Front-Panel Visible Wiring Standards for Electrical Control Panels
Front-panel visible wiring: During manual wiring (not using templates or molds), wiring must be straight, neat, closely attached to the mounting surface, rationally routed, and with secure connections that facilitate maintenance.
Wiring channels should be minimized as much as possible. Within the same channel, bottom-layer conductors shall be grouped by main and control circuits, arranged in a single-layer parallel dense layout or bundled, and kept closely attached to the mounting surface.
Conductor length should be as short as possible. Horizontal aerial spans are permitted—for example, between two coil terminals or between main contact terminals—provided a certain amount of slack is left, and such conductors need not be tightly attached to the mounting surface.
Conductors on the same plane shall be aligned at the same height or depth and must not cross. If crossing is unavoidable, a horizontal aerial span may be used, but only if it constitutes rational routing.
Wiring must be horizontally level and vertically straight, with direction changes made at 90° angles.
If upper and lower contact points are not vertically aligned, diagonal wiring shall not be used.
When connecting conductors to terminal blocks or studs, the insulation layer must not be pinched, reverse loops are prohibited, and exposed copper shall not exceed 1 mm. Additionally, the spacing between conductors at different connection points of the same component or same circuit shall remain consistent.
No more than two conductors shall be connected to a single terminal of an electrical component. Generally, only one conductor is allowed per terminal segment on a terminal block.
During wiring, the conductor core and insulation must not be damaged.
When conductors of different cross-sectional areas are used, those with larger cross-sections shall be placed in the lower layer, and those with smaller cross-sections in the upper layer.
When routing multiple conductors (main power circuits), they shall be arranged so that the entire group lies on the same horizontal or vertical plane.
Coding sleeves may be omitted if the wiring is simple.
Wire color coding:
Protective earth (PE) conductors must be green-and-yellow.
Neutral (N) and mid-point (M) conductors in power circuits must be light blue.
AC or DC power circuits shall use black conductors.
AC control circuits shall use red conductors.
DC control circuits shall use blue conductors.
Interlock conductors in control circuits that remain live when the external control circuit is disconnected shall be orange or yellow.
Circuits connected to the protective conductor shall use white conductors.
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