An electrical system, comprising: a first electrical connector suitable for being coupled to an electrical panel; a second electrical connector suitable for being coupled to a testing device that is configured to test a component coupled to the electrical panel; and a retaining harness assembly that removably connects to the first and second electrical connectors (100, 102) to maintain a secure mating relationship between the first and second electrical connectors (100, 102), wherein the retaining harness assembly comprises: a rear wall connected to opposed lateral walls, wherein a connecting chamber is defined between the rear wall and the lateral walls; a lower ledge separated from an upper ledge by a flange-receiving slot, wherein a flange of the second electrical connector is received and retained within the flange-receiving slot, wherein the lower ledge exerts a first retaining force into the flange; wherein said retaining harness assembly further comprises a retaining collar that secures around a portion of a backplane of the first electrical connector and abuts into a torque ring of the first electrical connector, said torque ring arranged to provide a secure connection between the first and second electrical connectors when torqued or otherwise rotated, wherein the retaining collar exerts a second retaining force into the torque ring, wherein the retaining collar includes one or more first recessed areas configured to conform to a portion of an outer surface of the backplane, and the opposed lateral walls are configured to be deflected into an open position in order to remove the retaining harness assembly from the first and second electrical connectors (100, 102). a first electrical connector suitable for being coupled to an electrical panel; a second electrical connector suitable for being coupled to a testing device that is configured to test a component coupled to the electrical panel; and a retaining harness assembly that removably connects to the first and second electrical connectors (100, 102) to maintain a secure mating relationship between the first and second electrical connectors (100, 102), wherein the retaining harness assembly comprises: a rear wall connected to opposed lateral walls, wherein a connecting chamber is defined between the rear wall and the lateral walls; a lower ledge separated from an upper ledge by a flange-receiving slot, wherein a flange of the second electrical connector is received and retained within the flange-receiving slot, wherein the lower ledge exerts a first retaining force into the flange; wherein said retaining harness assembly further comprises a retaining collar that secures around a portion of a backplane of the first electrical connector and abuts into a torque ring of the first electrical connector, said torque ring arranged to provide a secure connection between the first and second electrical connectors when torqued or otherwise rotated, wherein the retaining collar exerts a second retaining force into the torque ring, wherein the retaining collar includes one or more first recessed areas configured to conform to a portion of an outer surface of the backplane, and the opposed lateral walls are configured to be deflected into an open position in order to remove the retaining harness assembly from the first and second electrical connectors (100, 102).