What Line to Test on INA219BIDCNR to Sense Current

We’ve had customers ask whether the hot or neutral line is recommended to sense current for INA219BIDCNR when designing for an AC mains application. This article will answer which line to use and why.

As long as the common-mode voltage (Vcm) rating of the INA219 is not violated, the device will not be damaged.

It is not recommended to connect INA219BIDCNR to the hot line at all. This only works if the device is supplied with a floating 5V source that is derived from the AC voltage itself. For example, if you created an AC to DC voltage rectifier that generates a 5V source that floats with 120VAC, then the INA219 would not break, however, the digital communication lines would still be high-voltage to Earth ground and would require level shifting.

You could connect the INA219 to the neutral line since it is grounded. You should still take precautions to ensure there are no ground loops between neutral and system ground.

Information courtesy of Texas Instrument’s Forum.