yellow conductor and clamp on the hard metal water pipework near the incoming stop tap, before the pipework branches.

Correct gas main protective bonding connection with a BS 951 safety label — Correct exampleGas protective bondingA secure BS 951 clamp on the consumer's hard metal gas pipework with the visible “Safety electrical connection—do not remove” label.

Secure gas protective bonding connection on hard metal pipework at an external meter position — External meter exampleGas bonding after a meter alterationThe conductor is securely clamped to the consumer's hard metal installation pipework. The correct position still depends on where the pipe enters the building and must be confirmed electrically.

Correct-looking does not mean tested. A clamp can appear secure while having poor contact, an unsuitable position or no effective continuity back to the main earthing terminal. Electrical testing is still required.

Genuine SL4 inspection findings

Loose service bonding should never be ignored.

Loose green and yellow gas protective bonding conductor pulled free from its bonding clamp — Real fault · found during an EICRLoose gas protective bonding conductor
The clamp should be securely fitted around the correct metallic pipe and the green-and-yellow conductor should be firmly terminated under its screw. The conductor should never be loose, hanging free or able to pull out.
**Clamp:** should sit firmly around the pipe, with no obvious gap or movement.
**Conductor:** should be securely held at the clamp terminal, not loose or disconnected.
**Look only—do not tug, test or tighten it yourself.** If it is visibly loose or disconnected, leave it alone and arrange for an electrician to secure and electrically test the bonding.

Water protective bonding clamp and conductor completely detached from the metallic water pipe — Real fault · found during an EICRDisconnected water protective bonding
Here the complete clamp assembly has come away from the metallic water pipe. Where bonding is required, a disconnected clamp cannot provide the intended protective connection to the main earthing terminal.
**Clamp:** is no longer secured around the pipe and has no effective metal-to-metal contact.
**Conductor:** has visible copper strands and its condition and termination need checking before reconnection.
**This fault is being demonstrated by an electrician.** Homeowners should never pull a conductor or clamp to see whether it is secure. If one is already loose or detached, do not touch it—arrange inspection, repair and continuity testing.

Real gas and water examples

What loose service bonding can look like.

These short clips show the bonding connections at gas and water services. In both cases the clamp should be secure around the correct metallic pipe and the green-and-yellow conductor should be firmly held at its terminal—not loose or able to pull free.

Real SL4 exampleGas protective bondingThe conductor at the gas service should be securely terminated and must never be left loose or disconnected.

Real SL4 exampleWater protective bondingThe conductor at the metallic water service should be secure at the clamp and should not hang free or pull out.

These checks are demonstrated by an electrician. Homeowners should look only. Never pull, test, tighten, remove or reposition a bonding conductor or clamp. If anything appears loose, leave it alone and arrange an electrical inspection.

A safe visual check

What can a homeowner look for?

Green-and-yellow conductorsThese may be visible near the electricity intake, meter position or incoming metal services.

Clearly secured clampsThe clamp should look firmly fitted around the pipe and the conductor should be held securely under its terminal screw. Do not pull it to check.

No obvious damageReport a loose, cut, heavily corroded or disconnected conductor without touching or trying to repair it.

Installation recordsAn EICR or electrical certificate can record the earthing arrangement and test results.

Do not touch, loosen or move a clamp. Do not open the meter equipment or consumer unit. The correct location, conductor size and electrical continuity need to be checked by a competent electrician using test equipment.

Gas meter alterations

Has your gas meter been moved?

Moving a meter—commonly from inside the property to an outside box—can also change where the gas installation pipe enters the building. The old bonding conductor must not simply be left behind, extended without assessment or reconnected wherever it reaches.

Internal gas meterWhere bonding is required, the connection should be on the consumer's hard metal pipework, before any branch pipework and, where practicable, within 600 mm of the meter outlet union.

External gas meterWhere practicable, the connection should be on the consumer's hard metal pipework at the point where it enters the building, before any branch pipework.

Plastic incoming serviceMetal pipework does not automatically require bonding just because it is metal. An electrician must determine whether it can introduce an outside earth potential.

After the meter moveThe conductor size, route, connection position, clamp, identification and electrical continuity should all be confirmed by an electrically competent person.

A gas installer and electrician may both need to be involved. Gas work must be handled by a Gas Safe registered engineer. Electrical bonding should only be altered and tested by someone competent to carry out that electrical work.

Further readingInstaller Online: bonding when relocating a gas meter ↗

When it should be checked

New electrical work relies on the existing earthing and bonding.

An electrician should confirm the arrangements before carrying out additions or alterations. They are also examined during an EICR, and should be investigated if a conductor appears damaged, a service pipe has been replaced or altered, the property has no reliable electrical records, or anyone has received a shock or tingling sensation.

Authoritative guidanceElectrical Safety First: earthing and bonding ↗IET: earthing and bonding FAQs ↗

Common questions

What homeowners usually ask.

Are earthing and bonding the same thing?

No. Earthing provides a path for fault current so a protective device can disconnect the faulty circuit. Protective bonding connects relevant metal services and parts to reduce dangerous voltage differences that could otherwise be touched at the same time.

Does every metal pipe need a bonding clamp?

No. The correct requirement depends on whether the service or metalwork can introduce a potential into the building, the installation design and the applicable wiring rules. A visual guess is not enough; an electrician can inspect and electrically test the arrangements.

Can I add or move a bonding clamp myself?

Do not loosen, remove or relocate earthing or bonding conductors. Their size, route, connection point and electrical continuity matter. Ask a competent electrician to check or alter them.

Does the bonding need checking when a gas meter is moved?

Yes. Relocating a gas meter can change where the gas installation pipe enters the building and may leave an existing bonding conductor in the wrong place, too short or disconnected. Where bonding is required, an electrically competent person should confirm its location, conductor size, secure termination and continuity after the alteration.