Megger DET4 Specifications
Earth/Ground Resistance & Soil Resistivity Testers
DET4 Series
4-Terminal Earth/Ground Resistance
and Soil Resistivity Testers
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2, 3 and 4 point testing
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Stakeless (clamp-on) testing capability
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ART (Attached Rod Technique) capability
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Multiple, user selectable test frequencies
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Resistance measurement range to
200,000 Ω
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IP54 rated
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Warning indicators prevent test failure
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Simple one button operation
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Included leads, stakes, calibration
certificate and rugged carry case
DET4 Series
DESCRIPTION
Megger’s popular 4-terminal ground testing instrument
family includes four basic models with different kit variants
for each that include select accessories for greater testing
flexibility. The four basic units are:
Model Description
DET4TD2 Dry-cell battery powered basic 4-terminal
tester
DET4TR2 Rechargeable battery powered basic
4-terminal tester
DET4TC2 Dry-cell battery powered 4-terminal tester
with selectable test frequencies, greater
measurement sensitivity and attached rod
technique and stakeless measurement
capability
DET4TCR2 Rechargeable battery powered 4-terminal
tester with selectable test frequencies,
greater measurement sensitivity and
attached rod technique and stakeless
measurement capability
The top-end models (DET4TC2 and DET4TCR2) include
a current measuring function for ART (Attached Rod
Technique) testing capabilities. With this added function,
on-site grounds can be tested separately without having to
remove the utility connection (as explained further in this
document). They also provide stakeless testing capability.
This method allows the operator to use the instrument
like a clamp-on ground tester in applications where that
method is viable, while also being able to operate as a fall
of potential tester if required.
The basic kit includes the test leads, stakes, batteries and
calibration certificate, delivered in a tough polypropylene
carry case – everything you need to start testing in one
package.
All models are rated to IP54, making them truly outdoor
instruments. They are designed to meet stringent safety
standards and are rated CAT IV 100 V. The ground testers
have been designed to be easy to use – a large selector
switch makes selection of 2, 3 or 4 pole tests easy with
gloved hands – and the design makes the fitting of shorting
links to perform 2-pole tests a thing of the past. A large,
clear, easy to read LCD and thumb sized test button
also make the instruments particularly well suited to the
outdoor conditions of ground testing. In addition to this
ease of use feature, the instruments automatically check
the connection and conditions of the P spike, C spike,
and also the level of ground noise, indicating the status
on the display. They also include a voltmeter to enable
measurement of ground voltage.
The DET4TD2 and DET4TR2 can measure resistance from
0.01 ohms to 20 kΩ, while the DET4TC2 and DET4TCR2
can measure resistance from 0.01 ohms to 200 kΩ, a key
capability for soil resistivity testing. Also, to allow accurate
testing in noisy environments, the instruments are capable
of rejecting noise up to 40 V peak to peak.
The DET4TD2 and DET4TC2 are powered by eight AA
batteries which are widely available and also give excellent
testing time – the status of these batteries is given by a bar
graph on the LCD display, allowing the operator to decide
when to change the batteries before they expire. The
DET4TR2 and DET4TCR2 are powered from rechargeable
DET4 Series
Earth/Ground Resistance & Soil Resistivity Testers
AA cells. The battery charger is built in and the instrument
is supplied with an AC/DC adapter. For all instruments, the
battery status is displayed using a bar-graph.
The DET4TC2 and DET4TCR2 include additional
capabilities. By using the optional ICLAMP the user can
augment the traditional fall-of-potential measurement
method with ART (Attached Rod Technique), which allows
electrode testing without disconnection and also leakage
current measurements down to 0.5 mA. A second optional
clamp, the VCLAMP, enables true stakeless (clamp-on)
measurements to be made in situations where driving
stakes is not practical.
The DET4TC2 and DET4TCR2 also feature a backlit
display, which extends the operational environment of
the instrument to cable cellars and other dark locations.
Finally, all units have selectable 25 V or 50 V output for
compliance with IEC 61557-5. The 25 V output is required
for testing in agricultural environments.
The maintenance of an adequate low resistance ground
connection is essential to both the protection and
performance of any electrical system. Ground testing
should be performed both upon installation, to meet
design specification, and periodically thereafter in order
to maintain service. All Megger models can also perform
bonding tests (using an ac signal), to determine that
adequate connection has been made from equipment to
the grounding system, and can perform soil resistivity
tests. This additional function can be used in prospecting,
locating, and designing new grounding electrodes and
systems. Furthermore, the addition of built-in current
clamp capability enables fall of potential testing of attached
grounds (ART) without lifting the utility connection and
the addition of voltage clamp technology enables stakeless
testing from the same instrument.
Grounding electrodes from simple to complex systems can
be tested, including:
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Primary and secondary electrical grounding systems
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Utility pole grounds
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Lightning protection systems
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Residential grounds
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Machinery safety grounds
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Computer and communication system grounds
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EMI/RFI system grounds
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Antenna and pedestal grounds
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CATV system grounds
Model DET4TCR2 shown performing the stakeless ground testing method
using only clamps.
APPLICATIONS
Proper grounding provides many varied benefits to both
people and facilities. It lessens the chance of injury due
to faulty installation, reduces the likelihood of damage
from lightning strikes and induced voltages, improves
the performance of computer, communication and other
sensitive equipment and protects against static electricity
from friction. Over time, ground systems can degrade or
become ineffective. Corrosion and weather influences
exert mechanical strain on ground rods and cause metallic
corrosion. Catastrophic events like lightning strikes or large
fault currents can cause instant degradation. In addition,
soil resistivity can change over time due to environmental
conditions and facility expansion can create different
ground system needs.
The risks from ground system deterioration include
potentially deadly electrical shock situations, plant-wide
equipment damage, disruption in the performance of
sensitive equipment and heat build-up on a single piece of
electrical equipment.
FEATURES AND BENEFITS
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Stakeless testing capability, which allows the operator
to use the instrument like a clamp-on tester in applications where the method is viable
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Attached Rod Technique capability, which allows fall
of potential testing without the need to disconnect the
ground rod
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Multiple, user selectable test frequencies allows the
operator to find the most effective frequency for making
the measurement
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200,000 Ω measurement range provides the ability to
measure the resistivity of any type of soil
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User selectable test voltage ensures that the units can be
used in agricultural environments
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Microprocessor control for improved error detection
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Clear, unambiguous warnings and error indications en-
sure the reliability of the reading and reduce test time
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Rugged, weatherproof case to IP54 makes the units truly
outdoor instruments
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Backlit LCD allows for testing in dark environments
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Noise rejection to 40 V pk to pk allows accurate testing
in noisy environments
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Testing kits and certificates supplied — everything
needed to start testing immediately
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Accuracy of 2% of reading enhances reliability of mea-
surements
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Voltmeter function included allows you to measure the
ground voltage and enhances operator safety
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CAT IV 100V provides increased operator safety
DET4 Series
Earth/Ground Resistance & Soil Resistivity Testers
SPECIFICATIONS
Resistance range: 0.01 to 200 kΩ autoranging
(0.01 to 20kΩ for models DET4TD2 and DET4TR2)
Resistance accuracy:
2P measurements 2% ±3 digits
3P measurements 2% ±3 digits
4P measurements 2% ±3 digits
ART measurements 5% ±3 digits
Stakeless measurements 7% ±3 digits
Maximum probe resistance:
DET4TD2 and DET4TR2
Rp limit: 100kΩ (50V output voltage)
Rc limit: 100kΩ (50V output voltage)
Limits reduced to 50kΩ for 25V output voltage
Limits reduced to 5kΩ for 0.01 Ω resolution
DET4TC2 and DET4TCR2
Rp limit: 200kΩ (50V output voltage)
Rc limit: 200kΩ (50V output voltage)
Limits reduced to 100kΩ for 25V output voltage
Limits reduced to 5kΩ for 0.01 Ω resolution
Earth voltage range: 0 – 100 V
Earth voltage accuracy: 2% ±2 V
2-wire test: Yes, all models
3-wire test: Yes, all models
4-wire test: Yes, all models
ART (Attached Rod Technique): DET4TC2, DET4TCR2
Stakeless test: DET4TC2 and DET4TCR2
Ground current range (with current measuring clamp):
0.5 mA to 19.9 A
Ground current accuracy: 5% ±3 digits
Display:
DET4TD2 and DET4TR2: 3-1/2 digit high contrast LCD
DET4TC2 and DET4TCR2: 3-1/2 digit high contrast LCD, backlit
Test frequency: 94, 105, 111 and 128 Hz
(128 Hz for DET4TD2 and DET4TR2)
Test voltage: 25 V or 50 V, user selectable (factory setting 50 V)
Test current: 450 micro-amps at 25 V or 50 V (selectable),
4.5 mA at 25 V
Noise rejection: 40V pk to pk
Noise check: Automatic
C spike check: Automatic
P spike check: Automatic
Battery type: 8 1.5 V AA cells (8 1.5 V AA NiMH rechargeable
cells – DET4TR2 and DET4TCR2)
Battery life: 3 hours, 700 consecutive tests
Safety: EN61010-1 CAT IV 100 V
Terminals: 4 mm plug type (test leads)
Ingress protection: IP54
EMC: Meets the requirements of EN61326-1:1998 for use in heavy
industrial areas, including amendment 1
Dimensions: 8 x 5.7 x 3.2 in. (203 x 148 x 78 mm)
Weight: 2.2 lb (1 kg)
Operating temperature range: 5º to +131º F (-15º to +55º C)
Storage temperature range: -40º to +158º F (-40º to +70º C)
Humidity: 95% RH non-condensing at 104º F (40º C)
Standards Compliance
Complies with the requirements of KEMA K85B.
Complies with the following parts of EN61557, “Electrical safety
in low voltage distribution systems up to 1000 V a.c. and 1500 V
d.c. - Equipment for testing, measuring or monitoring of protective
measures”.
Part 1 - General requirements
Part 5 - Resistance to earth
STAKELESS (CLAMP-ON) TESTING
The DET4TC2 and DET4TCR2 include stakeless, or
clamp-on testing capability. In effect, these models can
be operated in the same way as a clamp-on ground
tester, eliminating the need to disconnect the ground
under test and drive test probes in certain ground system
testing applications. This method is also useful when
there is insufficient space to perform a classic fall-ofpotential measurement. In addition the units can be used
to measure ground leakage or phase current.
The user simply clamps the optional ICLAMP (current
clamp) and VCLAMP (voltage clamp) around the ground
under test in the manner prescribed in the operator’s
manual and takes the reading. A defined test voltage is
injected into the system using the VCLAMP, inducing a
current, I, to flow and be measured by the ICLAMP. The
instrument then calculates the approximate resistance of
the ground under test.
The stakeless method is subject to the same limitations
faced by the traditional clamp-on ground tester. It is
effective only in situations with multiple grounds in
parallel and cannot be proofed like a fall-of-potential
test. In situations where the stakeless method reading is
questionable, a full fall-of-potential test is recommended.
The advantage of the DET4TC2 and DET4TCR2 is that the
units include both test methods in a single instrument,
making them the most versatile units available.
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