Circuit for Operation Either Both Lamps in Series Or Both In Parallel Across Main

Circuit for Operation Either Both Lamps in Series Or Both In Parallel Across Main Points : circuit for operation either both lamps in series or both in parallel across main Such a circuit is most useful practically for having a lamp load to be connected across 230 V supply mains as well as for 400 V mains. Since each lamp is for 230 V mains, so when they are to be operated at 400 V. they are connected in series, and for operation at 230 V they must be in parallel. Such a circuit can be obtained with the help of a 2-terminal two-way switch. When the switch is at top making contact with terminals 1 and 2, the lamps are connected in series as shown in Fig. When the switch is moved down making contact with terminals 3 and 4 the lamps are connected in parallel across 220 V mains.

Such a circuit can also be obtained with the help of either two ordinary 2-way switches and a single-way switch or by a single 2-way switches and single-way switch or by a single 2-way ON and OFF switch and a single-way switch.

Fig. (a) represents the circuit in which the position of 2-way switches is so shown that the lamps become in series while Fig (b) represents the position of 2way switches for the lamps to be connected in parallel across the main;