Seaward 3 phase adaptors 5 star tpa series seaward 391a920 which seaward pat tester is best for you help me decidethe seaward 391a920 is a 3 phase adaptor which will allow earth continuity and protective conductor current measurements to be carried out on 3 phase machinery as required by the iee code of practicethe 16a adaptor has been designed and manufactured for use with the primetest 250 pat tester it will quickly and easily measure the protective conductor current without removing