Health and safety are essential when it comes to training and working in the gas industry, which is why there are several in-depth modules, assessments and registrations to complete before an engineer can get Gas Safe Registration and begin working in the field.
The Nationally Accredited Certification Scheme or ACS is the industry-recognised and accepted route for operatives to gain a certificate of competence that’s needed to become a member of the Gas Safe Register. Gas Safe Registration is a mandatory legal requirement for all gas engineers operating in the UK.

What is the ACS assessment?
The ACS assessment is the industry-recognised route for gas engineers to gain a certificate of competence.
The scheme, which is overseen by the United Kingdom Accreditation Service (UKAS), covers all areas of gas work, including domestic natural gas, LPG, commercial heating, commercial catering, commercial laundry, meter installation and emergency service provision.
When do gas engineers do their ACS assessment?
There are generally two instances when a gas engineer or trainee engineer will complete their ACS assessment.
The first is when an individual has come to the end of an industry-recognised training course in gas work, has completed their gas portfolio and is preparing to begin working in the industry for the first time.
There will also be times when an experienced engineer, who already holds a relevant qualification, needs to take an ACS reassessment to prove they are still able to competently carry out work to the latest industry regulations.
A quick guide to ACS assessment courses at Able Skills
The ACS assessment course talked about in this quick guide is for anyone who is looking to be assessed on an appliance of any kind for the very first time or where 12 months have elapsed since certificate expiry. The length of the course will depend on the appliances you are planning to gain certificates in.
What is the ACS course at Able Skills?
Here at Able Skills, we offer a comprehensive course allowing you to take whatever domestic aspects you choose.
Remember, if you haven't been tested on a specific aspect, for example, Central Heating Boilers, doing work on them is illegal, as you will need to complete an assessment on every appliance you work with!
In all areas of gas work, there is a core gas safety assessment which must be achieved before an individual appliance assessment can be undertaken.
List of appliances in Initial ACS assessment course:
- CCN 1/CPA1: Core Gas Safety
- CENWAT 1: Central Heating Boilers
- CPA 1: Combustion Performance Analysis
- CKR 1: Domestic Cookers
- HTR 1: Gas Fires and Wall Heaters
- MET 1: Meters
- DAH 1: Warm Air Heating Appliances
Undertaking your ACS is more about assessment than it is about learning. Most individuals doing their Initial ACS will be doing so for the first time, having completed a comprehensive programme of learning and work placement. Upon successful completion of the ACS Initial Assessment, you will receive a certificate in each of the areas you chose to cover.
What students say about Able Skills ACS
I did my gas course & ACS with Able Skills and, went back a month ago to do gas cooker and fire ticket. The teachers were very helpful and patient 10/10 service – Damian via Trustpilot
Just completed my ACS gas recertification. Really good facility and excellent trainer. Was also an extremely competitive price. Will definitely use again and also highly recommend! – Steve via Trustpilot
Just passed my ACS with Able skills.. what an amazing establishment, I started my gas course last year moved on to my portfolio with the help of Able skills and did all my work portfolio checks and finally had my exams this week and passed! – Fahad via Trustpilot

How do I become 'Gas Safe Registered'?
To become a gas engineer, you’ll need to apply for Gas Safe Registration. There are several crucial steps to ensure compliance and eligibility before registration.
Firstly, you’ll need to complete a suitable gas training programme and work placement, where you’ll gather a portfolio of evidence to prove your knowledge, skill and competence to undertake gas work safely. You’ll then need to gain ACS certificates in the areas of work in which you would like to be 'Gas Safe Registered'.
Next, it's time to apply for Gas Safe Registration. Visit Gas Safe for more information on the application process.
There is a probation period once you have become registered, during this time you must keep a record of all gas work carried out for Gas Safe Register to inspect. Certain tasks, like the installation of an appliance, must be notified to Gas Safe Register as detailed in the rules of registration.
What happens if I fail my ACS at Able Skills?
Please be aware that at Able Skills, we will allocate a full 5-days for this assessment process.
If you fail at any stage or run out of time, you will need to rebook and you will need to pay again for the full week's fees.
Our student/instructor ratio is set by our certificating body, and we are unable to slot in odd days.
We book these 5-days as we think that this is an adequate length of time to complete the ACS assessment.
FAQs about ACS assessment
How long does an ACS assessment take to complete?
An ACS assessment can usually be completed in around a week.
Is the ACS gas exam hard?
The ACS assessment is designed to prove competency, so by its nature is challenging but achievable as you’ll already have the relevant knowledge and skills from the training programme and portfolio.
How long is ACS valid for?
ACS accreditation lasts for five years, after this date an engineer must complete an assessment or reassessment regardless of experience.
How often do I need to do my ACS?
ACS certificates must be renewed within 12 months of expiry to qualify an engineer as a Category 1 candidate that is eligible for reassessment. If your certificate expiry is more than 12 months, the engineer must complete an initial assessment again.
Find out more about gas training and ACS at Able Skills
You can find more information about completing your ACS initial assessment with Able Skills. We also run a variety of other Gas courses and Plumbing courses. If you would like some more information about any of the gas or plumbing courses, then do not hesitate to call us on 01322 280 202 or visit the training centre. We are located in Dartford at the London & Kent border just as short walk away from the train station.