This paper presents two novel three-phase common-mode (CM)/differential-mode (DM) noise separation networks, which are passive and active networks, to be used in electromagnetic compatibility conducted emission (CE) measurements of three-phase equipment. The passive network is analyzed theoretically, and a prototype is constructed and tested. Its evaluation is presented through frequency response measurements and CE tests performed on a three-phase motor drive and verifies that the network is capable of separating the CM and DM information in a CE measurement condition.