1, zero row ground row phase line (L). The conductor that conveys electrical energy, and is not grounded under normal conditions.

2, neutral line (N). Connected to the neutral point of the system, and can play a role in conveying electrical energy conductor.

3, protective neutral (PEN). Both the protective line and neutral conductor.

4, power grounding point. The power supply can be grounded at a point (usually the neutral point) for grounding.

In general, the fundamental difference between the zero line and the ground is that one constitutes a working circuit, a protective role is called protective grounding, a back to the grid, a back to the earth, in electronic circuits, the two concepts are to be distinguished, in the formal situation of the two wires are required to be connected separately. Ground row needs to be connected to the distribution cabinet shell, ground through the leakage switch out of the zero line for the work of zero row. Simple cognitive method is that the straight copper row for the zero row, curved copper row for the ground row.