Common electrical equipment and materials problems and defense measures

1. Common electrical equipment and materials problems and defense measures

In the electrical installation project, the main electrical equipment and materials commonly used have the following problems: no product certification, production license, technical specification and test report; documents with high resistivity, low melting point, poor mechanical properties, and cross section less than nominal Value, insulation difference, large temperature coefficient, size (length per roll), etc.; low cable withstand voltage, low insulation resistance, poor corrosion resistance, low temperature resistance; many internal joints, poor insulation and core tightness; Lighting, socket box appearance is poor, geometric size can not meet the requirements, the thickness of the steel plate is not enough, affecting the strength of the box, corrosion resistance can not meet the requirements; various wire and tube wall is thin, the strength is poor, the quality of the galvanized layer does not meet the requirements, resistant Poor folding and so on.

2. Common problems in route laying and preventive measures

Frequent problems in the laying of lines include: the quality of steel pipes, wires and various junction boxes does not meet the requirements, the quality of the wires used is poor, the insulating layers of plastic insulated wires and the core wires are unshelled, the thickness of the insulating layer is uneven, the surface is rough, and the core wires are Insufficient diameter; the bending radius of the steel pipe is small, the bending quantity and the position of the junction box are improper, so that the insulation of the wire is difficult or the threading is difficult; the pipe mouth is not uniform, the horseshoe mouth appears; the pipe mouth has burrs, and the wire insulation layer is easily scratched; If the wire is too short or disorderly, the connection of the steel pipe is not strong; during the construction, there are phenomena such as missing, falling off and inconsistent pipe diameter of the steel pipe; the joint of the steel pipe, the connection between the pipe and the box (box) and the welding of the jumper. The grounding requirement is not met; the back wire or knot is formed during the threading process; the inner wire of the steel pipe has a joint or the inner steel pipe is too threaded; the wire connection method is improper, which brings unsafe factors, and the wire connection is inferior pressure wire cap Or do not weld, do not use rubber insulation tape and piping, use black iron pipe, do not brush oil, anti-corrosion treatment.

For the problems that often occur in line laying, we should proceed from the following aspects:

(1) Strictly control the variety, specifications, model and quality of piping and various wire boxes; strictly control the type, quality and insulation resistance of the wires, and must meet the design requirements and relevant technical standards. The insulated wire laid in the pipe shall have a rated voltage not lower than 500V. Wires should be laid out strictly in accordance with the design drawings, and should not be changed privately. The color of the wire should be configured according to the standard. Since the wires used in the tube are different, try to use plastic insulated wires of various colors to facilitate the wiring of electrical appliances. The diameter of the wiring pipe, the number of bends, the bending radius, and the arrangement of the junction box should ensure that the pipe can be threaded and changed without damaging the wire insulation. There should be no wrinkles, pockets and cracks in the bend of the pipe. When the pipe is dark, the bend radius of the pipe should not be less than 6 times the outer diameter of the pipe.

(2) When sawing the pipe, it should be done: the cut is vertical, not broken, the nozzle should be flattened and scraped, so that the nozzle is burr-free and smooth. If there is a horseshoe mouth, it should be cut off again. The length of the thread used at the junction with the junction box of the junction box shall not be less than 1.5 times the outer diameter of the tube; the length of the thread for the connection between the tube and the tube shall not be less than 1/2 of the length of the joint. 4 buckle, when the wire is connected, the length of the end of the connecting pipe should not be less than the length of the pipe joint plus 2 to 4 buckle. If the steel pipe protection is missing or falling off due to inadvertent operation, it should be filled in time; if the protection port does not match the pipe diameter, it should be replaced in time.

3. Distribution cabinet, junction box, ceiling fan hook pre-buried problems and countermeasures

The common problems in the pre-buried of the distribution box, junction box and ceiling fan are: the distribution box, junction box and hook are not set according to the figure, the coordinate offset is obvious, the row of lamp position and the ceiling fan hook box have large deviation; The cast-in-place concrete wall, the box inside the column, the box is not skewed, the recess is deeper, and the pipe mouth is too much into the box and the box. The box is not fixed firmly, it is moved by vibrating or the concrete slurry enters the box, and the box is not treated with anti-rust and anti-corrosion.

4. Switch, socket, lamp, ceiling fan installation problems and preventive measures

Common problems in the installation of switches, sockets, lamps and ceiling fans are: switches, sockets, lamps, ceiling fans installed in the same room, corridors, rows of lamps and ceiling fans horizontal and straightness deviation exceeds the specified value; fluorescent lamps replaced with wires Hanging chain, the lower wire is made of hard wire, the soft wire is not directly connected with the hanging chain fork, the wire is laid on the fluorescent lamp cover; the ceiling fan is buried and the junction box is too large, and the ceiling fan cover can not cover the hole of the junction box. The wire is exposed, the ceiling fan round steel is less than No. 10, the hook is not embedded, and the ceiling fan is fixed on the keel; the ceiling lamp directly mounted on the top plate is not equipped with a round table (square wood table) or the wooden table is of poor quality. The ceiling lamp mounted on the ceiling plate is not fixed frame, and is directly fixed to the top plate with self-tapping screws and the lamp cover that needs to be grounded is not grounded. In view of the above problems, the following precautions should be taken: the electrical pre-buried construction should be accurately positioned, especially the rows of lamps and ceiling fan junction boxes (ceiling fan hooks) should be accurately positioned; the hoisted fluorescent lamps should be according to the specifications and models required by the drawings. Set the position of the pre-embedded junction box on one side of the chain, not in the center of the lamp, so that the down-conductor of the fluorescent lamp can be woven together with the chain into the lamp. If there is no existing hole near the chain, it can be another. Drill a hole to make the wire into the lamp, do not lay the wire along the lamp cover and enter the lamp from the middle hole; the hook penetrates into the junction box and pre-processes it in the concrete floor, so that the ceiling fan cover can completely cover the junction box hole to avoid the wire exposure; If the lamp housing requires grounding, the wiring should be firm and reliable to ensure safety. Corrosion treatment, etc. For the problems that often occur in line laying, we should proceed from the following aspects: