This document defines the construction, safety, qualification test and documentation requirements of modular or factory-matched hydrogen gas generation appliances or systems, herein referred to as hydrogen generators, using electrochemical reactions to electrolyse water to produce hydrogen. This document is applicable to hydrogen generators that use the following types of ion transport medium: aqueous alkaline (basic) electrolytes, such as solutions of potassium hydroxide or sodium hydroxide; aqueous acidic electrolytes such as dilute sulphuric acid; solid polymeric materials with acidic function group additions, such as acid proton exchange membrane (PEM); solid polymeric materials with basic function group additions, such as anion exchange membrane (AEM). This document is applicable to hydrogen generators intended for industrial, commercial and residential uses, in indoor or outdoor environments. Guidance for hydrogen generators that also provide oxygen used for industrial and commercial applications is provided in this document, however additional considerations may apply. The following are excluded from the scope of this document: residential hydrogen generators that also supply oxygen as a product; hydrogen generators that can also be used to generate electricity, such as reversible fuel cells (refer to IEC 62282-8-101, IEC 62282-8-102 and IEC 62282-8-201); hydrogen generators that use solid oxide electrolyte (refer to IEC 62282-8-101 and IEC 62282-8-201).