Page 929 - Basic Electrical Engineering

Figure 13.10 Three-phase four-wire distribution system

13.9.2 Service Mains

In the main distribution board installed in the premises of the consumer, an

energy meter is connected so as to measure the amount of electricity
consumed by the customer. Thus, the incoming service cable is connected to

the energy meter at the distribution board. A cutout, i.e., a fuse wire is
connected in the line which will blow off in case the consumer draws more

current than the current for which he has been supplied with. In the cutout of
proper rating is not provided, the meter will get burnt in case of heavy loads
(more than the rated load) drawn by the consumer. For example, if the

consumer install more air-conditioners in his house than permitted, the meter
may get burnt. The cutout can only be replaced by the electricity supply

authority. The consumer must not tamper with the cutout. The supplier may
disconnect supply by removing the cutout in case the energy bill is not paid

by the consumer.

13.9.3 Distribution Board for Single-phase Installation

The service mains is connected to the input terminals of the single-phase

energy meter at the distribution board as shown in Fig. 13.11. Before the
energy meter is placed the electricity supply authority’s cut-out. The