All CTs should have a marking for orientation. Some have a white dot, some have a label others have some other marking. Make sure you check with the manufacturer if you are not sure. For most CTs with wires, there will be a white and black wire. In most but NOT ALL cases the white wire is the HI side and goes to the HI input on the meter. Black to LO. Again if you are not certain check with the supplier. For CTs with terminals, there should be a label on the HI terminal.