Do these readings for my CT sensor look correct?

Other Hardware Sensors
1

I followed the tutorial here:
http://www.mindkits.co.nz/mindkits-news-and-blog/arduino-energy-monitor

I setup up my circuit for use with 5V (33 ohm burden resistor). The CT sensor I am using is the SCT-013-000 (the 100 amp model).

Below is the basic sketch I am using, I am trying to monitor stuff on a 120 VAC line.

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

void setup()
{  
  Serial.begin(9600);
  
  emon1.current(1, 111.1);             // Current: input pin, calibration.
}

void loop()
{
  double Irms = emon1.calcIrms(1480);  // Calculate Irms only
  
  Serial.print(" Apparent Power: ");
  Serial.print(Irms*120.0);	       // Apparent power
  Serial.print(" IRMS: ");
  Serial.println(Irms);	
         
}

With nothing encapsulated by the CT, or when there is no load I get readings like this:

Apparent Power: 27.19 IRMS: 0.23
 Apparent Power: 27.16 IRMS: 0.23
 Apparent Power: 27.46 IRMS: 0.23
 Apparent Power: 27.15 IRMS: 0.23
 Apparent Power: 27.47 IRMS: 0.23
 Apparent Power: 27.39 IRMS: 0.23
 Apparent Power: 27.32 IRMS: 0.23
 Apparent Power: 27.27 IRMS: 0.23
 Apparent Power: 27.35 IRMS: 0.23

Why do I get readings like this one its not monitoring a load?

These are readings I get from a lamp using a 60 WATT light bulb

Apparent Power: 137.31 IRMS: 1.14
 Apparent Power: 101.34 IRMS: 0.84
 Apparent Power: 100.75 IRMS: 0.84
 Apparent Power: 101.18 IRMS: 0.84
 Apparent Power: 102.22 IRMS: 0.85
 Apparent Power: 102.91 IRMS: 0.86
 Apparent Power: 101.24 IRMS: 0.84
 Apparent Power: 101.24 IRMS: 0.84
 Apparent Power: 101.18 IRMS: 0.84
 Apparent Power: 101.12 IRMS: 0.84

How can I interpret the above data? I am new to this.

2

You will always have noise in ADC measurements, as well as noise induced in your sensor and wiring from the environment. It is encouraging that you appear to see a signal with a 60 watt light bulb, which suggests that everything is working. But that is a very small load!

So now, you need to calibrate your CT by making measurements with a number of different loads, covering as much of the 100 amp range as possible. For example use a 150 watt light bulb, and some space heaters at 500, 1000 and 1500 watt settings. You won't be able to go much higher in current with typical household appliances.

When that is done you will have a good idea about how to calibrate your measurements, including how much noise to subtract from the readings. I've attached an example from one of my projects, using a 60 amp CT from CoilCraft.

CS60.png