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2026 Statistics

Key Facts: RGII Domestic Gas Safety Exam

100

Practice Questions

OpenExamPrep

5 years

Re-certification Cycle

RGII

I.S. 813

NSAI Gas Standard

NSAI

1800 20 50 50

GNI Gas Emergency

Gas Networks Ireland

75-80%

Theory Pass Mark

METAC/QQI

Level 6

Prerequisite Craft Level

RGII

The RGII Domestic Gas Safety theory assessment is the mandatory qualification required to become and remain a Registered Gas Installer (RGI) in the Republic of Ireland. It covers Irish Standard I.S. 813 (Domestic Gas Installations), testing competence across 5 domains: legislation and standards, combustion and flues, pipework and tightness testing, appliance commissioning, and electrical safety. Installers must renew this certification every 5 years via the DGA reassessment. Our free prep includes 100 high-quality practice questions with explanations and an AI tutor.

Sample RGII Domestic Gas Safety Practice Questions

Try these sample questions to test your RGII Domestic Gas Safety exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under the Energy (Miscellaneous Provisions) Act 2006, which body is designated as the Gas Safety Supervisory Body (GSSB) responsible for registering gas installers in Ireland?

A.Health and Safety Authority (HSA)

B.Register of Gas Installers of Ireland (RGII)

C.Commission for Regulation of Utilities (CRU)

D.National Standards Authority of Ireland (NSAI)

Explanation: Under Section 13 of the Energy (Miscellaneous Provisions) Act 2006, the Commission for Regulation of Utilities (CRU) appoints a designated body to be the Gas Safety Supervisory Body (GSSB) - historically the Register of Gas Installers of Ireland (RGII). Its role is to maintain the register of installers, perform safety audits, and promote safety. While the CRU designates this role, RGII is the actual registry body.

2What is the statutory requirement regarding gas works in domestic dwellings in the Republic of Ireland?

A.Only complex commercial boiler installations require registration.

B.It is a legal offence for anyone other than a Registered Gas Installer (RGI) to carry out domestic gas works.

C.Gas works can be performed by any competent plumber, provided they are supervised by a homeowner.

D.Only natural gas installations are regulated; LPG installations are exempt.

Explanation: Under Irish law (Energy (Miscellaneous Provisions) Act 2006), it is a criminal offence for any person other than a Registered Gas Installer (RGI) to carry out 'Designated Gas Works' in a domestic setting. This applies to both Natural Gas and Liquefied Petroleum Gas (LPG) installations. Competence alone is insufficient without registration.

3Which Irish standard governs the installation of domestic gas systems using Natural Gas or Liquefied Petroleum Gas (LPG)?

A.I.S. 813

B.I.S. 820

C.I.S. EN 1949

D.I.S. 3216

Explanation: I.S. 813 is the national standard for 'Domestic Gas Installations' in Ireland, published by the National Standards Authority of Ireland (NSAI). It covers all aspects of piping, ventilation, flues, and appliance installation for both Natural Gas and LPG. I.S. 820 is for non-domestic gas installations.

4When must an RGI issue a Declaration of Conformance Cert 1 to a domestic customer?

A.After performing a routine annual safety service on an existing boiler.

B.Following a new gas installation or installation extension that requires a new connection to the gas network.

C.Only when replacing a gas meter on behalf of Gas Networks Ireland.

D.When issuing a warning notice for an unsafe appliance.

Explanation: Declaration of Conformance Cert 1 is the certificate issued for new gas installations or extensions to existing installations that require a new connection to the gas network (meter fit). Cert 2 is used for boiler replacements, and Cert 3 is used for service, repair, or safety inspections. A warning notice is a separate document.

5What is the function of a Declaration of Conformance Cert 2 in the Irish gas safety scheme?

A.It certifies a new gas installation requiring a new meter connection.

B.It is used specifically for the replacement of an existing domestic gas boiler.

C.It certifies the safety of a non-domestic LPG storage tank.

D.It is a safety certificate issued by a landlord to a tenant on change of occupancy.

Explanation: Declaration of Conformance Cert 2 is specifically designed and used for boiler replacements on existing gas installations (where a gas meter is already in place). This certificate ensures that the replacement boiler complies with I.S. 813 requirements. New installations require Cert 1.

6Which Declaration of Conformance certificate should an RGI issue after completing a safety inspection or repair work on a domestic gas cooker?

A.Cert 1

B.Cert 2

C.Cert 3

D.Cert 4

Explanation: Cert 3 is the Declaration of Conformance used for existing gas installations where work such as servicing, safety testing, appliance commissioning (except boiler replacements), or repairs have been carried out. It verifies that the specific work completed complies with standards. Cert 4 does not exist in the RGII domestic system.

7Under the Safety, Health and Welfare at Work Act 2005, what is the duty of a self-employed gas installer regarding gas safety?

A.They are only responsible for their own safety on site.

B.They must ensure, as far as reasonably practicable, that their work activities do not expose others to safety or health risks.

C.They must notify the HSA before starting any domestic gas installation.

D.They are exempt from the requirement to produce a Safety Statement.

Explanation: Under Section 12 of the 2005 Act, every self-employed person has a duty to ensure, as far as is reasonably practicable, that individuals not in their employment (such as clients, visitors, or members of the public) are not exposed to risks to their safety or health. This applies to all gas work. Notification is not required for standard jobs.

8An RGI discovers an appliance that presents an immediate danger to life or property (Class A hazard). What action must they take under RGII guidelines?

A.Advise the client to get it repaired within 14 days and issue a Cert 3.

B.With the client's permission, immediately isolate the appliance from the gas supply, attach a 'Safety Alert' warning label, and issue a Warning Notice.

C.Notify the local authority building inspector within 24 hours.

D.Replace the appliance immediately, even without the homeowner's consent.

Explanation: For Class A hazards (Immediate Danger), the RGI must, with the owner's consent, isolate the gas supply to the dangerous appliance, label it clearly with a 'Danger - Do Not Use' safety alert label, and issue a formal Warning Notice (Unsafe Gas Installation). If consent is refused, the installer must contact Gas Networks Ireland/LPG supplier to cut off the supply.

9What defines a Class B hazard on a domestic gas installation under Irish safety standards?

A.An installation that is safe but does not comply with the latest edition of I.S. 813.

B.An installation that is unsafe and presents a potential future danger, requiring correction as soon as possible.

C.An appliance with a minor cosmetic defect that does not affect safety.

D.A gas leak that can be easily repaired with tape.

Explanation: A Class B hazard (At Risk) indicates that the installation contains a defect that represents a potential danger to life or property, but is not immediately dangerous. The user must be formally warned, the defect explained, a warning label attached, and correction advised as soon as possible. Safe but non-compliant installations are categorized as 'Not to Current Standards'.

10Under I.S. 813, what is the status of an existing domestic gas installation that is safe but does not meet the latest installation regulations?

A.It must be classified as a Class A hazard and disconnected.

B.It should be classified as a Class B hazard and labelled.

C.It is classified as 'Not to Current Standards' (NCS) and the installer should advise the customer on recommended improvements.

D.It must be immediately reported to the CRU for enforcement action.

Explanation: Installations that are safe to operate but do not comply with the current edition of I.S. 813 (due to changes in standards over time) are classified as 'Not to Current Standards' (NCS). The installer should note this on the Declaration of Conformance or service report and advise the customer of potential safety upgrades, but isolation is not required.

About the RGII Domestic Gas Safety Exam

The RGII Domestic Gas Safety (DGS) / Domestic Gas Assessment (DGA) is the mandatory safety qualification for Registered Gas Installers (RGI) in Ireland. Based on Irish Standard I.S. 813, it tests core gas safety competencies including legislation and standards, combustion chemistry, ventilation, flue systems, pipework installation, let-by and tightness testing, purging, appliance safety controls, and safe electrical isolation. RGI installers must pass this assessment every 5 years to maintain their registration and legally carry out gas works.

Assessment

Multiple modular written/theory exams covering safety standards and regulations, plus a comprehensive practical assessment demonstrating installation, testing, and commissioning skills. This practice bank is 100 selected-response items.

Time Limit

Varies by module (typically 1 to 2 hours per theory paper)

Passing Score

Typically 75-80% for the theory papers, and 100% competence in safety-critical practicals

Exam Fee

Varies by training center; typically ~€600-€900 for full course, ~€350-€500 for DGA reassessment (RGII (Register of Gas Installers of Ireland) / Commission for Regulation of Utilities (CRU))

RGII Domestic Gas Safety Exam Content Outline

20%

Legislation & Standards

The Energy Act 2006, GSSB/RGII rules, NSAI standards including I.S. 813, HSA duties, and Declarations of Conformance (Cert 1, 2, and 3)

20%

Combustion & Flues

Combustion principles (complete/incomplete), CO hazard limits, room-sealed and open flues, draught diverters, and ventilation requirements

20%

Pipework & Testing

Copper and steel pipe jointing, sleeving, let-by and tightness testing procedures under I.S. 813, meter losses, and gas purging

20%

Appliances & Controls

Boiler installation, freestanding cookers and stability chains, Flame Supervision Devices (thermocouples), air switches, and commissioning logs

20%

Electrical & Safety Procedures

Safe electrical isolation, dead testing, earth continuity and equipotential bonding, CO emergency actions, and gas leak protocols

How to Pass the RGII Domestic Gas Safety Exam

What You Need to Know

Passing score: Typically 75-80% for the theory papers, and 100% competence in safety-critical practicals
Assessment: Multiple modular written/theory exams covering safety standards and regulations, plus a comprehensive practical assessment demonstrating installation, testing, and commissioning skills. This practice bank is 100 selected-response items.
Time limit: Varies by module (typically 1 to 2 hours per theory paper)
Exam fee: Varies by training center; typically ~€600-€900 for full course, ~€350-€500 for DGA reassessment

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

RGII Domestic Gas Safety Study Tips from Top Performers

1Review the core clauses of Irish Standard I.S. 813, especially regulations regarding ventilation free area and flue terminal clearances

2Memorize the step-by-step procedure for let-by testing (7-10 mbar for 1 min) and tightness testing (20/37 mbar for 2 min after 1 min stabilization)

3Learn the action thresholds for carbon monoxide: 35 ppm is the immediate Class A danger limit requiring appliance isolation and evacuation

4Understand the electrical safety requirements: perform safe isolation and verify the circuit is dead before touching components, and check earth continuity

5Know the safety controls: thermocouples generate 10-30 mV to hold open valves, and air switches verify fan operation before gas valves open

6Practice all 100 questions in this bank and make sure you understand the reasoning behind each explanation

Frequently Asked Questions

What is the passing score for the RGII Domestic Gas Safety exam?

Theory papers typically require a passing mark of 75-80% depending on the training provider and certification body. The practical assessments require 100% competence in safety-critical areas; any safety violation results in an automatic fail.

How often must RGI installers renew their gas safety certification in Ireland?

Gas safety certification (DGS/DGA) follows a 5-year cycle. Registered Gas Installers (RGI) must complete periodic retraining and sit a Domestic Gas Assessment (DGA) reassessment every 5 years to maintain their RGI registration.

What standard governs domestic gas installations in the Republic of Ireland?

The primary national standard is I.S. 813 (Domestic Gas Installations), published by the National Standards Authority of Ireland (NSAI). It outlines the mandatory requirements for design, piping, ventilation, flues, and appliance installations.

What is the difference between Cert 1, Cert 2, and Cert 3 in Ireland?

Cert 1 is issued for new gas installations or extensions requiring a new meter connection. Cert 2 is used specifically for boiler replacements on existing systems. Cert 3 is used for service, repair, or safety inspections of existing systems.

Can any qualified plumber carry out gas works in Ireland?

No. Under the Energy (Miscellaneous Provisions) Act 2006, it is a criminal offence for anyone other than a Registered Gas Installer (RGI) to carry out designated gas works in a domestic setting. Plumbing qualifications alone are not sufficient.

Is this practice test bank free to use?

Yes, our practice bank of 100 questions is completely free. It covers all 5 core modules of the domestic gas safety syllabus with detailed explanations and an AI tutor to help you study.