A study room is to be wired so that it contains one 40 W tube-light controlled by…
MATHEMATICS · Subjective · ISC · Physics · Current Electricity · Electrical energy and power
Problem
A study room is to be wired so that it contains one 40 W tube-light controlled by switch S₁, one 75 W ceiling fan controlled by switch S₂, and one 3-pin socket outlet rated 6 A. The supply available is 220 V AC through a live (L), neutral (N), and earth (E) conductor.
(i) Draw a neat schematic wiring diagram showing how the three appliances, their individual switches, an MCB (or fuse) and the earth connection can be arranged so that each appliance works independently.
(ii) Explain briefly, with reference to your diagram, why switching OFF any one appliance does not affect the operation of the others.
(iii) If only the tube-light is switched ON, calculate the current taken from the mains.
(iv) When the tube-light, fan and a 500 W device plugged into the socket operate together, calculate the total current drawn. Show that this current does not exceed the 6 A rating of the socket outlet.
(v) List any two safety precautions incorporated in your wiring diagram.