The split core current transformer SCT007 allows module removal and refitting without open circuiting the primary current on any module with AC current input and reduces wiring costs. The split core concept allows fitting and removal without interfering with the load wiring. The option of using an external step-down CT will extend the range of any APCS module up to 40A. The SCT007 is itself a current transformer with a tail lead. Primary termination is achieved by means of one or more turns passed through the hole in the SCT007. Very high isolation levels are achieved as the primary conductors insulation level is added to the already high isolation level of the SCT007 (5kVrms). The SCT007 develops 0.325mA per Amp-turn in the secondary. The secondary can be safely left short circuit or open circuit. A combined linearity of 0.5% is available when the SCT007 is used with an APCS module