In electrical wiring work, the electrician is supplied with a layout of wiring installation and an installation plan initially. On the basis of the layout and installation plan, the electrician should draw the circuit and wiring diagrams before the commencement of work for systematic execution of the work.The terms used in wiring installation drawings are explained here.
- Layout diagram: Some customers give their requirements
in writing. But a few can give them in the form of a layout
diagram to the electrician. In the case of a written
requirement, the electrician will prepare a layout diagram
and then get the approval of the consume The layout diagram (Fig 1) is a simplified version of the
wiring diagram. Its purpose is to inform the reader quickly
and exactly, what the circuit is designed for without giving
any information on the circuit itself.This type of layout diagram is used for preparing architectural diagrams, plans, etc. of a building. In a layout diagram, it is necessary to indicate with symbols details like whether the wiring is on the surface or concealed, and the run `up' or `down', the number of wires in run, dimensions, and accessories with appropriate I.S. symbols. Normally the layout plan is drawn and then the wiring diagram. After completion of the wiring diagram, the number of cables to be run in each cable run and the size of conduit or batten are estimated. With the help of the distance marking in the layout plan, the estimation of cables, could be made.
- Installation plan (Fig 2): This plan shows the physical
position of accessories in an installation, and also gives the
final appearance of the installation. It may not be possible
to draw the installation plan for the entire layout diagram.
But it can be restricted to a small part of the installation to
highlight the type of conduit, accessories, spacing of
gutties, clamps etc.
- Circuit diagram (Fig 3): This shows the schematic
connections of the circuit for a specific task in the simplest
form, incorporating the graphical symbols.
The purpose of a circuit diagram is to explain the function of the various accessories in the circuit. Fig 3 is an example of a circuit diagram for controlling a lamp from two different places. - Wiring diagram (Fig 4): This is the diagram in which the
position of the components in the diagram bears a
resemblance to their actual physical position.The wiring diagram may not have distance marking. Use of the wiring diagram along with the layout diagram enables the technician in the initial stages of the planning to specify/estimate the required type, size and length of the cables, and also to decide on the vertical, horizontal and ceiling runs of the cable. The wiring diagram is of great use to test and rectify faults in the installation during maintenance work. Fig 4 also shows the wiring plan for controlling a lamp from two different places with their actual locations. For his own good and to facilitate quick location of faults at a later stage, the customer should insist on the electrician giving him a copy of the wiring diagram soon after the completion of wiring. The electrician should make it a point to do so.
- B.I.S. Regulations and the N .E. code pertaining to wiring installations The wiring installation shall generally be carried out in conformity with the requirements of the Indian Electricity Act 1910, as updated from time to time and the Indian Electricity Rules 1956, framed thereunder, and also the relevant regulations of the electric supply authority of the concerned area (State Government). To govern the installation of electrical wirings in buildings, with particular reference to safety and good engineering practice, the Indian Standard is published. The following are some of the extracts of B.I.S. (Bureau of Indian Standards) regulations pertaining to wiring installations. All the B.I.S. regulations are recommended by the National Electrical Code (NEC).
- B.I.S. regulations pertaining to wiring installations Wiring: Any one of the following types of wiring may be used in a residential building.
- Tough rubber-sheathed or PVC-sheathed or batten wiring.
- Metal-sheathed wiring system
- Conduit wiring system: a rigid steel conduit wiring b rigid non-metallic conduit wiring
- Wood casing wiring
- Fittings and accessories: All fittings, accessories and appliances used in wiring installations shall conform to Indian Standards. (I.S. mark) The system should provide easy access to fittings for maintenance and repair, and for any possible modification to the system. Modifications to the system shall be done only by licensed electrical contractors, licensed under the Indian Electricity Rules