Types Method of Installation of Service Lines

Types Method of Installation of Service Lines Points : Types Method of Installation of Service Lines, Overhead service lines, Underground cable service line, For High Roof Building, For Low Roof or Single Storied Building, Weather Proof Cable Method, Use of Junction or Joint Box, Underground Cable Service connections As already mentioned service lines are of two types:
1. Overhead service lines.
2 Underground cable service lines. 1. Overhead Service Lines There are various methods of installation of overhead service lines and their use depends upon the conditions prevailing. The various methods used for installation of overhead lines are: (i) For High Roof Building The wire may be connected to the gable provided that the building has the necessary height and there is no gable window from which the incoming conductor can be reached. In such cases a service bracket (mild steel angle iron piece) is embedded into a wall at a suitable height. The pin type or shackle type insulators are fitted to this wall bracket. The number of insulators to insulators to be fitted depends upon the number of incoming wires (two in case of general service connection and four in case of power service connection). As a rule the vertical distance between the insulators should be 35 cm and the lateral distance 30 cm. The phase and neutral wires are taken from existing service pole and connected to the insulators fitted on the service bracket. The earth wire is connected to angle iron with the help of eye bolt. Now a weather proof or PVC cable is connected to angle iron. Now a weather proof or PVC cable is connected to the conductors (overhead service line) solidly or by means of connectors and may be carried either on wooden batten or inside a GI pipe or conduit of suitable size up to the service board. The G.I. pipe, if used, is bent at the upper end with opening face downward in order to prevent the entry of rain water into the pipe.

Although a house may be high enough for the connection to be made at the gable, it may have windows in the gable from which the gable from wall and thus the house connection at the gable may be reached. In this case, a bracket -pole may be used for lead in arrangement. (ii) For Low Roof or Single Storied Building If a building is of very low height service bracket cannot be directly fixed to the wall, if fixed the power conductors may not have distance from ground as mentioned in IER. In such cases use of roof pole or GI pipe connection is made, In case of roof pole connection, roof pole consists of a strong steel tube (60 mm, 80 mm or 90 mm in diameter) provided with lateral arms on which the insulators are mounted. The height of the roof pole should not exceed 3 meters otherwise the tensile stress involved will become too high. To keep tensile stress low, the roof pole is braced by a steel rope as is done in the case of the stayed pole. If possible the roof pole should be fastened to the main truss of the roof construction. In case of 01 pipe connection 01 pipe is raised above the roof to a suitable height. The GI pipe is suitably clamped to the wall at its lower end and is bent back and provided with a stay at its upper end. The service cable is carried to service board through GI pipe and heavy gauge conduit. (iii) Weather Proof Cable Method In this method an 8 SWG Gi wire is stretched from the service pole to eye screw bolt fixed into a wall at a suitable height (in case of a double strayed building) or to a GI pipe raised ‘above the roof (in case of a single strayed building). The weather proof or PVC cable is then brought to the building by clipping it to the. GI wire stretched between service pole and building and the carried to service board as usual i.e., on wooden batten or in a GI pipe or In a H.G. conduit. (iv) Use of Junction or Joint Box For taking service connection from one house to another house use of junction or joint box is made. In this system the connections from existing pole are taken to the, junction box where the joints to cables for bifurcating the connections are made, as shown. 3. Underground Cable Service connections Use of underground cable is usually made for service connection when the power to be supplied to the consumer is large (say above 25 kw). For installation of underground cable service connection a cable box of suitable size is fitted to the service pole by means of M.S. channel of size 16mm x 250mm and bolts and nuts. The cable is tarried froth the cable box fitted on pole to another cable box fitted on service board; first along the pole to the ground, then in the trench and lastly vertically along the wall to the second cable box. The trench starts from the pole and terminates vertically below the service board. Use of 01 pipe of suitable size is made up to 2 meters from the ground for enclosing the cable in order to save it from mechanical damage at both place i.e., along the pole and below the service board. The cable is held to the pole by means of clamps.