Restart timer for a device
There are commercial timers that will do what you want, but they are quite expensive, even in the US; for example this one -- TORK Electronic Timer # E101B 120-277V SPST --is $74 from Amazon.  (Intermatic makes a less expensive appliance timer, but since the on/off periods are set mechanically, I don't think you can get a small enough off period).

Circuit wise, it is not too difficulty to make your own using a 555 chip configured as an astable multivibrator.



Use Right-Click View Image to see a larger version of this schematic.

The values for R1 and R2 and C1 are selected such that the on time is 4 hours (240 minutes), and the off time is five seconds.  If the latter is too short, you can calculate new values here (scroll down to the ASTABLE OSCILLATOR CALCULATOR).  The times are not going to be that accurate though, due to the tolerance of the 4700 µF capacitor.  So you may have to fine-tune the circuit after building.

The hardest to find part will be the relay; I found one at Digi-Key that has a 12v coil, and is rated at 7.5A inductive at 250 VAC.  I doubt if you are going to try getting that exact one since you are in India, but you will need to look for one that meet your switching requirements (you didn't mention them, so I just guessed).

BE VERY CAREFUL wiring the section for 240 VAC, this voltage is lethal.  I would build the circuit, and then test it (without being plugged into the 240 VAC mains) by using a voltmeter across each of the contacts.