Download Fluke 123/124

Tips and Troubleshooting
Using Proper Grounding
3
Using Proper Grounding
Incorrect grounding can cause various problems. This
Section gives you guidelines for proper grounding.
Use the short ground lead(s) when measuring DC or
AC signals on input A and input B. (See Figure 3-2.)
Warning
To avoid electrical shock or fire, use only one
COM (common) connection , or ensure that
are at the same
all connections to COM
potential.
Figure 3-2. Grounding with Short Ground Lead
Use the unshielded black ground lead to COM
(common) for Ohm (Ω), Continuity, Diode, and
Capacitance measurements. (See Figure 3-3.)
Using the unshielded ground lead is also possible for
single or dual input measurements for waveforms with
a frequency up to 1 MHz. This may add some hum or
noise to the waveform display due to the unshielded
ground lead.
Figure 3-3. Grounding with Unshielded Ground Lead
59