Came across a situation in which the project engineer has a differential protection scheme that measures the incoming 13.8Kv to a transformer and then is measuring the (secondary) 480V bus (in some ratio I assume) for the differential protection which appears fine for the equipment in the substation. Then he used the same CT's C200, 0.3B0.1 (.3% @ .1 ohm allowable burden) for remote located transformers and 480V switchgear containing the low voltage CT 350 feet away from the 13.8Kv CT. Seems the remote transformers would need C200,0.3B0.5 or better to be able to maintain a Z that will accurately trip or not have a false trip. This unit is stretched thin on incoming power as it is and seems a critical portion of the new substation protection. I'm very uncomfortable with this situation. Guru's thoughts?