Fluke 1621 GEO Earth Ground Tester

The 1621 is an easy-to-use earth ground tester that is your first line of defense in detecting reliable ground connections.





The Fluke 1621 is an easy-to-use earth ground tester. For ground resistance testing, the 1621 is the first line of defense in detecting reliable ground connections. The unit features basic ground testing methods including 3-pole Fall-of-Potential as well as 2-pole ground resistance tests. Its convenient size, rugged holster, and large, clear LCD display make it an ideal field earth ground tester, for most electrical grounding work environments. With a simple user interface and intuitive functionality, the Fluke 1621 is a handy grounding tool for electrical contractors, utility test engineers, and earth ground specialists.


  • Easily capture values with single-button operation
  • 3-pole Fall-of-Potential earth testing for basic measurements
  • 2-pole resistance measurements for added versatility
  • Ensure accurate measurements with automatic ‘noise’ voltage detection
  • Hazardous voltage warning offers increased user protection
  • Clearly read and record data with a large, backlit display
  • Rugged holster and design for tough work environments
  • Portable size allows for easy transportation
  • Instantly be alerted to measurements outside of your set limit, when you use the adjustable limit setting
  • 600 V Cat II


General Specifications
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 one year
Measuring rate 2 measurements/second
Battery1 One 9 volt alkaline (LR61)
Battery condition LO-BAT is displayed if voltage drops below 6.5 V
Voltages Between jacks H/C2 and E/C1 250 Veff maximum (effective voltage)
Between jacks S/P2 and E/C1 250 Veff maximum
Climatic class VDE/VDI 3540 RZ (conforming to KWG as per DIN 40040, 4/87)
Temperature performance2 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 (+68°F to +140°F)
Reference +23°C ±2°C (+73°F ±4°F)
Temperature coefficient ±0.1% of range per degree Kelvin
Safety IEC/EN 61010-1, 600 V CAT II, pollution degree 2
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 cm3
Electrical Specifications
Maximum deviations E1Influence factor Position
E1Deviation influence 0%
E2Influence factor Supply voltage
E2Deviation influence 0%
E3Influence factor Temperature E3
E3Deviation influence 2.3%
E4Influence factor Serial interference voltage (20 V)
E4Deviation influence 0.6%
E5Influence factor Probe- and auxiliary probe resistance
E5Deviation influence 10%
Test voltage 3.7 kV
Protection type IP 40; IEC/EN 60529
Electromagnetic compatibility Emission IEC/EN 61326 Class B
Immunity IEC/EN 61326 Annex C
RE 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/EN 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
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)
Automatic changeover of resolution RH < 7 kΩ
Resolution 0.01 Ω
RH < 50 kΩ
Resolution 0.1 Ω
RH > 50 kΩ
Resolution 1 Ω
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
Measuring Range
0.15 Ω to 20 Ω Resolution 0.01 Ω
Display range 0 to 19.99 Ω
200 Ω Resolution 0.1 Ω
Display range 20 to 199.9 Ω
2 kΩ Resolution 1 Ω
Display range 200 to 1999 Ω
Intrinsic Uncertainty ±(6% of measured value + 5D)
Operating uncertainty IEC 615573 ±(18% of measured value + 5D)
1. If the tester is not going to be used, or is being stored for a long period, remove the battery and store separately from the tester to avoid damage from battery leakage.
2. The four temperature ranges for the tester exists to satisfy European Standards requirements; the instrument can be used over the full working temperature range by using the temperature coefficient to calculate accuracy at the ambient temperature of use.
3. Covers all deviations caused by influence quantities E1–E5. If the deviation E4 caused by high probe or auxiliary probe resistance is higher than specified flashes. Measured values are outside of the specified operating uncertainty.


Model Name Description
Fluke 1621 Fluke 1621 GEO Earth Ground Tester

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


Cables & Hardware
Model Name Description
Fluke GEO Fluke GEO Earth Ground Cable Reel 25 M Wire
Fluke GEO Fluke GEO Earth Ground Cable Reel 50 M Wire
Cases & Holsters
Model Name Description
Fluke-CXT280 Fluke CXT280 Extreme Case


Knowledge and Information

1621 Users Manual Download
1621 Addendum Download
1621 Statement of Memory Volatility Download
Application Notes
Checking ground electrode impedance for commercial, industrial and residential buildings Download
How to use cable and pole earth ground testers Download
Maintaining a solid ground Download
Principles of earth grounding Download
Data Sheets
Data Sheet for Fluke 1621 Download
Earth Ground Resistance – Principles, Testing Methods and Applications Download
Fluke 1621/1623/1625 Virtual Demo Download