10. Earth resistance measurement
The Megger MFT family of test instruments offer a unique solution to the measurement of earth or ground electrode
(rod) supporting 2 and 3 wire measurements:
The MFT1835 and MFT1845+ can use an optional current clamp (MCC1010) to measure electrode (rod) resistance
without disconnection, leaving the installation earthing system intact (Attached Rod Technique, ART). Additionally,
they can drive an optional voltage-inducing clamp (MVC1010) which, in conjunction with the MCC1010, can be used
to make stake-less measurements of the earthing system.
For the principles of Earth resistance testing see “18. Appendix F - Earth resistance testing – Basic principles”
on page 62
10.1 Connection terminals
The terminal references used on the MFT are:
E
H
S
The terminal colours correspond to the Earth test lead set, not the standard test leads shipped with
the MFT1800 series.
MFT1835 and MFT1845+ Connection panel
I
CAT IV
300V
12-15V
1.2A
H E S
V
10.2 Touch voltage limit
Adjust the touch voltage limit to 25 V or 50 V depending on location. “11. Setup options” on page 53.
10.3 Making a measurement - Two pole resistance measurement
1. Connect the instrument as shown below.
I
H
SE
CAT IV
300V
12-15V
1.2A
Electrode under test Potential stake
www.megger.com MFT1800 series
49
Earth resistance measurement
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