Harmonised standards are technical standards such as ISO norms that are developed by groups across the EEA. These norms are considered to be state of the art and compliance against them means your product meets all the essential safety requirements. Notified bodies traditionally only use harmonized standards unless specifically asked not to by the client (for example if they want to use a non-harmonized but still valid technical standard). Harmonization is performed at the request of the commission by a European standards body (i.e. CEN, ETSI or CENELEC). For RCD 2013/53/EU most harmonized standards are directly transposed from ISO norms however CEN does at times develop, where appropriate, additional norms (i.e. EN 60092).
When a declaration of conformity is issued using harmonised standards to prove compliance against the applicable directive, a presumption of conformity is bestowed upon the product. Having a presumption of conformity means it is far easier to demonstrate compliance with the essential requirements of a directive. Using a harmonised standard means a national authority may ask what steps you have taken to ensure compliance and whether these were enough – with harmonised standards they are more likely to ask whether you meet the requirements of the specific standard you have applied which is much easier to prove.
The harmonized standards for RCD can be found using the search engine and table below: