20160130 One question per day

What are the measures to prevent cable fires? Answer: (1) Use flame-retardant cables ； (2) Use fire-resistant cable trays ； (3) Use fire-resistant coating ； (4) Install fire-resistant partitions and fire barriers at cable tunnels, mezzanine exits, etc ； (5) Aerial cables should be kept away from oil pipelines and explosion-proof doors; otherwise, local conduit installation or thermal and fire protection measures should be taken.

What are the measures to prevent cable fires? 1. Use flame-retardant cables； 　　2 Use fire-resistant cable trays ； 　　3 Use fire-retardant coating ； 　　4 Fire-resistant partitions and fire barriers should be installed in cable tunnels, mezzanine exits, and similar locations ； 　　5 The overhead cables should be kept away from oil pipelines and explosion-proof doors; otherwise, local conduit installation or thermal and fire protection measures should be taken.

What are the measures for cable fire protection? The measures for cable fire protection include: (1) using flame-retardant cables; (2) employing fire-resistant cable trays; (3) using fire-resistant coatings; (4) installing fire barriers and partitions in cable tunnels, mezzanine exits, etc.; (5) overhead cables should be kept away from oil pipelines and explosion-proof doors, or otherwise local conduit installation or thermal/fire insulation measures must be taken.

Answer: Cable fire protection measures: 1. Select cables that meet the requirements for thermal stability. The cable selected is capable of meeting the heating requirements under normal conditions for a long period at its rated load, and it also maintains thermal stability during short circuits, thereby preventing the cable from overheating and catching fire. 2. Prevent overloading. Cables should generally not be operated beyond their rated load; if operation at an overload level is necessary, the duration of such overload operation must be strictly controlled to prevent overheating and cable fires. 3. Comply with the relevant regulations regarding cable installation. Cables should be laid as far away from heat sources as possible, and should avoid running parallel to or intersecting with steam pipes. If they do run parallel to or intersect with such pipes, a specified distance must be maintained, and insulation measures must be taken. It is prohibited for any cables to be laid parallel above or below heat pipes ； In the tunnels or ditches of some pipelines, it is generally avoided to lay cables; therefore, insulation measures must be taken when operation is required ； The installation of overhead cables, especially plastic and rubber cables, is protected from the effects of heat through insulation measures ； For cable laying, the parallel or crossing distances between cables, as well as between cables and heat pipes or other types of pipes, and between cables and roads or railway structures, must comply with relevant regulations. In addition to the requirements applicable to cables, a leftward curvature should be provided to prevent the cables from contracting too much during winter operation, which could otherwise cause strain on the cables and damage to their insulation. The cable should be bent such that a minimum radius of curvature is maintained; excessive bending can damage the cable’s insulation ； Cable tunnels should avoid having joints, as cable joints represent the weakest points in the cable’s insulation. In order to prevent cable short circuits, junction boxes must be installed in the middle of the tunnel, as well as in the fire-resistant panels surrounding other cables. The relevant regulations are in place to prevent cable overheating and insulation damage, as well as to ensure all effective actions are taken for fire safety. 4. Conduct regular inspections. Power cables should be inspected regularly, and the temperature of the air as well as that of the cables should be measured periodically in the cable trenches; in particular, temperature records of large-capacity power cables and fiber optic cable splice boxes are important. Defects are identified and addressed through timely inspections. 5. Closely seal the cable openings, and install fire doors and partitions at those openings. To prevent cable fires, it is necessary for cables to pass through walls, floors, shafts, and cable trays in order to reach control rooms, cable ladders, control cabinets, and instrument panels. In cases where there are cable openings, the switch cabinets must be sealed properly (so that they are airtight, smooth, and aesthetically pleasing, and that the cables are not damaged). A long cable tunnel and its branch intersections should be equipped with fire separation walls and fire doors. Under normal conditions, the doors of cable trenches or openings should be closed; thus, in the event of a fire involving cables, it is possible to isolate or limit the area of combustion and prevent the fire from spreading. 6. Jute for the outer sheath of underground cables. Buried cables are covered with a layer of jute impregnated with asphalt or similar materials, which provides protection for them. When such cables are placed in cable trenches, tunnels, or shafts, this outer layer of jute impregnated with asphalt must be removed in order to reduce the risk of fires from spreading. At the same time, the cable trench covers should be properly in place and fully covered, to prevent slag from getting into the cables and reducing the likelihood of fires. 7. Maintain cleanliness and proper ventilation in the cable tunnels. Cable tunnels or passages should be kept clean; the accumulation of trash and debris is strictly prohibited. Water and finished oil in these tunnels and channels must be removed promptly ； During normal operation, provide proper ventilation for cable tunnels and passages. 8. Ensure that cable tunnels or channels are well-lit. In cable layers, the lighting or channels within cable tunnels are usually in good condition, and specialized ladders that allow access to the upper and lower parts of the tunnels and grooves are required.

(1) Use flame-retardant cables； (2) Use fire-resistant cable trays ； (3) Use fire-resistant coating ； (4) Install fire-resistant partitions and fire barriers at cable tunnels, mezzanine exits, etc ； (5) Aerial cables should be kept away from oil pipelines and explosion-proof doors; otherwise, local conduit installation or thermal and fire protection measures should be taken.

What are the measures to prevent cable fires? The answers are as follows: (1) Use flame-retardant cables ； (2) Use fire-resistant cable trays ； (3) Use fire-resistant coating ； (4) Install fire-resistant partitions and fire barriers at cable tunnels, mezzanine exits, etc ； (5) Aerial cables should be kept away from oil pipelines and explosion-proof doors; otherwise, local conduit installation or thermal and fire protection measures should be taken.

The cable is buried underground, covered with yellow sand, and then topped with a cement cover plate.

　1 Use flame-retardant cables； 　　2 Use fire-resistant cable trays ； 　　3 Use fire-retardant coating ； 　　4 Fire-resistant partitions and fire barriers should be installed in cable tunnels, mezzanine exits, and similar locations ； 　　5 The overhead cables should be kept away from oil pipelines and explosion-proof doors

1 Use flame-retardant cables； 　　2 Use fire-resistant cable trays ； 　　3 Use fire-retardant coating ； 　　4 Fire-resistant partitions and fire barriers should be installed in cable tunnels, mezzanine exits, and similar locations ； 　　5 The overhead cables should be kept away from oil pipelines and explosion-proof doors; otherwise, local conduit installation or thermal and fire protection measures should be taken.

1 Use flame-retardant cables； 2 Use fire-resistant cable trays ； 3 Use fire-retardant coating ； 4 Fire-resistant partitions and fire barriers should be installed in cable tunnels, mezzanine exits, and similar locations ； 5 The overhead cables should be kept away from oil pipelines and explosion-proof doors; otherwise, local conduit installation or thermal and fire protection measures should be taken.