Fluke 1621 Earth Ground Clamp


Fluke 1621 Earth Ground Tester

Fluke 1621 Earth Ground Tester


The Fluke 1621 Earth Ground Tester (the Product or Tester) is an easy-to-use instrument for measuring the resistance to earth ground of a specified earth ground electrode. The Tester can perform a 3-pole fall-of-potential test conforming to IEC 61557-5. The Tester can also perform ac resistance testing.

To further simplify and increase the probability of an accurate measurement in the 3-pole mode, the Tester measures the resistance of the probe and auxiliary electrode to verify that they are within prescribed limits. The Tester also tests for stray interference voltage (noise) and indicates if the value is too high to take a proper measurement.

The Tester features a lighted LCD display, automatic shut-off, and a limits mode for setting maximum resistance readings.

The following accessories are shipped with your Product:

  • Users manual
  • Two measuring leads with alligator clips, 2 m (6 ft)
  • One battery, 9 V alkaline (IEC 6LR61)
  • One protective holster, yellow


Measuring functions 3-pole earth ground resistance, 2 pole AC resistance of a conductor Interference voltage
Intrinsic error Refers to the reference temperature range and is guaranteed for 1 year
Measuring rate 2 measurements / second
Battery condition LO-BAT is displayed if voltage drops below 6.5 V
Between jacks H/C2 and E/C1 250 Veff maximum (effective voltage)
Between jacks S/P2 and E/C1 250 Veff maximum
Temperature ranges Working: -10 °C to +50 °C (+14 °F to +122 °F)

Operating: 0 °C to +35 °C (+32 °F to +95 °F)

Storage:  -20 °C to +60 °C (-4 °F to +140 °F)

Reference:  +23 °C ± 2 °C (+73 °F ±4 °F)

Temperature Coefficient ±0.1 % of range per degree Kelvin
Safety IEC 61010-1, 600VCATII, pollution degree 2
Test voltage 3.7 kV
Dimensions 113 x 54 x 216 mm (4.5 x 2.1 x 8.5 in), including holster
Weight 850 g (1.9 lb), including standard accessories, Volume approximately 600 cm
R E Resistance Measurement
Measuring method Current-voltage measurement with improved cross-talk attenuation, no compensation of measuring lead resistance, with probe (3-pole) or without probe (2-pole) as per IEC 61557-5
Open circuit voltage 23 to 24 V ac
Short circuit current >50 mA ac
Measuring frequency 128 Hz
Maximum permissible overload 250 Veff





Resolution Display Range Intrinsic





IEC 61557*

0.15 Ω to 20 Ω 0.01 Ω 0 Ω to 19.99 Ω ±(6 % of measured value + 5D) ±(18 % of Measured value + 5D)
200 Ω 0.1 Ω 20 Ω to 199.9 Ω ±(6 % of measured

value + 5D)

±(18 % of Measured value + 5D)
2 kΩ 1 Ω 200 Ω to 1999 Ω ±(6 % of measured

value + 5D)

±(18 % of Measured value + 5D)


Measuring time 8 seconds (average from when START is pressed)
Limit input Tester retains set value even if instrument is turned off (assuming battery power supply is sufficient)
Interference Voltage Display DC + AC
Vmax 30 Veff
Common mode rejection >80 dB at 50 Hz and 60 Hz
Ri 680 kΩ
Measuring uncertainty <10 % for pure ac and dc signals



Weight 0.85 kg
Dimensions 113 × 54 × 216 mm