Home Analytics: IoT Energy Meter

Monitoring how much power your air conditioner or computer server is using can save you significant money. The IoT Energy Meter safely clips around a power wire without requiring you to cut or strip dangerous 220V A/C cables.

Safe Measurement (SCT-013)

Cutting an extension cord to wire it through an Arduino is incredibly dangerous. Instead, we measure the electromagnetic field generated by the wire.

1. The SCT-013 Split-Core Current Transformer operates like a clamp. You open it, clamp it around the Live (or Phase) wire of an appliance cord, and snap it shut.
2. As AC current flows through the house wire, it induces a tiny, safe voltage (e.g., 0-1V) inside the sensor clamp.
3. The Arduino reads this tiny voltage via a specialized library (EmonLib.h). The library handles the complex RMS (Root Mean Square) math required to convert the fluctuating sine wave into a usable number: Current = 5.2 Amps.

Cloud Integration (Blynk or Thingspeak)

Knowing the current is 5 Amps right now is good, but graphing it over a month is better.

• You use an ESP8266 or ESP32.
• You multiply the Amps by your local voltage (e.g., 5.2A * 220V = 1144 Watts).
• The ESP calculates Kilowatt-Hours (kWh) and pushes the data to a free cloud dashboard like Blynk or ThingSpeak via HTTP POST.
• You can now look at your phone app to see exactly how much money your TV costs you while resting in standby mode!

Hardware Needed

• ESP8266 NodeMCU or ESP32: For Wi-Fi connectivity.
• SCT-013 (e.g., 100A/50mA version) Clamp Sensor.
• (Note: Ensure you clamp only the Live wire. Clamping both Live and Neutral simultaneously cancels the magnetic field, resulting in a reading of zero Amps).