CODC1, Changeover Domestic to Commercial Gas safety, adds to CCN1 and provides for the core qualification that is normally a pre-requisite required before attaining other additional commercial catering appliance certificates. There are some exceptions to this, but generally most candidates must complete CODC1, to enhance their CCN1 qualification before adding commercial catering appliances.
CODC1 training takes half a day to complete, with a small amount of extra time potentially being required to undertake and successfully pass the associated COCN1 theory and practical assessments.