Martindale pd690 690v proving device martindale marpd690 p the martindale pd690 is a 700v ac proving device designed to enable voltage indicators to be fully checked in compliance with health and safety recommendations using a voltage indicator without first proving it is working correctly could prove fatal p p this device is designed for indicators with 230v and 415 440v ac detection ranges such as the martindale vi13700 the proving unit is one of the few designs to check indica