"so as to i can feed it to ADC0804 or ADC0808 and than buy 89c51 i can do the calculation ie P=IxV and E=PxT.."

What happens to power factor ? Unless all loads in the house are PURE resistors ... which is very unlikely.

I am not discouraging you, but measuring AC power consumption is not that simple as it sounds.

Time to reach for that book on Basic Electricals in the attic, dust it and READ it.

And since you asked : Analog Devices has special chips exactly for this job. Check out thier site. Maybe there are other manufacturers also.

Raghu