What Is Service Mains, Types, Advantages, Disadvantages

July 24, 2020December 14, 2022 CS Electrical And Electronics

Hello guys, welcome back to our blog. In this article, we will discuss what is service mains, their types, advantages, and disadvantages of service mains.

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What is Service Mains

Meaning Of Service Mains

The overhead line or U.G cable connecting the supplier’s distribution line to the consumer’s premises is called service mains or service connection or service line. The service line terminates at the point where the supply conductor enters the consumer meter.

See guys the purpose of a low-tension line is to transmit electricity from a distribution transformer to every street near the consumer, now how is the electricity from a low-tension line brought to the consumer’s house? This work is done by SM, SM is nothing but the conductor used to transmit electricity from low-tension lines to the consumer meter board.

As you can see in the above image SM will look like that, it consists of PVC insulation and the inside conductor is of aluminum before that copper conductor was used but the cost was a little expensive so copper is now replaced by aluminum.

Types Of Service Mains

There are two types of Service Mains :

To transmit electricity from low tension lines to the consumer meter board there are two ways to transmit electricity: one is overhead SM and another method is underground SM.

01. Overhead Service Mains

Overhead Service connection means conductors are drawn or taken above the ground level as shown in the above figure. Overhead service mains are the most common type in India. In overhead service mains, there are some materials used like insulators, wire, etc.

Now I will tell you what the materials used in overhead service mains; the materials used in overhead SM are break insulators, real insulators, messenger wires, service wires, conduit pipes, GI pipes, etc. In the next article, I will discuss in brief all these materials.

Advantages Of Overhead System

(a). Extension of service line capacity is easy – Yes if you want to convert from a single-phase supply of your house to a three-phase supply then you can easily do it in overhead SM and it is very difficult in underground SM.
(b). Fault location and rectification are easy – If any fault occurs in overhead SM then you can easily find the fault and do the repair but in the case of underground SM fault location is very difficult compared to overhead SM.
(c). Easy to Erection – Erection of overhead SM is easy compared to the underground SM, in the case of underground service many things should be done like digging for pipes, and materials cost is also very high in underground SM.
(d). It is Cheap – Materials required for overhead SM are of less cost compared to underground service mains.

Disadvantages Of Overhead System

Disadvantages of Overhead connection with underground connection are :

(a). Ugly appearance – It will not be good in appearance as the wire are visible, suppose your house is new then the wire of service disturbs your house’s appearance or view.
(b). Overhead space is affected – As the wires are taken from above the house roof if you suppose your child goes and touches the wire he may get shocked, so it is not safe.
(c). Affected by weather such as sun heat and rain lightning – Overhead SMs are affected by climatic conditions like rain, sun, etc. In some years the insulation of SMs will get damaged due to the sun or rain.
(d). Faults due to falling of trees, monkeys, birds, and reptiles.

02. Underground Service Mains

Underground Service Connection means conductors are drawn or taken below the ground level as shown in the above figure. It is very difficult to install underground SM compared to overhead service mains. The materials used in underground service mains are GI pipes, underground cables, potheads, GI bands, etc material details will discuss in the next article.

Advantages Of Underground Service Mains

The advantages of underground connection compared with overhead connection are ;

01. Long-life – Underground SMs are life-long as it is a permanent and it is one-time investments.
02. Not affected by weather such as sun, light, rain, lightning, etc – So that this system can be used for life long.
03. Safety to the public – As it is installed below the ground it is easy for the public as compared to overhead SM it is not safe.
04. It is used in metro and corporate cities where overhead connection construction is very difficult.
05. Good Appearance – It is good for our house’s appearance as compared to underground service mains.

Disadvantages Of The Underground System

Disadvantages of underground connection compared with overhead connection are ;

01. Fault location and rectification are difficult – If any faults occur in underground service mains, it is difficult to identify the fault but in the case of overhead SMs it is easy to identify the fault.
02. Skilled laborers are required – Yes skilled laborers are required in the case of underground SMs because the erection of underground service is complicated compared to overhead service mains.
03. It is costly – The cost of underground SM materials is more compared to materials of overhead SMs.
04. It requires more time for erection and Dismantling.

Conclusion: Which is the best overhead SMs or underground service mains? According to my, if you spend more money, then go for the underground SMs and if you can’t spend more money then go for overhead Sms. Underground SM is best and it has many advantages.

Code Of Practice

1) Tapping

The service line should be tapped from the over headline-only at the point of Support.

2) Earth Leakage Circuit Breaker

Earth Leakage Circuit breaker (ELCB) is to be used when the load exceeds 5 KVA.

3) Lead-in-pipes are used for Service connection.

4) Three-Phase

When the total load exceeds 10 KVA, the three-phase connection is used.

5) Ground Clearance

When the service line is erected across the road or along the street should not be less than 5.7m above the ground level.

6) Meter Board

The meter board should always be placed at the entrance at a height of 1.5 m from ground level.