Humboldt H-4385 Resistivity Meter - Manual (Page 9)

As indicated in Figure 5, in this configuration, jumper wires are connected between
terminals C1 and P1 and between terminals C2 and P2. In addition, test leads connect
one of the electrodes to terminal C1 and the other electrode to terminal C2.
Another configuration option, which is recommended for use when measuring small
resistances, is to connect the potential terminals (P1 and P2) directly to the electrodes
with separate test leads, thus eliminating the jumper wires. Such a configuration
eliminates any voltage drop in the test leads due to current flow in the leads which would
appear in series with the voltage drop occurring between the electrodes in the case of
the configuration shown in Figure 5.
The resistance reading determined by the H-4385 will be a direct measurement of
resistance comprising 2 components; the resistance-to-earth contribution of each
electrode (which itself comprises 3 components (see the “3-Electrode Application”
section above) and the earth’s resistance between the two electrodes.
Maintenance & Calibration
Other than changing the batteries, the H-4385 requires no maintenance.
When the “Low Battery” indicator lights up (and remains ON) during a balancing
procedure, the batteries should be replaced. The procedure to change the 8
C-size alkaline batteries in the unit is as follows:
1) Remove the 4 screws on the front panel and lift the panel out of the plastic
case.
2) Turn the panel upside down and place on a clean (and dry) surface
3) Undo the four retaining clips and remove the two sets of 4 old batteries from
their holder tubes.
Figure 5