In electrical engineering, the commonly used wire conduits are mainly metal and plastic wire and tube, and their classification is also different.
The following symbols are commonly used for the marking of pipes in engineering drawings:
SC: welded steel pipe; JRC: water gas steel pipe; MT: black iron wire pipe; JGD: sleeved galvanized iron pipe; KBG: thin-wall galvanized iron pipe; PC\PVC (flame retardant pipe): PVC hard wire pipe; KPC: PVC plastic corrugated wire tube
KBG, JDG is a variant of thin-walled electric wire tube, which belongs to the industry standard labeling, not the national standard, and SC is not the same thing. SC is the welded pipe on the specification, and it is thick-walled, and the wall thickness is usually not less than 3mm.

 the metal wire conduit
1. In construction engineering, metal conduits can be divided into thick-walled conduits and thin-walled conduits according to the thickness of the pipe wall.

According to the steel pipe forming process, it can be divided into welded steel pipes and seamless steel pipes.
a. Welded steel pipe is a welded pipe, which is cut into narrow steel bars by steel strips, and then cold-wrapped into a tubular shape by a mold. Then, a special welding machine then welds a pipe joint, the outer weld seam is polished, and the inner burr of the general welded pipe is not Only the precision welded pipe is used to hit the inner burr.
b. Seamless steel pipe is hot drawn into a tubular shape with a cylindrical steel ingot, so it is invisible that the weld is subjected to a higher pressure than the welded pipe.
2.the connection of the catheter
Thick-walled wire ducts are generally connected by a ferrule. Thin-walled wire ducts are usually connected by tight-fitting or crimping. In the case of equipotential grounding, in addition to the compact type, the other methods need to be bridged with copper core cords. Ground.

plastic wire conduit
The plastic pipes used as wire conduits mainly include PVC, PE, high-density polyvinyl chloride pipes, etc., and are mainly used for small-diameter pipes. Plastic wire tubes are generally used for temporary construction or outdoor use, and should be waterproof when used outdoors.
the hose
The hose is generally used at the end of the equipment. Generally, the electrical engineering is wrapped with a metal hose. The softness is better. The specification specifies that the length of the end in the power engineering does not exceed 0.8m, and the length of the hose in the lighting project does not exceed 1.2m.

Pipe fittings introduction
JDG accessories
The metal wire conduit is directly made of high quality pipe material for the joint, and is double-sided galvanized for pipe and pipe connection. There is a rolling positioning groove in the middle of the pipe joint, and the taper formed can make the pipe insert tightly positioned, and the sealing property is good. When the dark coating is applied, the mortar and even the water are not easy to enter the pipe; and the groove depth is consistent with the rear of the pipe wall. After the catheter is inserted, the inner wall is smooth and does not affect the threading. There is one (32 or more) with a fixed threaded hole near the two ends of the pipe joint. The length of the threaded hole is larger than the wall thickness of the pipe joint, and is formed by stamping from the inner wall of the pipe to the outer wall of the pipe to form a protrusion and then tapping. The increase in the number of turns makes the tight connection more secure. The set screw is specially made, it is hexagonal and has a "+", word slot, and the other end is in the shape of a socket. Close to tighten the set screw until the "neck" is twisted, so that the catheter and the joint are integrated, no need to do it again. Cross the ground wire. There are six specifications and they are used with the corresponding catheter.
The threaded joint is made of high quality pipe and is galvanized on both sides for pipe and box connection. At one end that is connected to the conduit, there is one (32 or more) threaded holes with set screws, and the set screws and threaded holes are the same size as the straight pipe joints. The end connected to the wire box has a claw-shaped lock nut and a hexagonal lock nut to clamp the wall of the wire box, and no need to cross the ground wire. There are six specifications and they are used with the corresponding catheter.
The special pipe bender is molded by casting and then precision machined. The specifications are $16, 20, and 25, which are necessary tools for bending the corresponding pipe diameter on site.
KBG accessories
Straight pipe joints are made of high-quality pipe for pipe and pipe connection; there are U-shaped grooves with the same depth and wire conduit wall thickness. There are five specifications, each of which is used with the corresponding specification of wire conduit.
Elbow joint: It is rolled and formed with high quality pipe, which is 90° angle. There are two types of four-fold bending and six-fold bending, and the bending radius is 4 and 6 times of the pipe diameter, respectively.
Threaded joint: It is processed and formed by high quality pipe, and the pipe is connected with the box. There are two types, one type and one type, each of which has five specifications and is used with the corresponding specifications of the catheter.