MET1 is about the meter installation itself: location, the ECV, regulator, seals, labels and leaving the installation safe.
Every downstream gas job depends on the meter installation being right, which is why MET1 rewards precise knowledge of a small number of components: the emergency control valve, the regulator and its seal, the meter itself, its location and the labels that let a stranger make the installation safe in an emergency.
What MET1 covers
Domestic-sized meter installations: diaphragm meters such as the U6 and G4, electronic and smart equivalents such as the E6, meter boxes and compartments, regulators, the emergency control valve and the connections around them. The module tests whether you can install, exchange, check and leave a meter installation safe — and whether you recognise when someone else has left one unsafe.
Gas meter capacity, gas rate and working pressure
A meter designation such as U6 describes a capacity class; confirm the actual rated flow from its technical information. It is not the volume currently passing through the meter or the internal volume used in a tightness-test assessment. The gas rate calculation measures volume per time, while pipe sizing checks whether a proposed route can supply its stated demand.
Working pressure is measured with gas flowing under the specified load. Standing pressure is measured without that flow. Record the test point and operating condition: an acceptable standing reading does not prove acceptable meter-outlet or appliance-inlet working pressure under demand.
Locations, boxes and compartments
- External meter boxes: purpose-made, protected from damage, with the box vented as designed — and never sealed up to keep draughts out.
- Internal locations: accessible, ventilated where required, away from heat and ignition sources, and not in a position that traps escaping gas.
- Compartments and cupboards follow the same principle: a meter must be reachable, readable and safe to work on.
- Protection matters: a meter where cars park, or under a likely impact point, is a siting question before it is anything else.
The emergency control valve
The ECV is the consumer’s means of shutting off the gas in an emergency, so the revision points are all about usability: it must be accessible without tools or keys hidden elsewhere, its handle fitted so the off position is obvious and reached with a simple movement, and it should be labelled with emergency instructions so a member of the public can act. An ECV buried behind boxing, painted solid or missing its label turns up constantly in unsafe-situations questions.
Regulators and seals
The regulator controls downstream pressure within its operating conditions. Check the correct equipment, installation and required seals. A seal indicates interference protection; its presence does not prove correct pressure performance or rule out tampering. Damage, missing seals or suspected interference need the responsible meter operator’s reporting route, not an improvised adjustment or replacement seal.
Bonding and connections
First establish whether main protective bonding is required for the installation. Where it is, its location depends on the pipe’s entry into the premises and whether the meter is inside or outside. Do not apply “600 mm from the meter” to every arrangement without those conditions. The connection, conductor and accessibility must meet the electrical requirements and any relevant pipe-system instructions.
An insulating service section does not prove that all other connections to Earth are absent. Keep main protective bonding separate from temporary continuity precautions during gas work. Use the MET1 revision notes to work through the arrangements; electrical assessment or remedial work needs the relevant competence.
Testing, labels and leaving safe
- Work on the meter installation ends with a tightness test and, where gas has been introduced or displaced, correct purging before appliances are relit.
- Labels and notices: the ECV emergency notice and the meter installation information a stranger would need.
- Smart meters change the technology, not the duties — location, ECV, sealing and tightness principles still apply.
- Record what you did and leave the installation so the next engineer can prove it safe quickly.
Common exam traps
- Treating the ECV and the meter outlet valve as interchangeable in scenario answers.
- Confusing the gas supplier, network operator and meter operator when reporting a defect — establish who is responsible for the affected equipment.
- Missing the bonding check after meter work.
- Accepting an unventilated, sealed-up meter box because the customer prefers it tidy.
- Quoting a pressure figure without saying where it is measured and under what condition.
Quick answers
What is the ECV on a gas meter?
The emergency control valve — the consumer’s shut-off for the whole installation. It must be accessible, clearly operable to its off position and labelled with emergency instructions.
Who owns the gas meter and regulator?
Do not assume that the supplier, network operator and meter owner are the same organisation. Establish the responsible party for the equipment and use their reporting route; a householder can start with their gas supplier for a meter problem. Suspected escaping gas needs the emergency route, not a routine meter enquiry.
Where does main bonding connect near a gas meter?
Where main protective bonding is required, assess the meter position, the installation pipework and its point of entry. Internal and external meters need different location checks, so a bare “600 mm from the meter” answer is incomplete. Follow the current electrical requirements and pipe-system instructions, with competent assessment of the installation.
Why do you purge after working on a meter or pipework?
Purging controls the displacement of air by gas when commissioning, or gas by another medium when taking pipework out of service. The transition can contain a flammable mixture. The applicable procedure determines whether direct purging is suitable, how discharge is controlled and how completion is confirmed; elapsed time or the disappearance of a smell is not a substitute.
Can a U6 gas meter label determine the tightness-test allowance?
No. Meter flow capacity and installation volume are different quantities. The relevant procedure considers the fuel, work scope, appliance condition and any required volume assessment. A capacity badge alone cannot establish a permissible pressure loss or a passed test.
Where can a gas meter be located?
The reasoning is access, separation and protection, in that order. The meter and above all the emergency control valve have to be reachable so the supply can be shut off quickly, read and maintained. Meters are kept clear of heat sources and of electrical equipment and cabling with suitable separation. The enclosure matters too: a box or compartment must be suitable and, where required, ventilated, and the meter protected against damage and corrosion — damp, unventilated or cramped positions are poor choices. Some positions are restricted or need extra precautions, escape routes among them.
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