User`s guide

Measurement Tutorial 3
34450A User’s Guide 79
Figure 3-2 Noise caused by ground loops
The best way to eliminate ground loops is to isolate the
multimeter from earth by not grounding the input terminals.
If the multimeter must be earth- referenced, connect it and
the device-under-test to the same common ground point.
Also connect the multimeter and the device- under- test to
the same electrical outlet whenever possible.
Ideal
Meter
R
L
R
L
HI
LO
V
ground
V
test
R
i
>10GΩ
R
L
=LeadResistance
R
i
= Multimeter Isolation Resistance
V
ground
= Voltage Drop on Ground Bus