20A solid core current transformer, high accuracy is designed for use with a GLS-EM-MCU Crestron Green Light Power Meter Control Unit. Current transformers are vital to metering power. Current transformers are vital to metering power. Crestron offers various split core models that work with 600, 400, and 200 Amp feeds; these devices clamp around main feeds. Solid-core models exist for 50 and 20 Amp circuits, the wire must be routed through the closed loop of the core.