Built for 150A to 600A/333mV applications. Feature safe, low-voltage outputs (not current output ratio CTs) for indoor use only in 50 or 60 Hz circuits up to 600 Vac. Built-in burden resistor calibrated to output exactly 333.33 mVac. When the CT’s rated full-scale, the current flows through the conductor in the CT’s window opening. Can be installed without interrupting the circuit.