Our task was to study European legislation in the field of low power energy consumption which is covered by the Directive of European commission 1275/2008 and 801/2013 in conjunction with the relevant European and consequently Slovenian standard for low power measurement SIST EN 50564. From it we extracted the main problems and requirements and compared it to each other. We focused mainly on suitable conditions for testing, suitable measurement instrument selection, correct connection of the measuring instrument, suitable selection of method for measurement and measurement uncertainty calculation. Our main assumption was, that this parameters significantly affect low power measurement. Furthermore we compared influences of those parameters on final measuring result for a selected load in three different energy states (stand by mode, off mode, active mode). In the analysis we compared all the results and identified their compliance with the standard.