Question

an electric geyser is rated as 1000 w, 220 v marked on it. What should be the required minimum rating of the fuse wire in amperes approximately

Answer 1

Given, 
Safe power limit = 1kW
Potential difference = 220V
(which is the normal voltage received in houses)
So from the formula
P= VI
We can calculate the safe current
1000 = 220 * I
⇒I= 1000/220 
     =4.54A 
     = 4.6A
We know fuse wire should melt and break the circuit if the current passing through  an appliance passes its safe limit.Hence the fuse wire should be of 4.6A

Answer 2

Answer:

Minimum rating of fuse wire is 5 Ampere as after calculation it gives 4.6 A . So approximately it will be 5 A