This technical report outlines principles which are intended to beused as the basis for determining the requirements for connectinglarge distorting loads (producing harmonics and/or interharmonics)to public power systems. The primary objective is to provideguidance for engineering practices which will ensure adequateservice quality for all connected consumers.Since the guidelines outlined in this report are necessarily basedon certain simplifying assumptions, there is no guarantee that thisapproach will always provide the optimum solution for all harmonicproblems. The recommended approach should be used with flexibilityand judgment as far as engineering is concerned, when applying thegiven assessment procedures in full or in part.