Brianl703, I've done hipot and lightning transient testing on random NIC cards and products in the past. I've seen good and bad ethernet isolation. In the IEC/UL 60950 world, and as confirmed by TR 62102, ethernet is SELV. It is usually only being isolated from other SELV circuits. The insulation is required to meet requirements of Functional Insulation. Per clause 5.3.4 of xx60950 (or 60950-1) this means the insulation must either meet creepage and clearance, pass a 500 VAC hipot, or pass a short circuit test under normal conditions. I think the reason there are some hi-isolation ethernet device out there is for use in isolating ethernet/SELV from POTS/TNV3 circuits.
