A GT1 gas test, often called a GT1 survey or request, obtains information about a property's gas service pipe pressure and capacity. It helps businesses plan extra gas demand or meter installation. A site visit may be needed, but the response is not approval to commission equipment or a guarantee of available capacity. This guide covers arrangements in Great Britain.
When might your business need a GT1 survey?
You may encounter GT1 when taking over premises without a gas meter, replacing equipment or increasing gas demand. For example, a larger heating system or additional catering equipment may need more gas than the existing service can deliver.
Cadent uses the term “Gas Transporter 1” and explains its relevance to premises without a meter. SGN also requires a GT1 request when checking an existing service for an increased load. The trigger is the information your project needs; ask the relevant transporter or supplier which route applies. See Cadent's GT1 guidance and SGN's business GT1 process.
Raise this before fixing installation dates, so your project plan can allow for any further work identified.
What does a GT1 gas test or survey check?
GT1 is a request for technical information, rather than one standard physical test performed identically at every site. The transporter may use its records, arrange a survey or request more details.
Depending on the request and network arrangements, the response can cover:
- Service capacity: the gas demand the service pipe can accommodate.
- Supply pressure: information needed to assess the proposed metering arrangements.
- Emergency control valve details: the size and, where supplied, type of the emergency control valve (ECV).
- Service status: whether a live/dead check is needed or has established that gas is present in the service.
Cadent describes these checks, while SGN's application guidance treats a previous live/dead check as separate information. Confirm what your request includes rather than assuming every GT1 involves every check.
A GT1 response does not replace appliance servicing, installation-pipework testing or the safety checks needed before equipment is used.
Prepare the information before requesting GT1
Use the relevant network's current form and instructions. Gather the following before submitting:
- The site name, full address and postcode.
- The meter point reference number (MPRN), which identifies the gas supply point and may appear on a gas bill.
- A site contact who can arrange access.
- The proposed maximum hourly gas demand, confirmed by your engineer.
- The pressure, capacity and ECV information needed by the project team.
- Any existing connection quotation or live/dead-check reference.
SGN's application guide explains these fields and advises consulting a Gas Safe registered engineer if you do not know the maximum hourly load. Its current GT1 page warns that missing required information can lead to rejection and resubmission.
Use the proposed peak demand, rather than copying annual consumption from a bill. Ask the engineer to confirm the units requested by the form and the gas input requirements of the equipment. If an MPRN cannot be found, ask the supplier or transporter how to identify the service before submitting. Our supply-identifier guide explains where to start and how to distinguish a supply point from the physical meter.
Who handles the request and the work afterwards?
Keep responsibilities clear when speaking to the project team:
| Party | What to discuss |
|---|---|
| Gas transporter or network operator | Service-pipe pressure, capacity and any required service alteration. |
| Gas supplier | Supply arrangements and how to arrange the necessary metering work. |
| Meter asset manager or metering provider | Whether the proposed meter installation suits the confirmed load and pressure. |
| Gas engineer | Equipment demand, installation pipework and commissioning requirements. |
SGN's application guide specifically identifies information that may be needed by the supplier or meter asset manager. Give each party the written response and ask them to confirm their next step. Check the gas engineer's registration and relevant qualifications using the HSE's engineer-checking guidance.
BBA Energy can help coordinate the associated supply-contract and metering enquiries through its business-energy services. The transporter assesses its service information, the metering provider addresses the proposed meter, and the appropriately qualified gas engineer handles the installation and commissioning requirements within their scope.
How should you use the result?
Check that the response relates to the correct site and proposed load. If the existing service is suitable, establish what metering and installation work remains. If it is insufficient, ask the transporter about an alteration or capacity increase before committing to equipment installation.
Treat the response's conditions seriously. SGN states that its capacity information is indicative: it neither confirms gas availability nor reserves capacity in the network.
Ask for the expected response date and clarify any charges before proceeding. Survey arrangements and timescales vary, so keep the GT1 enquiry, any service works and the meter appointment as separate items in your programme. A response to an information request is not confirmation that the site is ready to use gas.