The cable routing of the explosion-proof socket switch combination box must strictly follow the core principles of safety, reliability, orderliness, and easy maintenance. The specific methods are as follows:
1、 Preparation before wiring
Environmental inspection: Ensure that there are no open flames or sources of static electricity in the work area, good air circulation, and compliance with explosion-proof requirements.
Material preparation: Select cables, terminal blocks, seals, and other materials that meet explosion-proof standards, and verify if the specifications and models match.
Tool preparation: Prepare specialized explosion-proof tools such as wire strippers, screwdrivers, and multimeters to ensure reliable tool quality.
2、 Cable introduction and fixation
Cable entry:
Use explosion-proof cable connectors or explosion-proof seals to guide the cables into the box, ensuring that the cables are not damaged.
After the cable passes through the gland, its insulation layer should be tightly held by the sealing ring and clamping device inside the gland, and the conductor should be inside the gland.
The cable sheath on the inside of the gland should be kept at a certain length to prevent stress from being directly transmitted to the terminal block.
Cable fixation:
After the cable enters the box, it should be immediately fixed to the box structure or installation rail with nylon zip ties or specialized wire clips to eliminate the stress of the cable's own weight and external pulling force on the terminal connection points.
The fixed points should be evenly distributed to avoid loose or sagging cables.
3、 Space layout and zoning routing
Partition planning:
Natural "functional areas" should be formed inside the box, such as power input area, branch output area, terminal block area, and component installation area.
The lines should be laid according to functional zones to avoid crossing and confusion.
Principle of direction:
The main lines should be laid along the perimeter of the box or pre-set cable trays, achieving a "horizontal and vertical" alignment and forming a neat "skeleton".
Multiple wires should be parallel and folded together, tied with zip ties to avoid loose crossing and forming a 'chicken nest line'.
Sense of level:
Arrange the main circuit lines with high power and thick wire diameter at the bottom or outer side, and arrange the control, signal and other small section lines at the top or inner side.
The wiring between the main air switch and each branch air switch inside the box usually goes on the left side, and the outgoing line of the distribution box usually goes on the right side.
4、 Terminal connection
Requirements for crimping:
For multi stranded copper core wires, it is necessary to use copper wire connectors (wire ears) that match the wire diameter and use professional crimping pliers for crimping.
Ensure that the crimping is firm and will not loosen due to vibration or thermal expansion or contraction.
Tightening torque:
Use a suitable screwdriver or socket to tighten the terminal screws to the specified torque, ensuring minimal contact resistance and preventing overheating due to poor contact.
After tightening, a slight tensile test should be conducted to ensure reliable connection.
Reserved margin:
The wire should have appropriate curvature or margin at the terminal to prevent damage to the wire core caused by pulling the terminal during maintenance.
5、 Safety distance and grounding
Safety distance:
Adequate air distance must be maintained between exposed conductors of different potentials (such as phase lines and ground lines) to prevent air breakdown and arc formation.
Adequate distance must be maintained between conductors of different potentials along the surface of the insulation material to prevent the formation of leakage marks or even short circuits under humid and polluted conditions.
When the spacing may be insufficient, measures such as installing insulation partitions, sleeves, or using wires with higher insulation levels must be taken.
Grounding requirements:
The yellow green dual color ground wire must be directly and continuously connected to each device that requires grounding (such as lighting fixtures on doors, metal enclosures) and a dedicated grounding busbar.
The grounding wire should be connected in a "radial" manner, that is, it should be led out from the grounding busbar to each grounding point separately. It is strictly prohibited to connect multiple grounding terminals in series on one line.
The contact surface of the grounding terminal should have the paint or oxide layer removed to ensure good metal contact, and a spring washer should be installed to prevent loosening.
6、 Inspection and maintenance after wiring
Visual inspection:
Refer to the drawings, check if the wire numbers are correct, if the wiring is neat, if the colors are standardized, and if the grounding is reliable.
Check if there are any cut wire ends, metal shavings or other conductive foreign objects inside the box, which must be cleaned.
Torque review:
Spot check the tightening torque of key terminals (such as main circuit and grounding terminals) to ensure reliable connection.
Insulation resistance test:
Measure the insulation resistance between conductors and between conductors and ground using a megohmmeter to ensure compliance with regulatory requirements (usually ≥ 1M Ω).
Regular maintenance:
Regularly inspect and maintain the explosion-proof socket switch combination box to ensure that the wiring is secure, free from looseness or aging.
Timely replace damaged cables, wiring terminals, and other components to ensure safe operation of the equipment.