Ground fault circuit interrupter switches off

The RCD can compare the amount of current flowing in and out. If the sum is intact, the current flowing in must be as high as the current flowing back, whereby the sum of the currents of the neutral conductor and phases must be zero. If this is not the case, the RCD disconnects the circuit, it "pops out". If L1, L2 and/or L3 are connected after the RCD and the neutral is connected before it, the RCD will notice a difference between the current flowing back and forth. Make sure that L1, L2, L3 and the neutral are connected after the RCD.