Yokogawa 700924 Overview
Oscilloscope input amplifiers are normally single-ended. They do not provide accurate measurements when used in combination with a 10:1 passive probe for measuring the gate-to-source voltage of a switching power supply, or potential difference with a common mode voltage in elements such as Insulated Gate Bipolar Transistors (IGBTs).
Furthermore, there is a risk that current will enter through the oscilloscope ground line and damage the oscilloscope.