In domestic electric circuits the wiring with 15 A current rating is for the electric devices which have

In domestic electric circuits, power is supplied through two distinct current-carrying circuits to ensure safety and efficiency:

1. A circuit with a 15 A current rating is specifically designed for electrical appliances that have higher power ratings (such as geysers, air conditioners, and electric ovens) because they draw a larger current from the mains.
2. A circuit with a 5 A current rating is used for appliances with lower power ratings (such as bulbs, tube lights, and fans) which draw very little current.

Why other options are incorrect:

• Option (b) is incorrect because appliances with lower power ratings like fans only require a 5 A circuit.
• Options (c) and (d) are incorrect because the current rating of a circuit is determined by the power consumption (current drawn) of the device, not by whether its body is metallic or non-metallic. (While metallic bodies require an earth wire for safety, this is independent of the 15 A rating itself).