Electrical installation symbols First, the wire threading pipe generally has:
PVC pipe: PC20,
Welded steel pipe: SC20, galvanized steel pipe: SR buckled galvanized thin-walled electric wire pipe: KBG20 compact galvanized thin-walled electric wire pipe: JDG20
Second, electrical design and construction drawings commonly used line laying methods:
SR: Laying along steel wire trough
BE: Laying along the roof truss or across the roof truss CLE: laying along the column or span
WE: Laying CE along the wall: laying along the ceiling or ceiling
ACE: Laying in the ceiling that can enter the person BC: Darkly placed in the beam CLC: Darkly placed in the column WC: Darkly laid in the wall CC: Darkly placed in the ceiling
ACC: Dark coating is placed in the ceiling that cannot be accessed
FC: Darkly laid in the ground
SCE: laying in the ceiling, to wear metal pipe
First, the wire is shown in the tube
SC-welded steel pipe
MT-wire tube PC-PVC plastic hard tube FPC-flame retardant plastic hard tube CT-bridge MR-metal trunking M-wire cable CP-metal hose PR-plastic trunking RC-galvanized steel pipe
Second, the representation of the wire laying method
DB-buried TC-cable trench
BC-dark in the beam
CLC-dark in the column
WC-dark in the wall
CE-laying along the top of the ceiling CC-dark in the roof of the ceiling SCE-ceiling is laid inside the F-floor and under the floor SR- along the steel rope BE- along the roof truss, beam WE- along the wall
Third, the representation of the fixture installation CS-chain crane
CS-chain crane
DS-tube crane
W-Wall Mounting C-Ceiling R-Embedded S-bracket CL-column along steel wire trough: SR along the roof truss or spanning truss: BE along the column or spanning column: CLE wear welded steel pipe laying: SC laying wire pipe laying: MT Wear hard plastic pipe laying: PC wear flame retardant semi-rigid PVC pipe laying: FPC cable tray laying: CT metal wire trough laying: MR plastic trunking laying: PR laying with steel cable: M wearing PVC plastic corrugated wire pipe Laying: KPC wearing metal hose laying: CP direct burying: DB cable trench laying: TC wire laying location marking or traverse beam (roof) laying: AB dark coating in the beam: BC along or cross-column laying: AC dark laying In the column: CLC is laid along the wall: WS is laid in the wall: WC is laid along the ceiling or roof: CE is laid in the roof or roof: CC ceiling: SCE floor or under the ground: FC
(1) No bending pipeline does not exceed 30m;
(2) When there is a bend between the two junction boxes, no more than 20m;
(3) When there are two bends between the two junction boxes, no more than 15m;
(4) When there are three bends between the two boxes, no more than 8m;
(5) Four bends are not allowed between the two junction boxes of the dark piping
Third, the junction box
A junction box (first piping) is used behind each of the assembled electrical boxes (dark piping). The general distribution box of the junction box is the junction box. The terminal box generally has only the terminal block. There are no components, such as the branch junction box and the equipotential junction box. The ground terminal block is a terminal block of the ground terminal box. LEB is a partial equipotential connection. The box is generally small, the terminal board inside is also small, and the terminal is also rarely grounded. The jumper is used for the purpose of electrically assisting the common conduction potential of the broken interface between the segments of the bridge and the electric conduit. The current disconnecting card is not used for lightning protection grounding. It is generally used on the lead-in line of the artificial grounding pole. It is mainly used to disconnect the artificial grounding pole from the grounding grid when measuring the grounding resistance, so that it is convenient and accurate to measure this. Grounding of artificial grounding pole
Installation cable head production difference one, cable head according to the production of installation materials
Can be divided into heat-shrinkable (currently the most commonly used one), dry-pack and epoxy cast.
Nowadays, more than 70mm2 cables are generally heat-shrinkable. In fact, heat shrinkable heads are used. A heat shrinkable head ranges from tens of yuan to hundreds of yuan. The so-called "gloves" are shaped like gloves, and the outer protective layer of the cable is used. Peel off, put on the heat shrinkable head, and then use a blowtorch to heat it and attach it to the cable head (I won’t elaborate on the copper nose)
The dry bag type is made by winding a high-voltage self-adhesive tape and an electrical tape. Generally, temporary electricity is used more. Dry bag type below 70mm2.
Second, the difference between the cable head power cable head is divided into terminal head
And the intermediate joints are divided into indoor type and outdoor type according to the installation place. According to the cable head making materials, they are divided into three types: dry-pack type, epoxy-cast type and heat-shrinkable type.
1. Indoor dry-packaged power cable head, when the dry-pack cable head does not contain the "terminal box", it is called "simplified terminal", which is suitable for general plastic and rubber insulated low-voltage cables.
2. Indoor castable power cable terminal, castable cable head is mainly used for oil-impregnated paper insulated cable.
3. Indoor heat-shrinkable power cable terminal, heat-shrinkable cable head for 0.5 to 10.0kV XLPE cable and various cables.
Three, three cable head process differences:
Indoor dry-packaged power cable head: stripping protective layer and insulation layer, cleaning, wrapping insulation, pressure connection pipe and terminal block, installation and wiring.
Indoor pouring power cable terminal: sawing, stripping cleaning, inner shielding treatment, wrapping insulation, crimping lock pipe and terminal block, loading terminal box, batch casting, installation wiring.
Indoor heat-shrinkable power cable terminal: sawing, stripping cleaning, inner shield treatment, welding ground wire, crimping lock pipe and terminal block, heat shrinkable tube, heating forming, installation, wiring.
Fourth, the cable head (dry pack, heat shrink, pouring, cold shrink) under what circumstances
1) Dry packs. In some projects that are not demanding or to save money, low-voltage cable joints use more dry packs. Because the low-voltage electric field can be ignored, especially those installation companies use dry packs to save money. At present, there is no one in the domestic high-voltage dry-clad cable. In foreign countries, only 3M companies have dry-clad cable accessories (usually intermediate connectors).
2) Heat shrinkage, heat-shrinkable cable accessories are relatively expensive compared to dry packs, but it is economical to use heat-shrinkable cable accessories at 10KV and below. Generally, it is suitable for general power supply systems that do not require fire protection during new construction and construction.
3) Casting cable accessories, basically eliminated, mainly used on oil-immersed insulated cables, since the advent of heat-shrinkable oil-immersed cables, they have basically been eliminated. At present, low-voltage cables such as 3M also have cast cable connectors.
4) Cold-shrinkable cable joints, cable accessories that are currently being promoted, especially suitable for environments that prohibit open flame construction such as petrochemicals, and reduce human factors, and are safer. The disadvantage is that the price is relatively expensive.
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