Building Wiring Calculations

In this chapter it is required to plan the distribution system of the residential area. The planning of this area starts from inside the individual flats of the buildings.

The various types of loads in the house like lighting, normal sockets (N.S), power sockets (P.S) and load break switches (L.B.S) are estimated according to the standard forms. The feeding circuits are defined and the main wiring c.s.a. are calculated.

The mains wiring is generally built using insulated copper cables. The choice of conductor material is a compromise among electrical properties, mechanical properties, and price. From the start, copper has been the material of choice for household branch circuits.

Aluminum is softer than copper and weaker, and a poorer electrical conductor, so is not widely used in small sizes for home wiring. Aluminum cable material is sometimes used (for economical reasons) for thick mains feeder cables coming from electrical utility to the mains distribution panel.

The ratings of the sub-circuits' miniature circuit breakers (M.C.B) and the main circuit breaker of the flat or the villa as well as energy meter are selected.

Any house that has been properly wired will have a circuit breaker panel used to shut circuits off in case they draw too much current. It is the current capacity of circuit breaker (in amperes) that determines how much current a circuit can supply. In case of an overload or a short-circuit on that circuit, the breaker trips and automatically shuts off power to that circuit. Ground fault circuit breakers offer protection against more than just overloads.

After the load of the flat is being calculated, the diversified estimation of the total load of the building is made. The buildings are fed from distribution boxes via cables of suitable sizes, forming a part of the low voltage distribution network. The distribution boxes are fed from 11 KV/380 V distribution transformers, preferably in loops, to secure the continuity of supply to the distribution boxes and hence to the buildings.

The distribution transformers are located in the appropriate sites and connected in loops to the 11KV Distribution points and the 66/11KV substation.

   

Detailed calculations and planning of the 380V low voltage distribution network, the 11KV medium voltage network as well as details of the 66/11KV substation feeding the area, are presented in the following chapters. Before this, the principles of lighting and wring are summarized in the following sections.