Typical sources of test errors

If you see excessive errors during accuracy testing, examine your test setup and test procedures to eliminate typical sources of measurement errors.

Typical sources of accuracy verification testing errors include:

Loose connections of voltage or current circuits, often caused by worn-out contacts or terminals. Inspect terminals of test equipment, cables, test harness and the meter under test.
Meter ambient temperature is significantly different than 23 °C (73 °F).
Floating (ungrounded) neutral voltage terminal in any configuration with unbalanced phase voltages.
Inadequate meter control power, resulting in the meter resetting during the test procedure.
Ambient light interference or sensitivity issues with the optical sensor.
Unstable power source causing energy pulsing fluctuations.
Incorrect test setup: not all phases connected to the reference device or the energy standard. All phases connected to the meter under test should also be connected to the reference meter/standard.
Moisture (condensing humidity), debris or pollution present in the meter under test.