SCT-013 CT clamp
Also known as: SCT-013-000 · SCT-013-030 · CT clamp · Power & energy
Clip-around current sensing with zero electrical contact: the safest DIY way to see whether the washing machine is running or how hard the workshop circuit is working.
As an Amazon Associate and an affiliate we may earn from qualifying purchases. Prices and availability are set by the retailer.
At a glance
⚑ flag an error| Measures | current |
|---|---|
| Accuracy | Non-invasive AC current; accuracy limited by the ESP's ADC |
| Interface | analog (-030 outputs 1 V; -000 is current-type and needs a burden resistor) |
| Supply | passive |
| Battery-viable | Yes (deep-sleep friendly) |
| ESPHome | Native ESPHome component — ct_clamp |
| Typical price | $3-6 (street, varies) |
Compare all sensor modules in one table →
Which one do I buy?
vs PZEM-004T: the PZEM gives real power and energy for a few dollars more; the clamp wins on absolute simplicity and safety.
Clone check
Low clone risk. Buy from any reputable listing.
Good for
Gotchas to know
- It measures current only — no voltage, so 'power' assumes a fixed 230/120 V and ignores power factor.
- The ESP32 ADC is nonlinear; calibrate against a known load (a kettle) and don't expect utility-grade numbers.
- -000 vs -030 matters: the -000 needs a burden resistor or it produces dangerous open-circuit voltages.
Wiring it up
Analog output: use an ADC1 pin (ADC2 fights with Wi-Fi), expect the ESP32's ADC to be nonlinear at the extremes, and calibrate in software. Any dev board with a spare ADC pin works.