The over-voltage protection component ground reference must be the same as the PHY ground reference and should not be the same ground reference as a grounded RJ45 connector or connected directly to earth chassis. This would remove the isolation barrier provided by the coupling transformer and not comply with the IEEE 802.3 isolation requirements. This solution shown here provides a higher ESD resistibility solution 20kV Vs. 12kV from previous slide and a higher surge level (10A, 8/20µS Vs. 4.5A, 8/20µS) for applications located in colder climates with higher ESD being likely.