The Cable Core Identifier is designed to  establish the phase rotation in an un-energised  three phase H.V. Cable. Prior to jointing.  This in expensive tool is very easy to use and effective, using three coloured LEDs to confirm correct connection.  The Receiver is connected at the remote end, and  continuity between phases is checked by changing the coloured crocodile connectors in accordance with the written instructions on the Transmitter.When all three LEDs light the phase connection is correct.