The tester will measure the sum of the earth resistances of both
the electrode under test and the EXCP, which, in the above assumptions,
will practically coincide with the resistance-to-ground of the
electrode under test. Alternatively, the low-voltage neutral of a neighboring
utility substation, or even of a dwelling unit, can be used as a
simultaneous current and potential electrode. In this case, the neutral
must be checked to assure its de-energization.