Measurement Tutorial
3
Keysight U2741A User’s Guide
51
Figure 3-2
Ground loop induced error
The best way to eliminate ground loops is to isolate the digital multimeter from
earth by not grounding the input terminals. If the digital multimeter must be
earth-referenced, connect it and the device under test to the same common
ground point. Also connect the digital multimeter and device under test to the
same electrical outlet whenever possible.
R
L
= Lead Resistance
R
i
= digital multimeter Isolation
V
ground
= Voltage Drop or Ground Bus
R
L
R
i
> 10 G
Ω
V
ground
R
L
V
test
LO
HI
Meter
Ideal
Resistance