ACS GAS Courses - Domestic Natural Gas Safety (CCN1)

CCN1, Domestic Gas Safety, is the core or initial qualification for engineers working on gas appliances and must be successfully completed before further specific gas appliance qualifications can be attempted, for example boilers, cookers, or heaters.

Who is this for?

  • For new entrants into the gas industry who have completed a recognised plumbing qualification or have completed the NICEIC Elementary Gas Course (Initial Assessment)
  • For existing plumbing and heating engineers renewing gas qualifications (Reassessment). CCN1 re-assessment can take place up to 6 months early without losing time

Entry Requirements

ACS Reassessment for renewal of gas qualifications

  • Candidates must produce original or previous certificates as demonstrable evidence prior to reassessment.
  • We would always suggest that training is undertaken prior to assessment, although not mandatory we do advise that training is often essential due to statutory or industry changes.


ACS Initial assessment for new entrants joining the gas industry who have completed a recognised qualification and can meet the requirements of the guidance notes.

For further guidance on entry requirements: see Suitable Qualifications  and Non Suitable Qualifications.

  • EU Skills approved City & Guilds craft certificate or NVQ level 2 or equivalent, and
  • a written summary of your 'on the job' work experience, and
  • an evidence portfolio with a minimum of 6 different gas appliance installations 

Course Duration

Theory and practical assessment.

  • For reassessment, allow up to 5 days.
  • For initial assessment and dependent on learner’s prior knowledge and on site gas work experience allow up to 5 to 7 days.


Course Outcome

  • Successful completion of CCN1 will enable the holder of a certificate of competence to apply to the Gas Safe Register so that gas work can be undertaken legally within the scope of the Gas Safety in use Regulations. (GS(IU)R) Please note in addition, the operative must also hold the relevant appliance element relating to the work they wish to undertake.

    Successful completion of the core assessment (CCN1) provides a route to the following training modules:                       

    • CKR1 Cookers                     
    • HTR1 Heaters
    • CENWAT Central heating and water heaters
    • MET1 Meters
    • LAU1 Laundry
    • DAH1 Warm Air Units
    • LEI1 Natural Gas leisure and miscellaneous appliances.



  • Reassessment must take place within the 12 months following the certificate expiry date. Candidates may also undertake re-assessment of any element up to 6 months early without losing any time
  • Operatives undertaking gas assessment for the first time must complete a recognised training programme.
  • Candidates undertaking initial assessments for the first time should allow at least half a day per module for assessment.
  • Candidates must produce any previous certificates as proof of evidence prior to reassessment.
  • All candidates who wish to undertake gas training and or assessment must produce evidence of their qualifications and meet required category 1 or 2 or the following criteria:
    • Category 1 candidate is a fully experienced gas operative and has a gas fitting qualification or certificates of gas safety competence.
    • Category 2 candidate is already involved in a trade associated with gas work, e.g. plumbing, or holds a nationally recognised qualification e.g. NVQ2, City & Guilds craft certificate for the associated trade association.