When the probe is connected to the circuit under test, the grounding end of the probe must be connected to the ground wire of the circuit under test.Otherwise, in the suspended state, the potential difference between oscilloscope and other equipment or ground may lead to electric shock or damage to oscilloscope, probe or other equipment.
When measuring pulse and high frequency signals with short setup time, try to put the grounding wire of probe close to the position of measured point.Excessively long grounding wires may cause distortion of waveform such as ringing or overshooting.
A special earthing attachment for the probe is recommended to avoid the influence of the grounding wire on the testing of high frequency signals.
To avoid measurement errors, be sure to check and calibrate the probe before measurement.
For high-voltage test, a special high-voltage probe should be used. After the positive and negative electrodes are clearly divided, the measurement can only be started after the connection is confirmed to be correct.
When both test points are not at ground potential, "floating" measurements, also known as differential measurements, are made using a professional differential probe.