On several of our cameras a horizontal line appeared after we rerouted wiring and installed a static switch in our access control room's intrusion panel. I suspect it is interference from the power cable running along side the siamese cables in the wiring gutter overhead. The power cable runs approximately 10 feet inside the gutter containing video and access control cabling. Is the 10 ft distance enough to cause this type of interference? Can shielding be added to the existing power cord or is this even the likely cause? If so are there any suggested methods for adding shielding? The interference began the second the static switch was connected. The cameras affected are 6 of a 16 channel encoder, and we have switched a single camera to an unaffected encoder with no change. The horizontal line appears in the same position of displayed video for all of the affected cameras.