Following factors must be taken into consideration for electrical installation

Electrical networks in buildings serve the purpose of distributing the required power to the consuming point where it is used for different purposes.

Installations have to take care (i) of load requirements and supply limitation in a simple and economic manner ensuring at the same time full protection to human life and property by fire, (ii) To facilitate easy installation and repair or maintenance.

Necessity of conserving power to maximum extent, power factor compensation assumes special importance. The reliability of supply to essential operations for which stand by supply has to be designed. Electrical installation is designed by building architect with the help of electrical engineer.

In electrical installations safest protection is an active filter in the dedicated lime that follows the sine wave and clamps voltage spikes.

The following factors must be taken into consideration for electrical installation –

(i) Power supply:

Characteristics of the available supply, such as nature of current, number of conductors, voltage and frequency value, maximum allow­able current, protective measures inherent in the supply must be known.

The standard voltage in single phase 2 wire systems must be 220 V. In 3 phase system standard voltage should be 415 V with 240 V between live and neutral.

(ii) Nature of demands:

The number and type of circuits required are de­termined by location of points of power demand, loads expected in the various circuits, daily and yearly variations in demand.

(iii) Emergency supply:

Certain areas will need standby supplies to pre­vent any interruption in power supply to life saving equipments, or other equipments. The electrical installations should take into account the possibility of either an automatic change over or selective connection of standby supply to critical areas.

(iv) Environmental conditions:

The following environmental factors also apply to buildings:

(a) Water: Possibility of free falling drops or sprays.

(b) F6reign solid bodies: Dust etc.

(c) Corrosive polluting substances.

(d) Mechanical stresses: Impact, vibration, etc.

(e) Seismic effects and lightning.

(v) Type of wiring and method of intuition:

It depends upon nature of installation. The major portion of design of, installation relates to this. The cables should not be laid in same trench alongside a water main, sheathed or sheathed wires can be used in low voltage installations. In 3 phase circuits, neutral conductor can be incorporated.

(vi) Protective equipments:

Protection must be provided against the following:

(a) Protection against d.c.

(b) Protection against indirect current

(c) Protection against thermal effects

(d) Protection against over currents

(e) Protection against over voltage

(f) Protection against fault currents.

(vii) Disconnecting devices:

Disconnecting devices provided to permit disconnections of electrical installations or maintenance, testing and fault detection.

(viii) Accessibility:

Adequate passageways shall be allowed to all accesses to switch board for operation and maintenance.