ESP32 with SCT-013-020 connecting to WiFi error

I am trying to use ESP32 and current sensor SCT-013-020 to post Current data (Irms) to ThingSpeak.

To problem is the following:
When i run the sample program for reading Current data it works fine:


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

#include <WiFi.h>
const char* ssid = "********";   // your network SSID (name) 
const char* password = "**********";   // your network password

void setup()
{  
  Serial.begin(9600);
  
  emon1.current(34, 9);             // Current: input pin=34, calibration.

}

void loop()
{
  double Irms = emon1.calcIrms(1480);  // Calculate Irms only
  
  Serial.print("Power= ");
  Serial.print(Irms*230.0);	       // Apparent power
  Serial.print(" ");
  Serial.print("Irms= ");
  Serial.println(Irms);		       // Irms= Root mean square current
}

But, when i connect to my wifi network to be able to send data to ThingSpeak the sensor gives me wrong data !!!

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

#include <WiFi.h>
const char* ssid = "*******";   // your network SSID (name) 
const char* password = "*******";   // your network password

void setup()
{  
  Serial.begin(9600);
  
  emon1.current(34, 9);             // Current: input pin=34, calibration.

  WiFi.mode(WIFI_STA);   
  WiFi.begin(ssid, password);
  Serial.println("");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

void loop()
{
  double Irms = emon1.calcIrms(1480);  // Calculate Irms only
  Serial.print("Irms= ");
  Serial.println(Irms);		       // Irms= Root mean square current
}

Without connecting to WiFi and when the test device is OFF i get 0.2 Ampere (good value)
When i connect to WiFi i get 5 Ampere although the test device is OFF !!!

What is wrong with that ?
Thank you in advance for your time.

Are you using the nano esp32 or any other esp32 board?

1 Like

Please expand - how do you determine that?