Here is what I made a last year.
PIC 16F876
2x16 LCD
MAX 232
TL084
and 2 old monitor flyback transformer.
Since the voltage is known and constant, you only need to measure the current and time.
I made a current transformer from the Flyback ferrite core.
This ferrite core goes around the main AC line in my fuse box.
It has 100 turn, for 1-100 ratio.
1 amp= 1mv, 102.4 amp= 102.4mv
In my hose there is 2 line come in, so many of the appliance and light feed from different line, I made 2 of this.
Then feed in to a full wave AC/DC convert made of 2 of the four OP-AMP in the 084.
Scale it up to 0-1.024V = 0 to 102.4Amp, my reference voltage is 1.024V to make the math easier.
Than use whatever language you more comfortable to make your code.
In my case BASIC !
I made the projection for current"1sec", 1hr, 1day, and from last reset.
The truth is, I was try to advance it so it will have 64k I2C memory and RS232 link to PC, on the end I have so many time removed from the fuse box on the last attempt the ferrite core bracket touched the unfused terminal of the main line.
As the result I seen a fire work in my basement, and I promised my wife I'll never touch it again !!
Good luck
I hope is helped !
STEVE