Term Use in Electrical Distribution System

Term Use in Electrical Distribution System Points : term use in electrical distribution system Points The termination of fixed wiring feeding a lighting fitting, socket outlet or any other current consuming appliance is called a Point. Main Cable Main Cables are classed as those leading tip to combination switchfuse hoards, or in the case of smaller installations, up to the main distribution fuse board. Sub-Main Cable Cables feeding distribution fuse boards which supply two or more final Sub-circuits, are classed as sub-main cables. Final Sub-Circuit A final sub-circuit is the last circuit in the installation leading to a load. It is connected to any one way of a distribution fuse board or switchfuse feeding one or more points, without a distribution fuse board in between. Thus a final sub-circuit might consist of a pair of 3/.029 cables feeding a few lights, or a heavy 3 core cable feeding a large motor direct from a circuit breaker on the main switchboard. Final sub-circuits can be divided into two groups-those with a rated capacity of under 15 amp, and. those with a rated capacity of 15 amp and over. Any number of appliances can be connected to a final sub-circuit so long as the total of their rated full load currents do not exceed 15 amp.’ Only one appliance however, may be fed by a final sub-circuit if its rated full load current exceeds 15 amp. Voltages Extra low:- not over 50 volts a.c., with a maximum voltage to earth of 30 volts a.c. or 50 volts d.c.
Low: Over:- 50 volts and up to and including 250 volts.
Medium:- Over 250 volts and up to and including 650 volts.
High:- Over 650 volts.