Negative power displayed on a Clamp-on Power Logger

Negative power displayed on a Clamp-on Power Logger

Question

I measured the power trend using a Clamp-on Power Logger, but the power value is negative. Why does this happen?

Answer

Unless the load is generating power, the value shall be positive (consumption).  Please check to see  if the clamp-on sensor is positioned in the reverse direction, by verifying that the arrow marking on the sensor head is pointing in the direction from source to load.