Owon DSO-2072H Quick Start Manual page 4

To prevent electric shock or fire, use a suitable power adapter. Refer to section
"General Technical Specifications" for further information relating to the power
supply.
Warning:
The two channels of the oscilloscope are non-isolated channels. Note that the
channel should use a common reference when measuring, and the ground
wires of the two probes cannot be connected to two non-isolated places with
different DC electrical levels, otherwise it may cause a short circuit due to the
ground wire connection of the oscilloscope probe.
Warning:
Note that the channel should use a common reference when measuring,
otherwise it may cause a short circuit due to the ground wire connection of the
oscilloscope probe.
Schematic diagram of the internal ground wire connection of the oscilloscope:
Signal Input
Ground Clip
When the oscilloscope is AC powered by adapter or connected with AC
powered computer through the port, it is not allowed to measure the primary
power supply of power grid.
Warning:
If the input port of the oscilloscope is connected to a voltage with a peak value
higher than 42V (30vrms) or a circuit with a peak value of more than 4800 VA,
the following measures shall be taken to avoid electric shock or fire:
Oscilloscope
Probe AC Adapter
USB Cable
2
Electrical Outlet