Electric Supply System (A.C.)

In present times if power generation system is to be taken into consideration, it should be seen that the 3 phase format with limits including 11 kV and 50 – Hz is taken. It is noteworthy that voltage levels in all these transmission formats are kept within a range of 60 kV to 90 kV at times stepping it up to 132 kV to 400 kV. With the help of these transmission systems, it can be seen that power reaches sub-station and from there it further is distributed in cities or other areas. Also, as per requirement, it can be seen that voltage range can be reduced to a minimal of 11 kV to raised to a maximum of 66 kV.

In case of four phase distribution system, it can be seen that an it has to reach small consumers, therefore, voltage level is stepped up to a maximum of 415 kV.

Small consumers or areas that required less power the general level of flow is 415 kV and in case of very minute section of domestic consumer, it can be seen that they make use of both single as well as four phase level circuit. Therefore, most of these consumers make use of self-installed sub-station that make voltage level at times drop to 415—420 kV as per their convenience.

4 wire distribution system: 3 phase category

Since in India electricity ids supplied to domestic consumers via the state electricity board, therefore, there are 3 specific formats for this supply:

  • The 3 phase AC system with 3 wire format
  • The 2 phase AC system with a 2 wire format
  • Both 3 phase and neutral system with a specific 4 wire format system

Though DC connections are not used on a regular basis however, it can be seen that with this system power range is kept within 220 kV to a maximum of 400 kV.

Certain points have to be remembered:

  • A certain sense of standard measurement is to be kept, and this is essential both for users of electrical gadgets, suppliers of electricity and makers of such gadgets.
  • While connecting electric loads, it can be seen that load should be equal in case of all the 3 phases. If single phasing is considered, it can be seen that balancing has to be done in such a manner that various singular consumers are connected and neutral wire that is present is completely negated from this connection.
  • Those consumers who have requirement of power in large amount is generally satisfied by providing both 3 and 4 phase loading, which have the capacity of balancing each other in case of excess.

The tolerance level of voltages:

If a transmission of current is taking place throughout the day, having sudden drops in terms of voltage level is normal. It is important that while this drop takes place, a minimal range is maintained and for a nominal voltage, prescribed range is within 228 V to 252 V.

The general line that is taken into consideration, in this case, is that for a nominal voltage range making it up to 415 V, the general range is 395 V to 436 V.

Service connections:

In this case, it can be seen that it is via these overhead lines that provide electric to concerned consumers and that line which brings low voltage distribution level up to service are of customers. The power that is brought into premises of consumers is either via overhead lines or underground cables. This is known as service connection, and in these areas, there is a specific service connection that is installed.

Now, this service connection has to be connected to service premises of consumer’s internal wiring, and it is called service mains level. It is further connected to aninput terminal that is placed. In certain cases, an underground service connection can be taken from an overhead distributor, making this whole process a systematic one.

Service mains:

In this connection system, when the supplier’s service line is brought within the domestic consumer’s premises, it can be seen that to get ideal supply connection has to be made up with internal wiring process.

This internal wiring meter is connected to an energy meter that keeps a tab on the total amount of energy that is consumed. It is based on this energy count that at the end of the month, the supplier gets a certain amount from the consumer.

The target process followed is getting the incoming cable connected to anenergy meter, which is further send off to consumer’s primary switch via a cut-out and at the end, it is placed at distribution box to send it over to sub-circuits for further distribution.

Supply of electricity to domestic and commercial premises:

From a pole that is placed at an overhead tower, via a service line, or it can also come in via underground cables that are set. It is to be noted that after energy meter is made live, there is a neutral wire that has to be kept in a fixed position and connected to that link which is supplied via supply mode.

The final supply of electricity comes from meter box that is installed in every house that helps in determining financial amount. In present times, there is usage of small circuit breakers as well as automatic isolators apart from usual fuse grips.

In commercial domains, it is usually the 3 or 4 phase wire line that is used, and 3 phase motors are used for lightening the total amount of load into it.

Wiring systems:

There are multiple wiring systems that are present though not all can match up to installation required at different areas. It is very important that when you choose out a specific wiring system, area of usage (domestic or commercial), voltage levels as well as required atmosphere has to be taken into consideration.

The various classification of this system includes:

  • Distribution format
  • Tree format

Tree format:

In case of tree format, it can be seen that branch circuits are tapped from main areas into a specific arena.  Also, there are a number of joints that make them difficult to locate making installation process a difficult one.

Though as an advantage it is low on cost, however, its disadvantages include, faulty location and scattering of fuses apart from regular effect on voltage drop and poor placement.

Distribution format:

In this format, there are multiple distribution centers from where mains are taken and connected to a single distribution board. Since there are no joints associated in this whole circuit system, so at point, disconnection can take place, and there is no effect on the whole circuit.

As part of the disadvantage section, it is costlier due to presence of multiple wires. The multiple advantages of this format include, the fault location is easier, and it is well protected via a fuse. Also, since fuse can be easily replaced therefore chances of extensions are high with standard voltage maintained at all points.

Domestic installation wiring system:

As part of domestic installations, it is important to note that options as surface contact and concealed contact should be there. The specific categories are:

  • Lead sheathed wiring
  • Conduit wiring
  • Cleat wiring
  • CTS wiring
  • Capping wiring and wooden casing

Lead sheathed wiring:

This implies presence of a conductor that which is covered by covered by a general lead sheath and has well insulated 2 or 3 core that is fixed to a wooden baton via metal clips and therefore forms a good system. In case of breaking of a wire in the midst of the system, a metal made junction box can be introduced, and thereby continuity of this sheath can be maintained. However, these are not used in present times.

Conduit wiring:

In this case, an ideal protection can be found against any external injury or any other fire related risk. There are PVC wires present that make a major part of this system, and it is further used in commercial zones under proper concealing. With such conduit pipes, there is no need for such threading and jointing purpose is made with the help of a specified solution and they are flexible in nature.

The major advantages associated with this format are being risked free in nature, and both return and lead wires can be connected to a singular pipe. Also being shock-proof in nature, earthing that is done is assured with waterproof and easily replaceable facility.

The negative impacts associated with this format is that, for negating consistent voltage drop there is need for a wire bunching system that is both costly as well as require utmost skill.

Cleat wiring

In this case, the insulated conductors that are placed are supported by porcelain coverings and being cost-effective are suitable only for temporary purpose. The wires, in this case,are placed in a 3 groove format.

The major plus points of this format of electrical wiring are that they reduce risk of short circuits and fire accidents at large. Also, being low in cost, they can easily get altered and repaired as per demands.

However, there may be certain issues regarding getting mechanical injuries and requirement of daily cleaning format.

CTS wiring

In this system, tough rubber sheathes of PVC wires are required for covering up of wires and clipped wooden button that is formed is fixed on the ceiling. It is only indoors that this PVC wire can be used since it does not function when placed in a sunlight prone area, as it favors damp climate conditions.

The advantages of this wiring system are that they are not only cheap but also provides a mechanical and short circuit free system. Only joint link clips and general link lips are used in this case, and it has to be protected from any type of strong climatic conditions.

Capping wiring and wooden casing

In this case, there is a rectangular wooden box with grooves that provide insulation to wires especially in the indoor domain. This casing is attached, and PVC is used on a regular basis. However, it should be remembered that the positive and negative wires should have different channels to follow and crossing should be avoided at all costs to ensure proper preventive measures.

The multiple advantages associated with this format include placement of wires in separate grooves and good for installation that is low on voltage rates. Also, they being less costly, it can be easily repaired.

The primary issues associated with this are chances of fire-related damage and skilled worker is required for preparing these casings.

If all these 4 casings are to be compared on a regular basis, certain standards are to be taken into consideration.

  • For mechanical protection: All these casings range from fair to a very good category.
  • For category of personnel required: All these casings rate from semi-skilled workers to well-qualified
  • For category of monetary amount: The amount ranges from minimal amount to a maximum range.
  • For category of dampness: It ranges from requirement of minimal damp conditions to a maximum of sunlight conditions.

Accessories and specification of wiring:

This is associated with wiring procedure that is placed within a particular area.

In case of wiring, solid andmultistr and conductors present. The general insulated pipes that are used are: Volcanized rubber, weather proof wires, flexible wires.

The various types of switches available are: Single to three pole switches and finally to multiposition switch that has a socket outlet and an interlocking switch system.

The multiple categories of sockets range from: One with 5 amperes to a maximum of 15 amperes and on with water tight fitting. There is also presence of an interlocking switch.

The wiring ranges from general type to concealed ones to intermediate and period limiting wiring.

In DC distribution system, electrical energy is spread via 2 or 3 format pipes. There is a singular generating station that goes directly to consumer’s sub-station.

In case of 2 tier DC distribution system, there are two wires, with outgoing wire being of the positive type and incoming wire being of the negative range. The cables are distributed via feeders and help in connecting of bus bars that are further used for serving separate consumers

who have a single distributor to look fort to for ensuring the consistent supply of power. Also what is needed is connecting of motors and electrical appliances in a format that runs in a parallel mode with two wires running simultaneously.

In case of 3 wire distribution system, it can be seen that there are two exit points with a neutral wire placed in the mid-point. There is also consumer apparatus present that is connected to one side neutral point and the other side to the outgoing power point. Finally, to increase the level of efficiency in transmission, it is important that voltage amount of current that is available between two exit points are placed at a greater level in comparison to the terminals that are to be placed at consumer’s end.

Only when all these details are clarified can a student get a complete idea of this subject and solve the associated sums in an ideal manner.



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