Open the hoist and measure each line separately with a multimeter. If there is a voltage to the ground, it is charged. No voltage is zero line! Generally, there are five wires, three of which are main circuits and the other two are control circuits. The other is the zero line of the control loop!
Three-line area
In order to make alternating current have convenient power conversion function, power transmission usually adopts three-phase four-wire form. The three heads of three-phase electricity are called phase lines, and the three tails of three-phase electricity are called zero lines or "zero lines". The reason why it is called neutral line is that at the moment of three-phase balance, there is no current flowing through the neutral line, and then it is directly or indirectly connected to the earth, and the voltage difference with the earth is close to zero.