Counting pulses on electricity meters

I want to count pulses on electricity meter and from that to estimate power consumption of a house.
I tried to use the arduino sketch Interrupt method given on the page Reading pulses from meters with pulse outputs of openenergy monitor website. But the code is not working properly or may be I didn’t understand the output. If there is only one load continuously running then I should get constant power consumption but the power values I am getting from sketch are continuously increasing. What does elapsedkWh means?

From what you write, I think you do not understand the difference between power and energy.

If you have constant power consumption, then your consumption of energy will increase at a constant rate. It is because energy is the total power accumulated over time. Or if you prefer, power is the rate at which you use energy.

Look at the units: power is measured in Watts (or multiples or sub-multiples - kW or mW) and energy in Watt.hours (that is Watts times hours), or Joules (1 J = 1 W.s - Watt.second). So if you use 1 kW of power for 1 hour, you have used 1 kWh of energy, 3600,000 J (3.6 MJ).

Your electricity supplier supplies you with power, but you pay for the energy that you use.