I want to use GLS-EM-MCU to check the current, voltage & power on the lighting circuit. I need to equip a GLS-EM-MCU, GLS-EM-CTI & GLS-EM-CT. As I only need to measure the lighting circuit and the lighting circuit is less than 20A, I will install a GLS-EM-CT-20A to track the data. It is a 3-phase MCB, is it a must to connect GLS-EM-CT to the MCB phase in this case? Because there are a lot of MCB, it will involve a lot of MCU, CTI & CT, also I only need to take the lighting circuit data, not overall system.