Arduino - Cheap/Poor Man's CT Sensor

There are several references on how to do this such as;

• CT sensors - Interfacing with an Arduino
• How to build an Arduino energy monitor - measuring mains current only.

For my case, I would like to try it first before start buying a CT sensor.
So I come out with below idea, using toroid inductor/coil for testing.

Live wire 240VAC going through the toroid.
Please take precautionary steps with this.

Arduino and sensor board setup

#include "EmonLib.h"                   // Include Emon Library
EnergyMonitor emon1;                   // Create an instance

void setup()
{  
    Serial.begin(9600);
    emon1.current(1, 500);             // Current: input pin, calibration.
}

void loop()
{
    double Irms = emon1.calcIrms(2000);  // Calculate Irms only
    Serial.println(Irms);          // Irms
}

Arduino sketch - quick copy/paste code

Hook it up and testing. It will not be accurate, just to get an idea on how it works.