Operating Mode; Earth Connection Resistance Measurement - PCE Instruments CHAUVIN ARNOUX C.A 6421 Mode D'emploi

3.1 EARTH CONNECTION RESISTANCE MEASUREMENT

Two rod-based methods let you measure earth connection resistances with the C.A 6421.
The Tagg-method (said " of the 62% ") is indiscutably the best. It requires an unhindered stretch
of land at least 100 m in length, close to the earth connection to be tested.
The triangular method also provides suitable results, although test results may be vitiated in
the event of overlapping vicinitiy areas.
3.1.1. Measurements using the method " of the 62% "
Switch off the installation and disconnect it from the ground by opening the
earthing rod!
1. Connect terminal E to the earth connection to be tested.
2. Check that the bar 4 was not installed between terminals S and H.
3. Push down the rod H into the earth as deeply as possible, at a distance "a" from the earth
connection (E).
Note: this distance will be proportional to the depth of the earth connection (wider vicinity area).
4. Similarly, push down the rod S by lining it up with the earth connection E and the rod H,
at a distance of about 62% of "a".
5. Connect the test leads between the rods and their respectives terminals.
6. Press the pusbutton 11 till the galvanometer pin stabilizes. Make sure none of the three
indicators is blinking, otherwise check the connections (see § 3.3: FAULT INDICATION)
and repeat the measurement.
earth bar E
earth
point
0 %
Earth resistance measurement using the method of the 62%

3. OPERATING MODE

E S H
S''
52
%
18
S'
S H
62 72 % 100 %
%