Electrical wiring needs expertise attention to every building projects. It directly related to the safety of human beings and utilities / equipment people handle.
The scope of electrical wiring shall cover supply, installation, testing and commissioning of all conduits and accessories, wiring, switches, socket outlets, spur outlets, junction boxes / pull boxes, GI pull wires, ceiling roses making connections etc.
This Electrical Construction Article gives comprehensive details of various installation methods, materials used in each installation methods used in building construction projects.
1. Conduit Wiring and Installation Methods
Conduit wiring is a system of wiring using tubes (pipes) either steel or PVC, to provide good mechanical protection for its conductors drawn inside the tubes. It also gives high degree of protection from fire hazards to its conductors. Conduit pipes will be installed on the surface of walls or roofs by means of saddles or hooks or concealed inside the wall or roof or floor.
2. Steel Conduits and Fittings In Electrical Construction
Steel Conduits and Fittings are made out of heavy / medium / light gauge steel. It uses different technologies for manufacturing these tubes depending its thickness and surface treatments.
3. Galvanized Rigid Steel Conduit
Galvanized Rigid Steel Conduit is recognized as the safest and most protective form of electrical raceway. It is important that steel conduit provides excellent physical / mechanical protection for wiring, and also acts as a ground shield, reducing EMI (electro-magnetic interference due to field emission) and minimizing any effect of external RFI (radio frequency interference). It is also act as an equipment ground conductor in a circuit, thereby reducing wiring requirements and simplifying installation. Steel Conduit can be installed indoors and outdoors, in dry locations or wet locations, exposed or concealed, in all atmospheric conditions and in hazardous locations.
4. Galvanized Electrical Metallic Tubing (EMT)
Galvanized Electrical Metallic Tubing (EMT) is similar to rigid steel conduit but is much lighter, weighing approximately 40 percent as much as rigid steel conduit of the same nominal size. EMT can be used for both exposed or concealed work provided, where during installation or afterwards, it is not subjected to severe physical damage. Use of EMT is restricted to systems not exceeding 600 volts and to non-hazardous locations except (Class II Division 2 NEC Section 502-4 (b). Galvanized Steel EMT installed in concrete on grade or above generally requires no supplementary corrosion protection. However, when installed in concrete below grade level and in contact with soil or cinders supplementary corrosion protection consisting of a protective coating of bitumastic or asphalt base paint or plastic is generally applied. According to NEC Section 348-1, EMT run in or under permanently moist cinder fill must be encased in at least two inches of cinder free concrete unless the conduit is at least 18 inches below the fill.