In domestic electrical wiring,what is the red-colored insulated wire used for?

What precaution should be taken to avoid the overloading of domestic electric circuits?

In a household electric circuit,different appliances are connected in parallel to one another. Give two reasons for this. An electrician puts a fuse of rating $5 \, A$ in that part of a domestic electrical circuit in which an electrical heater of rating $1.5 \, kW, 220 \, V$ is operating. What is likely to happen in this case and why? What change,if any,needs to be made?

Name the type of current:
$(a)$ used in household supply,
$(b)$ given by a cell.

$(a)$ State the function of a fuse in an electric circuit. How is it connected in the domestic circuit?
$(b)$ An electric fuse of rating $3 \, A$ is connected in a circuit in which an electric iron of power $1.5 \, kW$ is connected,which operates at $220 \, V$. What would happen? Explain.

What is the function of an earth wire? Why is it necessary to earth metallic appliances?