1. The wiring trough should be smooth and have no sharp edges or corners, otherwise it needs to be protected by a protective sleeve.
2. The insulation of the internal wiring should be able to withstand the electrical stress that may occur in normal use.
3. When the sleeve is used as additional insulation for internal wiring, it should be fixed in a reliable manner.
4. Yellow-green two-color wires can only be used for grounding wires.
5. Aluminum wires should not be used for internal wiring.
6. Where multiple strands of wire are subjected to contact pressure, welding cannot be used unless there is a danger that the clamping device will not produce adverse contact during the year.