ACS MET1 Domestic Gas Meters (Gas Safe, UK)

Under the Gas Safety (Installation and Use) Regulations 1998 (GSIUR) Regulation 3, what qualification must an engineer hold before installing, exchanging, or commissioning a domestic gas meter in the UK?

• AA valid Gas Safe Registration covering Core Domestic Natural Gas Safety (CCN1) and the ME…
• BAn unrestricted NVQ Level 2 in Plumbing and Domestic Heating without Gas Safe registration
• CA local authority building control registration card for electrical and gas services
• DA manufacturer product certificate for the specific electronic meter model being fitted

What is the maximum badged gas flow capacity for a domestic meter covered under the scope of the ACS MET1 module?

• AUp to and including 6 m³/h (e.g. U6 / E6 meters)
• BUp to 16 m³/h (e.g. U16 commercial meters)
• CUp to 40 m³/h (e.g. U40 industrial diaphragm meters)
• DUnlimited capacity provided the inlet pressure is below 75 mbar

What is the primary function of an Emergency Control Valve (ECV) installed on a domestic gas meter installation?

• ATo allow the consumer or emergency operative to shut off the gas supply to the installati…
• BTo automatically regulate the gas pressure down from medium pressure to 20 mbar working p…
• CTo measure the volume of gas consumed by downstream appliances for billing
• DTo prevent back-siphonage of water into the gas service pipework

According to BS 7671 and GSIUR Regulation 18, where must the main protective equipotential bonding connection be made on a domestic gas installation?

• AOn the consumer's hard metal pipework within 600 mm of the meter outlet connection, befor…
• BOn the flexible corrugated meter connector on the inlet side of the governor
• COn the emergency control valve handle inside the external meter box
• DAt the gas appliance burner manifold inside the boiler casing

What minimum copper conductor cross-sectional area is required for main protective equipotential bonding under BS 7671 for a standard domestic gas installation?

• A10 mm²
• B4 mm²
• C2.5 mm²
• D16 mm²

What is the standard test pressure used when conducting a tightness test on a low-pressure natural gas domestic installation with a U6 meter per IGEM/UP/1B?

• A20 mbar
• B50 mbar
• C100 mbar
• D10 mbar

What is the required stabilization period before commencing the 2-minute timed tightness test under IGEM/UP/1B?

• A1 minute
• B5 minutes
• C10 minutes
• D30 seconds

During a tightness test on an existing domestic installation with appliances connected and a calculated Installation Volume (IV) of 0.008 m³, what is the maximum permissible pressure drop over the 2-minute test under IGEM/UP/1B Edition 4 (natural gas) if NO gas smell is detected?

• A4 mbar
• B0 mbar
• C8 mbar
• D1 mbar

What is the purpose of conducting a let-by test on the Emergency Control Valve (ECV) prior to performing a main tightness test?

• ATo verify that the ECV shuts off gas completely and does not leak gas past the valve seat…
• BTo check whether the meter index clock mechanism is recording gas flow accurately
• CTo measure the maximum peak demand flow rate of the property
• DTo test whether the main equipotential bonding cable carries stray electrical current

What is the nominal standing pressure expected at the test point of a low-pressure domestic natural gas meter when all appliances are turned off?

• A20 mbar (acceptable range 18.5 mbar to 21.5 mbar)
• B37 mbar
• C75 mbar
• D5 mbar

When measuring the working pressure at the outlet test point of a domestic U6 meter with all connected appliances running on full rate, what is the minimum acceptable working pressure?

• A19 mbar (with a nominal 20 mbar regulator setting)
• B12 mbar
• C25 mbar
• D30 mbar

Under the Gas Industry Unsafe Situations Procedure (GIUSP / IGEM/G/11), how is an installation classified if it exhibits a defect that presents an immediate danger to life or property?

• AImmediately Dangerous (ID)
• BAt Risk (AR)
• CNot to Current Standards (NCS)
• DAdvisory Notice (AN)

If a gas engineer encounters an Immediately Dangerous (ID) gas meter installation and the customer refuses permission to isolate the supply, what immediate action must the engineer take under GIUSP?

• AContact the Gas Emergency Service Provider (0800 111 999) to request emergency entry/isol…
• BLeave the premises without taking further action as customer refusal absolves the engineer
• CCall the police non-emergency line and wait outside until a warrant is issued
• DCap the internal pipework without touching the Emergency Control Valve

What is the minimum clearance required between a domestic gas meter installation and electrical equipment (such as electricity meters, consumer units, or switches) under BS 6400-1 unless a fire-retardant partition is fitted?

• A150 mm
• B25 mm
• C500 mm
• D1000 mm

An operative is calculating the gas rate of a domestic boiler using a digital metric ultrasonic gas meter (E6). Over a 2-minute test period, the meter index advances by 0.080 m³. Given a gross calorific value of 39.5 MJ/m³, what is the gross heat input rating of the appliance?

• A26.3 kW
• B15.8 kW
• C31.6 kW
• D10.5 kW

When purging a domestic gas meter and installation pipework after exchanging a meter per IGEM/UP/1B, what volume of gas must be purged through to atmosphere to ensure air is completely evacuated?

• AAt least 1.5 times the total volume of the meter and installation pipework, or until 100%…
• BExactly 0.001 m³ regardless of pipe length
• CThree full purges lasting 10 seconds each
• D10 times the volume of the meter case only

What type of pipework material is prohibited for constructing internal domestic gas meter connections and installation pipework under GSIUR?

• ALead pipework and unapproved plastic pipework inside buildings
• BCopper pipework with capillary solder fittings
• CMild steel pipework with threaded connections
• DPEX-AL-PEX multilayer pipework with manufacturer-approved gas press fittings

What is a 'secondary meter' (sub-meter) in a gas installation?

• AA meter installed downstream of a primary meter to measure gas consumption for a specific…
• BThe backup emergency meter installed by the Gas Emergency Service Provider during network…
• CAn electronic display unit fitted inside the kitchen that mirrors the outside meter index
• DA high-pressure gas meter fitted upstream of the main network regulator

According to GSIUR Regulation 14, what label must be affixed near the primary meter or Emergency Control Valve?

• AA notice detailing the procedure to isolate the supply in an emergency, emergency contact…
• BA warning label stating that gas appliances must be serviced every 3 months
• CAn electrical safety certificate issued by the National Inspection Council for Electrical…
• DA diagram showing all internal appliance flue termination points across the building

When connecting a main protective bonding conductor to a domestic gas pipe using a BS 951 clamp, what label must be permanently attached adjacent to the clamp?

• ASafety Electrical Connection — Do Not Remove
• BGas Safety Warning — High Voltage
• CProperty of Gas Safe Register
• DEmergency Isolation Switch

What is the purpose of the meter governor (regulator) fitted on a domestic gas meter installation?

• ATo reduce varying network inlet pressures to a constant, safe outlet working pressure of…
• BTo shut off gas automatically if the consumer exceeds their monthly gas credit allowance
• CTo filter solid debris and dust out of the gas stream before it enters the meter index
• DTo mix air with natural gas to maintain correct stoichiometric air-fuel ratio

If a let-by test shows a pressure rise from 10 mbar to 15 mbar over 1 minute with the ECV closed, what does this indicate?

• AThe Emergency Control Valve is letting gas by (passing gas across its seat) and must be r…
• BThe installation pipework has a major leak to atmosphere
• CThe meter regulator is venting gas correctly through its relief valve
• DThe test gauge is faulty and must be recalibrated

What action should be taken under GIUSP if an operative discovers an installation with a defect classified as 'At Risk' (AR), such as an unvented gas meter compartment with inadequate ventilation area?

• AWith customer consent, turn off and isolate the affected installation/appliance, apply an…
• BImmediately disconnect the gas service pipe at the main roadway valve without informing t…
• CClassify as Immediately Dangerous and call emergency services to evacuate the building
• DVerbally inform the occupant but leave the installation operating without documentation

Under BS 6400-1, what is the requirement for ventilation in a purpose-built external meter box housing a U6 gas meter?

• ABuilt-in vents providing a minimum free area at high and low levels to prevent gas accumu…
• BComplete hermetic sealing with zero airflow to keep out moisture
• CForced mechanical extraction fan connected to the electricity meter circuit
• DVentilation louvres located only on the bottom floor of the box

An installation has a U6 meter and 15 metres of 22 mm copper pipework (volume approximately 0.005 m³). The meter case volume is 0.008 m³. What is the minimum purge volume required under IGEM/UP/1B?

• A0.0195 m³ (1.5 × 0.013 m³)
• B0.008 m³
• C0.050 m³
• D0.005 m³

What is the maximum allowable pressure drop across a domestic gas meter (from inlet test point to outlet test point) at full badged capacity (6 m³/h) under BS 6400-1?

• A1.0 mbar
• B5.0 mbar
• C10.0 mbar
• D0.1 mbar

Why must a temporary continuity bond (jump lead) be fitted across the pipe joints BEFORE removing or disconnecting a gas meter?

• ATo prevent electrical sparking caused by stray circulating currents or PME neutral curren…
• BTo maintain gas pressure in the downstream pipework during exchange
• CTo ground static electricity from plastic meter index covers
• DTo calibrate the electronic pulse output module of the new meter

What is the GIUSP classification for an installation where a gas meter is found installed in a location with no ventilation and directly adjacent to an uninsulated heat source exceeding 60°C?

• AAt Risk (AR)
• BNot to Current Standards (NCS)
• CImmediately Dangerous (ID)
• DFully Compliant

Under GSIUR Regulation 25, what must an operative do upon completing the installation of a new domestic gas meter?

• ATest the installation for tightness, purge air from the system, verify operating pressure…
• BLeave the main Emergency Control Valve locked off until the local authority inspects the…
• CPerform a hydraulic pressure test at 6 bar on the gas service pipework
• DHand the customer an uncompleted blank warning notice

Which standard specifies the technical installation requirements for domestic gas meters operating up to 6 m³/h at low pressure in the UK?

• ABS 6400-1
• BBS 7671
• CBS 5440-2
• DBS 5839

What is the primary risk of attempting to purge a gas meter installation directly into an enclosed room without using a purge hose routed outdoors?

• AAccumulation of an explosive gas-air mixture inside the room which can ignite from electr…
• BFreezing of the gas meter index mechanism due to expansion cooling
• CDiscoloration of wall plasterwork caused by odorant additives
• DTripping of the main residual current device (RCD) on the consumer unit

What safety feature is incorporated into modern semi-submerged or surface-mounted domestic gas meter boxes to protect the meter governor?

• AA pressure relief vent or slam-shut safety valve mechanism that prevents over-pressurisat…
• BAn automatic water sprinkler head connected to mains cold water
• CA high-voltage anti-theft security mesh
• DA thermal insulation layer designed to maintain internal temperature at 40°C

When inspecting a newly installed gas meter, what visual check must be performed on the meter bracket and supports under BS 6400-1?

• AEnsure the meter is securely supported by an approved bracket so that no mechanical strai…
• BVerify that the meter hangs freely suspended from the flexible inlet hose
• CConfirm that the meter bracket is soldered directly to the electrical earth rod
• DCheck that the bracket allows the meter to tilt 45 degrees for easy dial reading

Under GIUSP, what classification is given to an installation where an open-ended gas pipe downstream of a meter control valve is un-capped?

• AImmediately Dangerous (ID)
• BAt Risk (AR)
• CNot to Current Standards (NCS)
• DSatisfactory

What is the lower explosive limit (LEL) and upper explosive limit (UEL) of natural gas (methane) in air by volume?

• A5% LEL to 15% UEL
• B1% LEL to 6% UEL
• C10% LEL to 30% UEL
• D2% LEL to 10% UEL

When installing a secondary gas meter inside a multi-occupancy building, what additional valve requirement applies under BS 6400-1?

• AA dedicated secondary Emergency Control Valve / Isolation Valve must be fitted immediatel…
• BNo isolation valve is required as the main building ECV controls all sub-meters
• CA non-return check valve must be fitted to prevent reverse gas metering
• DA automatic solenoid shut-off wired to the fire alarm panel is mandatory for all domestic…

An engineer carries out a tightness test on a new pipework extension (no appliances connected) upstream of a newly fitted U6 meter. After 2 minutes at 20 mbar, the manometer shows a drop of 0.5 mbar. What is the correct pass/fail judgment under IGEM/UP/1B?

• AFail — new pipework installations must show zero pressure drop
• BPass — any drop under 1 mbar is acceptable on new installations
• CPass — provided there is no smell of gas detected in the room
• DRe-test at 50 mbar before deciding

What device is fitted on a domestic ultrasonic smart gas meter (E6) to shut off the gas supply automatically in the event of severe gas leaks, tampering, or low credit?

• AAn internal motor-driven shut-off valve controlled by the meter electronics
• BA mechanical fusible plug that melts at 50°C
• CA weighted check valve operated by gas velocity
• DAn external manual lever operated by a solenoid cable

What distance must be maintained between a gas meter installation and uninsulated central heating hot water pipes or steam pipes under BS 6400-1?

• AAt least 25 mm (or insulated to prevent heat transfer exceeding 30°C ambient)
• BAt least 500 mm
• CAt least 1000 mm
• DNo clearance required if pipes are copper

Which Gas Safe Register publication provides the technical guidelines for classifying unsafe domestic gas situations in the UK?

• AIGEM/G/11 (Gas Industry Unsafe Situations Procedure)
• BBS 7671 On-Site Guide
• CHSE L56 Approved Code of Practice
• DCIBSE Guide B2

What is the relative density (specific gravity) of natural gas compared to air, and how does this influence meter compartment ventilation design?

• AApproximately 0.6 (lighter than air), meaning escaped gas rises and requires high-level v…
• BApproximately 1.5 (heavier than air), meaning gas sinks and requires low-level floor drai…
• CEqual to air (1.0), meaning gas distributes uniformly without buoyancy
• DApproximately 2.0 (heavier than air), requiring mechanical extraction fans

During meter exchange, an operative finds that the main equipotential bonding conductor is attached to the inlet service pipe BEFORE the Emergency Control Valve. What action is required?

• ARelocate the bonding connection to the consumer's outlet pipework within 600 mm of the me…
• BLeave the bonding connection as found as long as the wire is 10 mm²
• CRemove the bonding cable entirely as inlet pipes do not require electrical grounding
• DAttach a second bonding clamp to the ECV handle

What instrument is used to verify that no let-by is occurring across an Emergency Control Valve and to conduct tightness testing?

• AA fluid-filled U-tube manometer or calibrated electronic digital manometer
• BAn infrared thermal imaging camera
• CAn ultrasonic thickness gauge
• DA clamp-on multiconductor ammeter

If a gas rate test on a U6 meter shows an actual gas rate of 3.2 m³/h for an installation where connected appliances total 25 kW, what condition is indicated?

• AOver-firing / excessive gas rate (3.2 m³/h × 10.76 kWh/m³ ≈ 34.4 kW input), indicating in…
• BUnder-firing of appliances
• CNormal gas consumption matching total rated input
• DGovernor outlet pressure failure dropping below 10 mbar

What is the minimum height above ground level for the installation of an external surface-mounted domestic gas meter box under BS 6400-1?

• APositioned so the bottom of the box is between 450 mm and 1000 mm above finished ground l…
• BAt least 2000 mm above ground level
• CDirectly touching ground level with no clearance
• DExactly 300 mm below ground level

Under GSIUR Regulation 26(2), what must a gas operative do if they suspect gas is escaping from a primary meter installation?

• AImmediately isolate the ECV, inform the consumer, test for leakage, and if necessary noti…
• BWait 24 hours to monitor if the odor dissipates naturally
• CLight a match near meter unions to pinpoint the exact leak location
• DWrap self-amalgamating tape around the governor vent without isolating gas