Twelve wiring rules for cable tray: when selecting cable tray for indoor wiring, the cable shall not have jute or other combustible material outer sheath. When the cable tray is installed horizontally, the best span should be selected for support according to the load curve, and the span is generally 1.5 ~ 3M When laying straight, the interval between fixed points shall not be greater than 2m. When cable tray wiring is selected in places with corrosion or special humidity, corresponding protection methods shall be adopted according to different corrosive media, and plastic sheathed cables shall be selected. When several groups of cable trays are installed in parallel at the same height, maintenance and overhaul intervals shall be considered between adjacent cable trays.
The cable can be laid on the cable tray without interval. The filling rate of the cross section of the cable in the cable tray: the power cable shall not be greater than 40%; The control cable shall not be greater than 50% Generally, the height of the cable tray from the ground when it is installed horizontally shall not be less than 2.50M. When it is installed vertically, the part below 1.80m from the ground shall be maintained with a metal cover plate, but when it is laid in the special electrical room, it shall be outside. The cable tray shall not be installed above the corrosive gas pipeline and heat pipeline and below the corrosive liquid pipeline, otherwise anti-corrosion and heat insulation measures shall be adopted.) Dual power cables, strong current and weak current cables that supply power to class I load in the same path. If it is constrained by conditions and needs to be installed on the bridge on the same floor, the partition plate shall be used for separation.
1. Cable tray wiring is applicable to places with large or concentrated cables.
2. When cable tray wiring is used in places with corrosion or special humidity, corresponding protective measures shall be taken according to different corrosive media, and plastic sheathed cables should be selected.
3. When the cable tray is laid horizontally, the height from the ground shall not be less than 2.5m, and when it is laid vertically, the height from the ground shall not be less than 1.8m. In addition to laying inside and outside the special electrical room, when the requirements cannot be met, metal cover plate shall be added for protection.
4. When the cable tray is laid horizontally, the best span should be selected for support according to the load curve, and the span should be 1.5 ~ 3M. When laying vertically, the distance between fixed points shall not be greater than 2m.
5. When the cable tray is laid in multiple layers, the distance between layers shall comply with the following provisions:
1) The distance between power cable trays shall not be less than 0.3m;
2) The distance between telecommunication cable and power cable bridge shall not be less than 0.5m. When there is a shielding cover plate, it can be reduced to 0.3m;
3) The distance between control cable trays shall not be less than 0.2m;
4) The distance from the upper part of the bridge to the ceiling, floor or beam and other obstacles shall not be less than 0.3m.
6. When two or more groups of cable trays are laid in parallel at the same height or up and down, a maintenance and overhaul distance shall be reserved between adjacent cable trays.
7. Cables can be laid on the cable tray without distance. The ratio of the total cross-sectional area of the cable to the cross-sectional area in the tray shall not be greater than 40% for power cables; The control cable shall not be greater than 50%.