1.0 Introduction
Electricity gives rise to electrical and electronics installation works. Electrical installation in buildings, factories, villages, towns etc. comprises various types of electrical materials, apparatus and equipment interconnected with cables and conductors in fixed position ready for use. An electrical installation put in place is mainly for the distribution and utilization of electrical energy.
Given the importance of electricity and its usefulness to mankind, regulations and procedures exist to guarantee continuous supply and safety of users of electrical installation. Compliance with regulation and procedures during electrical installation work ensures that the premises so connected as well as users of electricity are protected from electrical accident, shock, fire outbreak and other problems which may result from bad electrical installation works. To achieve these, proper design of the installation must be done which must also conform to the regulations and procedures for electrical installation.
Ikenegbu Layout in Owerri Municipal of Imo State being part of the state capital, Owerri forms residence for the state dignitaries, politicians and civil servants. For these, commercial activities like fast food houses, business plazas, banks etc. are attracted to this area.
The choice of this site as a case study is based on the fact that it has the features of a typical town.
1.1 Standard Voltages and Frequency
The standard ac system voltages as defined in the Electricity Act Supply Regulation 3(2) shall be 230 volts between phase and neutral conductors and 400, 3300, 6600, 11000, 33000, 66000, 132000, 330000 and 750000 volts between any two phase conductors of a three phase system. Presently, the highest standard system voltage in Nigeria is 330000 volts. Functionally, the ranges of the more commonly used voltages are as classified below:
- Extra low Voltage: Voltages below 100 volts.
- Low Voltages: Voltages exceeding 100 volts but not exceeding 250 volts.
- Medium Voltages: Voltages exceeding 1000 volts but not exceeding 3000 volts.
- Extra High Voltages: Voltages exceeding 3000 volts.
In any line circuit at the consumers premises, an electric current will flow from one point to another once there is a potential difference between any two points. The potential difference at the consumer's terminal measured in volts is usually referred to as the supply voltage. The ac voltage normally passes through a complete series of positive and negative circles a number of times per second. This number is usually known as the frequency measured in Hertz (Hz) where a hertz is equal to one cycle per second, the frequency of ac system shall be 50Hz. Due to voltage drop in the distribution system, it is definitely impossible for the supply authority to maintain the same constant voltage at all their consumer's terminals.
However, the supply authority voltage and frequency are not allowed to vary for more than 6% and 1% respectively above or below the declared voltage and frequency. The national agreed low and medium ac and dc voltages are:
- Alternating Current — 240 volts and 415 volts, 3-phase, 4-wire at 50Hz.
- Direct Current — 230 and 460 volts.
Generally, the type of supply to be provided for any area or consumer premises or load in a given area depends on a number of factors. The factors include: distance involved, the available supply system, area spread, the capacity load, and the type of load etc.
This material contains electrical diagrams, circuits, illustrations and more (Very detailed).
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