Guidance Note 8 Overview
Guidance Note (GN8) outlines the entry routes to ACS assessment and the requirements for extending scope or range of work. GN8 (Table 2) is not intended to prevent or restrict progression, but to ensure consistency and provide practical guidance to support compliance with GSIUR Regulation 3 (Qualifications and Supervision). This helps ensure that gas engineers do not undertake work on appliances or systems for which they do not have sufficient training and experience.
Where an extension of scope or range training is required for experienced engineers, the training content shall be taken from the relevant IGEM/IG/1 training specification. Upon satisfactory completion, the engineer shall be issued with the appropriate certification.
- Guidance Note 8 v7.1 (184 kb)
What Does Guidance Note 8 Cover?
Guidance Note 8 (GN8) provides guidance on entry routes, scope, range, training, and experience for gas engineers. The key areas covered are outlined below:
Types of Gas Engineer
- New Entrant: A person wishing to achieve a recognised industry qualification to undertake gas work and gain Gas Safe Registration in that work category. This includes persons holding qualifications recognised as Category 2 (GN8 Appendix 1).
- Experienced Engineer: An engineer who is registered or has previously been registered on the Gas Safe Register (GSR). The engineer must possess, or have previously held, an ACS core (or relevant qualification) for a minimum of 12 months.
Range & Scope
- Extending Scope: Moving from one sector to another, e.g., Domestic to Commercial (see Table 4).
- Extending Range: Remaining within the same sector but adding additional appliances, e.g., holding CCN1 & CENWAT and adding HTR1 (see Table 3).
Training & Experience
- MLP (Managed Learning Programme): An MLP approved by the Authoriser of Training (IGEM) in accordance with the requirements of IGEM/IG/1.
- MLP – Bridge: Recognisers of Training must use derivatives of their approved MLPs for engineers extending Scope or Range within twelve months of completing their qualification or core ACS.
- MLP – RPL: Recognisers of Training must use derivatives of their approved MLPs to develop changeover MLPs, taking into account any Recognition of Prior Learning (RPL).
- RPL – Bridge: This route is designed to build on an existing MLP or qualification.
Evidence
- RWE (Realistic Work Environment): Appliances and equipment installed with realistic workplace conditions to provide practical experience.
UK Schemes with Access to ACS Assessments
Guidance Note 8 is supported by the following appendices:
Suitable Schemes – GN8 Appendix 1
- Guidance Note 8 Appendix 1 v9.5 (818 kb)
This appendix provides a list of UK Qualifications and Certification Schemes that are eligible for accessing ACS Assessments e.g. DNGA3 Managed Learning Programme. These qualifications are classified as either Category 1 or Category 2.
- Category 1: The ACS assessments for first time Category 1 applications SHALL be relevant to the presented qualification unless additional evidence is presented to show that their work experience is relevant.
- Category 2: Hold qualifications detailed in Guidance Note 8 and provide written evidence to the AC confirming that they have undertaken work experience and approved training for the range of assessments to be undertaken.
Unsuitable Schemes – GN8 Appendix 2
- Guidance Note 8 Appendix 2 v3 (97 kb)
This appendix lists UK Qualifications and Certification Schemes that are not suitable for accessing ACS Assessments.
ACS Core Assessment Categories
ACS Core assessments are classified into three groups: Category A, Category B, and Category C. Clear pathways are defined for progressing from Categories B and C to Category A.
Table 1
Gas Engineer Routes & Requirements
This section is all classed as Table 2
Experienced Gas Engineer
| Route | Entrant Description | Aim | Training | Experience | RWE Evidence | IGEM* |
|---|---|---|---|---|---|---|
| 1 | Holding an existing or expired ACS or GCS certificate or gas qualification10 with equivalent ACS certificate | Renew certificate | Optional | N/A | N/A | Outside scope |
| 2 | Holding a recognised gas qualification as listed and indicated as Category 1 on GN8 Appendix 1 | Extend range of work within the same sector | Required (See Table 3) | 2 Gas Safe Registered and a minimum of twelve months from completion of qualification or core ACS | 1 Required if no documented evidence of onsite experience in extension applied for | Outside scope |
| 3 | Holding Category A B or C Core ACS Certificate | Extend range of work within the same sector | Required (See Table 3) | 2 Gas Safe Registered and a minimum of twelve months from completion of qualification or core ACS | 1 Required if no documented evidence of onsite experience in extension applied for | Outside scope |
| 4 | Holding Category A ACS Certificate | Extend scope of work to a different sector Changeover Examples: CCN1 to CoDNCO1 or CoDC1 COCN1 to CoCDN1 | Required (See Table 4) | 2 Gas Safe Registered and a minimum of twelve months from completion of qualification or core ACS | 1 Required if no documented evidence of onsite experience in extension applied for | Outside scope |
| 5 | Deliberately left blank (now included in Route 3) | |||||
| 6 | Experienced foreign national gas engineer holding a valid certificate of gas competence or license to practice gas work in the country of issue | Remain in same sector e.g. Domestic | Optional | 3 Experience declaration signed by engineer | N/A | Outside scope |
New Entrant WITH Transferable Skills or Experience
| Route | Entrant Description | Aim | Training | Experience | RWE Evidence | IGEM* |
|---|---|---|---|---|---|---|
| 7 | Holding a recognised qualification as listed and indicated as Category 2 on GN8 Appendix 1 or holding Category C Core ACS Certificate | Extend scope of work to a different sector | 4 MLP – RPL | 4 MLP – RPL | 6 If required to support onsite experience | Within scope |
| 8 | Experienced in gas work (gained legally within the scope of GS(I&U)R) | Gain ACS in that sector e.g. Industrial experience applying for COCN1 or LPG (leisure site) experience applying for CCLP1 LAV etc | MLP | 5 MLP – RPL | 6 If required to support onsite experience | Within scope |
| 9 | Experienced in gas work (gained legally from outside scope of GS(I&U)R) | Gain ACS in that specific category e.g. Engineer working on gas engines in factory wishing to gain CGFE1 | Required | 8 Experience declaration signed by engineer and employer | 1 If required to support onsite experience | Outside scope |
| 10 | Holding Category B ACS Certificate | Extend scope of work to a different sector, e.g. CMA1 to CCN1 | 9 RPL – Bridge | 9 RPL – Bridge | 1 If required to support onsite experience | Outside scope |
| 11 | Holding a qualification as listed and indicated as unsuitable on GN8 Appendix 2 | Gain ACS | 4 MLP – RPL | MLP | 6 If required to support onsite experience | Within scope |
New Entrant WITHOUT Transferable Skills or Experience
| Route | Entrant Description | Aim | Training | Experience | RWE Evidence | IGEM* |
|---|---|---|---|---|---|---|
| 12 | Working to achieve a Category A or B Core | Gain ACS | MLP | MLP | 6 If required to support onsite experience | Within scope |
| 13 | Working to achieve a Category C Core or ICPN1LS or ICAE1LS or EFJLP1 | Gain ACS | 7 Required | 7 Required | 7 If required to support onsite experience | Outside scope |
*Routes 7, 8, 11 & 12: are within the Recogniser of Training Scope of IGEM
*Routes 1 – 6, 9, 10 & 13: are outside the Recogniser of Training Scope of IGEM
Table 2 Notes
Note 1: Where opportunities are limited, or not available, for experienced GSR engineers to gain onsite experience to extend their Scope or Range of work, Realistic Work Environment (RWE) evidence must be used as an alternative. The RWE evidence must be recorded in the candidate’s file and clearly identified as RWE. Appliances and equipment used for RWE training should be installed within an approved training centre, replicating typical workplace installations (or parts thereof).
Note 2: Before extending Scope or Range of work, gas engineers must provide evidence to the centre that they are Gas Safe Registered and that a minimum of twelve months has passed since completion of their qualification or core ACS.
Exceptions to Note 2:
- Where an engineer extends Scope or Range less than twelve months after completing their qualification or core ACS, they must provide Gas Safe Registration and undertake an MLP-Bridge via a recognised training provider in accordance with the relevant IGEM/IG/1 training specification.
- Upon satisfactory completion of the MLP-Bridge, the engineer will be issued with a “Certificate of Training” or a “Validation of Training Report” by, or on behalf of, the Recogniser of Training.
- Engineers holding CCN1 must provide Gas Safe Registration but are not required to wait twelve months since completion of their qualification or core ACS before undertaking training and assessment for domestic metering competencies.
Note 3: A Declaration signed by a Foreign National engineer must include details of the Scope of work previously undertaken and be supported by translated evidence of their license to work in their home country.
Note 4: MLP – RPL: This route is designed to build on an existing MLP or qualification. A documented technical interview must determine any training and experience gaps before undertaking the agreed MLP or Qualification RPL route. Centre training duration will be similar, if not the same, as required for New Entrant MLP, though reductions can be applied if cross-referenced to existing qualifications. This reduction also applies to onsite experience durations and evidence, which must be from the previous three years. Centres must agree any MLP reductions with their Certification or Awarding Body in advance.
Note 5: Witnessed Testimony (GSR Engineer): A signed declaration by the GSR engineer with whom the experience was gained must detail the exact work undertaken and be supported by evidence. This evidence may support the MLP but cannot fully replace evidence required by the MLP provider. Evidence must be from the previous three years and cannot exceed 50% of the portfolio content.
Note 6: RWE evidence may be used to support onsite experience gaps, e.g., where the full range of appliances or flue systems is unavailable. RWE evidence must be obtained at an approved MLP training centre, cannot exceed 10% of the portfolio content, and must be recorded in the candidate’s portfolio as RWE.
Note 7: Training must be relevant to the limited-scope ACS Assessment being applied for. Onsite experience must be supported by a Witnessed Testimony from the GSR engineer with whom the experience was gained, detailing the exact work undertaken.
Note 8: Evidence must include a Witnessed Testimony statement signed by the engineer and each employer (if more than one), declaring that all evidence and supporting documentation is correct, accurate, and a true account of the gas work undertaken. The statement must include the name, address, and contact details of each employer, along with details of the gas work undertaken at each location. Supporting evidence for each address must also be included.
Note 9: RPL – Bridge: This route is designed to build on an existing MLP or qualification. A documented technical interview must determine any training and experience gaps before undertaking the agreed RPL Bridge route. Refer to Table 4 for training duration.
Note 10: Where an engineer has not been previously Gas Safe Registered and their qualification predates the ACS-aligned qualifications, a technical interview will be required to determine if additional training is necessary.
Guided Learning Hours for GSR Operatives
(Previously known as GN8 Appendix 3)
The durations indicated in Table 3 and Table 4 are provided as guidance for existing GSR operatives when extending either their Scope or Range of work.
Examples of activities that can contribute to Guided Learning include:
- Classroom-based learning supervised by a Teacher
- Work-based learning supervised by a Teacher or a Gas Safe Registered mentor with experience and competencies relevant to the task
- Live webinar or telephone tutorial with a Teacher in real time
- E-learning supervised by a Teacher in real time
- Any form of assessment conducted under the Immediate Guidance or Supervision of a Teacher, supervisor, tutor, or other appropriate education or training provider
Extending Range of Certification
Table 3
| # | Certification Range | Hours | Days |
|---|---|---|---|
| 1 | Installation and Servicing of Domestic Central Heating and Hot Water Appliances (including System Design and Controls) (CENWAT) | 31 | 4.5 |
| 2 | Heating Design, Heat Loss and Comfort Conditions | ||
| 3 | Hot Water Safety | ||
| 4 | Water Regulations | ||
| 5 | Installation and Servicing of Domestic Ducted Air Heaters (DAH1) | 7 | 1 |
| 6 | Installation and Servicing of Domestic Cooking Appliances (CKR1) | 7 | 1 |
| 7 | Installation and Servicing of Domestic Space Heating Appliances (HTR1) | 7 | 1 |
| 8 | Installation of Domestic Meters (MET1) | 7 | 1 |
| 9 | Non-Domestic and Catering Appliances (per appliance) | 7 | 1 |
Extending Scope of Certification
Table 4
| # | Certification Scope | Hours | Days |
|---|---|---|---|
| 1 | Natural Gas to LPG Installations (CoNGLP1 PD, LAV, RPH, B) | 13 | 2 |
| 2 | LPG Appliances (Per Appliance, e.g. HTRLP2 etc.) | 4 | 0.5 |
| 3 | Installation and Servicing of Non Domestic Heating Appliances (CoDNCO1, CIGA1, CDGA1 & CORT1) | 40 | 6 |
| 4 | Installation and Servicing of Non-Domestic Catering Appliances (CoDC1 & COMCAT 1 & COMCAT 3) | 32 | 5 |
| 5 | Installation and Servicing of Non-Domestic Laundry Appliances (CoCCLNG1 & CLE1) | 33 | 5 |
| 6 | Installation of Non Domestic Pipework (CoDNCO1, ICPN1, TPCP1/TPCP1A) | 33 | 5 |
| 7 | Commercial to Domestic Natural Gas (CoCDN1) | 45 | 7 |
| 8 | LPG to Domestic Natural Gas (CoLPNG1) | 13 | 2 |
| 9 | LPG External Pipework, (VESLP1, 2 and TPCP1) | 21 | 3 |
Table 3 & 4 Notes
Note 1: The durations are indicative and should not be considered as minimum, maximum, or fixed.
Note 2: The learning inputs are primarily based on guided learning within a classroom environment with a Teacher present. Other complementary learning methods—such as e-learning, project work, or experience gained by working with a Gas Safe Registered mentor—may also be acceptable, subject to approval by the External Verifier.
ACS Gas Training Courses
ACS & Guidance Note 8 FAQs
Guidance Note 8 applies to anyone wishing to access an ACS gas assessment, including new entrant gas engineers and experienced engineers who want to renew, extend, or change their scope or range of work. It is used by training providers, assessment centres, and Gas Safe registered engineers to ensure the correct route, qualifications, and experience are in place before assessment.
GN8 helps confirm that engineers meet the requirements of Gas Safety (Installation and Use) Regulations and only work within areas they are competent and certified for.
Extending range means adding more appliance categories within the same sector, such as holding CCN1 and CENWAT and then adding HTR1 or CKR1 for additional domestic appliances.
Extending scope means moving into a different sector of gas work, for example from domestic gas (CCN1) to commercial, commercial catering, LPG, or non-domestic gas qualifications such as CoDNCO1 or CoDC1.
Guidance Note 8 sets out the specific training hours, experience, and assessment routes required for each type of extension.
In Guidance Note 8, training is described as either required or optional depending on an engineer’s existing qualifications, experience, and the type of extension they are applying for.
Required training applies when an engineer is:
- Extending their scope of work (for example, moving from domestic to commercial gas work), or
- Adding a new range of appliances where they do not already have proven, relevant experience.
In these cases, GN8 refers engineers to Table 3 (Extending Range) and Table 4 (Extending Scope), which provide guidance on the typical learning hours and training content needed to ensure competence before undertaking ACS assessment.
Optional training applies when an engineer already holds:
- A recognised gas qualification or valid ACS certification, and
- Sufficient documented on-site experience in the category they are renewing or extending.
If the assessment centre and training provider are satisfied that the engineer’s existing knowledge and experience meet the requirements, additional formal training may not be necessary. However, engineers must still meet eligibility rules such as Gas Safe registration and minimum experience timeframes.
Yes. Guidance Note 8 is used by ACS assessment centres and training providers to determine whether a candidate is eligible to undertake an ACS assessment. It ensures consistent national standards for entry routes, training, and competence across the gas industry.
While GN8 itself is guidance, it supports legal compliance with Gas Safety (Installation and Use) Regulations and is followed by awarding bodies, certification bodies, and Gas Safe Register requirements.
A Managed Learning Programme (MLP) is an approved training route for new entrant gas engineers or engineers extending their scope or range of work. MLPs are designed in line with IGEM/IG/1 training specifications and include both classroom learning and practical experience in a Realistic Work Environment (RWE).
GN8 also recognises variations such as:
- MLP – RPL (Recognition of Prior Learning) for engineers with relevant experience or qualifications
- MLP – Bridge for engineers extending scope or range within 12 months of qualification
Successful completion results in certification that allows access to ACS assessments.
Realistic Work Environment (RWE) evidence is practical training carried out in approved training centres where appliances and systems are installed to replicate real workplace conditions. It is used when engineers cannot gain sufficient on-site experience in certain appliance categories or systems.
GN8 limits RWE evidence to a percentage of a candidate’s portfolio and requires it to be clearly recorded and verified by the training provider.
Guidance Note 8 includes appendices listing suitable and unsuitable UK qualifications for accessing ACS assessments.
- Appendix 1 lists acceptable qualifications and schemes, classed as Category 1 or Category 2.
- Appendix 2 lists qualifications that are not suitable routes into ACS assessments.
These lists help ensure that only candidates with appropriate training and experience progress to ACS certification.
Guidance Note 8 protects both engineers and the public by ensuring gas work is only carried out by individuals who are properly trained, assessed, and competent. It provides clear progression routes for careers in domestic, commercial, and industrial gas work while maintaining consistent national safety standards.
It also helps engineers avoid undertaking work outside their certified scope, which could lead to legal, safety, and insurance issues.
‘Recogniser of Training Scope of IGEM’ refers to whether a training route or qualification is formally approved and overseen by the Institution of Gas Engineers and Managers (IGEM) through its role as the Authoriser and Recogniser of Training for gas industry Managed Learning Programmes (MLPs).
When a route is described as being within the Recogniser of Training Scope of IGEM, it means the training programme:
- Has been reviewed and approved by IGEM
- Meets the requirements of IGEM/IG/1 training specifications
- Can be delivered by an IGEM-recognised training provider
- Is suitable for new entrants or engineers following approved MLP routes into ACS assessment
Routes listed as outside the Recogniser of Training Scope of IGEM are not delivered under IGEM-approved Managed Learning Programmes. These routes typically apply to:
- Experienced Gas Safe registered engineers
- Engineers renewing or extending existing ACS qualifications
- Foreign national engineers using prior competence evidence
- Engineers using Recognition of Prior Learning (RPL) or Bridge routes
In these cases, eligibility is still determined by Guidance Note 8, but the training does not fall under IGEM’s formal Recogniser of Training framework.
Further Information
Still unsure about which path is right for you? Or, perhaps you’re a qualified gas engineer interested in diversifying your skills or honing a specialism? Then please don’t hesitate to contact our Training team.
