Missing gas bonding marked C2 on an EICR

A C2 for missing or ineffective main protective bonding to the gas installation makes the EICR unsatisfactory. The inspector has concluded that, in the context found, the absence or ineffectiveness of bonding could create a potentially dangerous difference in voltage under fault conditions. Urgent remedial action is required.

That does not mean every report mentioning gas bonding is automatically C2. The inspector must establish that the gas service or associated metalwork can introduce earth potential, that bonding is required for the installation, and that the connection is absent, not visible, or tested and found ineffective. Plastic incoming services, meter arrangements and altered pipework can change the assessment.

This page focuses on the narrow gas-bonding C2 observation. For wider bonding context, see the general missing-bonding guide. Classification principles for C1, C2, C3 and FI are explained in the dedicated codes hub.

Main protective bonding to gas connects relevant extraneous-conductive-parts of the gas installation to the main earthing terminal. Its purpose is to hold simultaneously accessible metalwork at a more nearly equal potential while the protective system operates, reducing shock risk if an electrical fault energises pipework or associated metal.

Bonding is not primarily installed so that gas pipes carry fault current back to the supply. Earthing, circuit protective conductors and automatic disconnection provide related but distinct parts of the fault-protection arrangement. A missing gas bond can become more significant when combined with poor earthing, accessible Class I equipment near the service, or shared metallic services in converted buildings.

Because the protective measure works as a system, the EICR observation should describe the conductive part, location, evidence and classification — not rely on a generic label such as “no gas bond”.

BS 7671 defines an extraneous-conductive-part by its ability to introduce a potential, generally earth potential, and by it not forming part of the electrical installation. A metal gas service entering the premises may meet that definition, but material, continuity to earth and the point of entry must be established on site.

A short metal section fed entirely through an insulating incoming service may not introduce earth potential and may not require main bonding at that location. Conversely, a service that appears plastic at the meter may transition to metal elsewhere. Visual appearance at one convenient point is not always conclusive.

Competent assessment can involve inspection, enquiries and appropriate resistance testing under safely controlled conditions. Clients should not bridge pipes with wire or use a multimeter as a DIY test. Incorrect temporary connections can create hazards and produce misleading results.

The supply characteristics and schedule of inspections record the earthing arrangement and the presence and adequacy of protective bonding. A numbered observation should identify the gas service or conductive part, location, evidence and classification. Where possible, it should distinguish “not visible” from “tested and found ineffective”.

Conductor size, route, termination and continuity may all matter. A clamp can be present but loose, corroded, attached to an unsuitable section, disconnected after gas work or linked by a conductor that does not reach the main earthing terminal. A label alone proves little.

Read companion observations. Missing main earthing, high Ze, an unsuitable earthing arrangement or poor circuit protective conductor continuity can change the risk picture. The code belongs to the observed combination described by the inspector.

C2 is commonly considered where required main protective bonding to the gas installation is confirmed absent or ineffective and the resulting touch-voltage risk is potentially dangerous. It is the safety consequence — not merely non-compliance with a conductor-size table — that supports the classification.

C3 may be appropriate for an improvement that does not amount to potential danger, such as some legacy sizing or labelling issues where the protective measure remains effective. That is only an example of reasoning; conductor material, size, supply arrangement and current requirements must be checked.

FI can be justified where an important gas service route disappears behind finishes, continuity cannot be established and a potentially dangerous omission remains plausible. FI must state what needs investigating. Under the current A4:2026 EICR format, that observation is advisory and does not by itself make the overall EICR unsatisfactory. It should not be used merely because the inspector did not look at an accessible meter area.

• Whether the gas service or part can introduce earth potential and is therefore truly extraneous.
• The earthing arrangement and the condition of the main earthing terminal and conductor.
• Continuity, size and termination of any existing bonding conductor to the gas installation.
• The location of the connection relative to the service entry, meter, branches and insulating sections.
• Accessible Class I equipment and conductive parts that could be touched simultaneously.
• Alterations to gas, heating or meter installations since the electrical installation was last inspected.
• Access limitations caused by boxing, locked intake rooms, fitted kitchens or communal service routes.

A Victorian conversion may have one incoming metal gas service that branches to several flats, with meters in different areas. The electrician must determine each installation's origin and the shared-service arrangement. Adding a clamp beside one flat's cooker may not provide main protective bonding for that installation.

A refurbished flat may have a plastic incoming gas main but metal distribution internally. If testing confirms the internal pipework does not introduce earth potential, installing main bonding simply because metal is visible may be unnecessary. Water, heating and communal services still require separate assessment.

In a purpose-built block, district-heating pipework or structural steel may cross demise boundaries. Responsibility for access and work can involve the freeholder or managing agent, but the EICR still has to record a safety-significant finding. Ownership affects coordination, not classification.

“Every gas pipe needs a green-and-yellow wire” is not technically accurate. The requirement concerns extraneous-conductive-parts, and each service must be assessed. Random cross-bonding of internal pipework is not a substitute for a correctly designed main bonding connection at the appropriate point.

“A visible clamp means the gas bonding passes” is also false. The conductor may be too small, poorly terminated, broken or connected to the wrong earthing terminal. Inspection and testing establish effectiveness.

“Gas bonding C2 always means the whole gas installation is dangerous” overstates the report. C2 means the described condition was judged potentially dangerous in context. The observation text and any test results explain what was found and what remedial work should address.

Where bonding to the gas installation is required and absent, an electrician designs a conductor route and connection suitable for the earthing arrangement and service. The connection is generally made as near as practicable to the point where the service enters the premises, taking account of meters, insulating sections and branches under the applicable requirements.

The work may require access behind removable panels, agreement with a building manager or coordination around gas-meter areas. Electricians must respect supplier equipment and should not attach conductors indiscriminately to flexible connectors, painted surfaces or inaccessible locations. Gas work may require a Gas Safe registered engineer where the scope crosses into the gas installation.

After installation or repair, the contractor verifies continuity and the wider protective arrangement and issues documentation appropriate to the work. A decorative clamp fitted without a proven route to the main earthing terminal does not close the EICR observation.

Send the gas-bonding observation and relevant schedules to ask for a bonding investigation or repair quotation before work is agreed.

Where the report requires further investigative or remedial work, regulation 3(4) can require a qualified person to do that work within 28 days, or any shorter period the report states, starting with the inspection and test. Regulation 3(2A) and 3(6A) also record a reasonable-steps position, including where a tenant prevents entry. That qualification is not a reason to leave a dangerous condition in use, and the code on your report still has to be read with the observation.

Send the complete report to the remedial contractor and identify the exact observation numbers. Ask whether access is needed to communal intakes, service entries or neighbouring demises. Early coordination matters in converted buildings because a technically simple conductor route can become an access problem.

Keep the original EICR, quotation, access correspondence and completion evidence. London EICR Certificates can help coordinate inspection and remedial appointments; the assigned code and report evidence determine what work is required — not a generic checklist.

Ask the inspector which gas-related conductive part requires bonding, how they established that it is extraneous, whether a conductor was absent or merely not visible, and what earthing arrangement and test evidence informed the C2. If FI was used, request a precise scope for the follow-up investigation.

Do not fit clamps, run temporary wire or disconnect existing green-and-yellow conductors yourself. Bonding interacts with the installation's fault-protection system, and services can be shared or unexpectedly energised during faults. A competent electrician should isolate, inspect, test and design the correction.

If anyone experiences tingling or shocks from pipework, appliances or gas fittings, stop using the affected equipment and seek urgent professional help. Heat, arcing or damaged intake equipment also calls for an immediate safety response using the appropriate emergency route.

Sources checked on 3 October 2026. Read this guidance alongside your own EICR: its edition, observations, extent and limitations matter. Ask a qualified electrician to assess the findings at your property.

Building services, wiring arrangements and access differ substantially across London property types. The examples explain why judgement varies; they do not prescribe a code remotely. Current standards, reliable test evidence and the competent person's assessment of the actual installation determine whether gas bonding is required and how an observation is classified.

This article was editorially reviewed on 2026-10-03. It provides general operational guidance for London property decision-makers and is not personalised legal advice.

Electrical classification on an EICR depends on the installation, the observations recorded and competent professional judgement. Always read your own report and seek competent advice for your property.