EPC Services were comissioned to determine the cause of a major VT failure on HS1 by Network Rail CTRL. Although a number of companies had tried to establish the cause of the problem EPC Services were able to trace the fault after one days investigation to a bonding design defect. The cost of the investigation was at a fraction of the cost of the other studies conducted by our competitors. The corrective action was undertaken allowing the Ebbsfleet connection to be comissioned on time allowing electrified domestic stock to to Ebbsfleet International.