The Fluke 1623 and 1625 are distinctive earth ground testers that can perform all four types of earth ground measurement. Specifically, the Fluke 1623 and 1625 testers are able to measure earth ground loop resistances using only clamps – called Stakeless testing. This method doesn’t require the use of earth ground stakes or the disconnection of ground rods.

Testing Methods

3- and 4-Pole Fall of Potential – standard earth ground testing using two ground stakes Selective testing – without disconnecting ground rods, a technician can measure ground resistance using a combination of stakes and a clamp. Stakeless testing – innovative solution using only clamps, instead of ground stakes, to measure earth ground loop resistance.

The Fluke 1625 offers these advanced features

Automatic Frequency Control (AFC) – identifies existing interference and chooses a measurement frequency to minimize its effect, providing a more accurate earth ground value. R* measurement – calculates earth ground impedance at 55 Hz to more accurately reflect the earth ground resistance that a fault-to-earth ground would see. Adjustable limits – for quick test result verification.

Advanced technology for all your earth ground testing applications

1623

One-button measurement concept 3- and 4-pole earth ground measurement 2-pole resistance measurement AC Selective testing, no disconnection of ground conductor (1 clamp) Stakeless testing, quick ground loop testing (2 clamps) Measuring frequency 128 Hz

1625

3- and 4-pole earth ground measurement 4-Pole soil resistivity testing 2-pole resistance measurement AC 2- and 4-pole resistance measurement DC Selective testing, no disconnection of ground conductor (1 clamp) Stakeless testing, quick ground loop testing (2 clamps) Earth impedance measurement at 55 Hz Automatic frequency control (AFC) (94, 105, 111, 128 Hz) Measuring voltage switchable 20/48V Programmable limits, settings Continuity with buzzer

RA 3-pole ground resistance measurement (IEC 1557-5)
Measuring Voltage	Fluke 1623  Vm = 48 V ac Fluke 1625  Vm = 20/48 V ac
Short circuit current	Fluke 1623  > 50 mA Fluke 1625  250 mA ac
Measure frequency	Fluke 1623  128 Hz Fluke 1625  94, 105, 111, 128Hz
Resolution	Fluke 1623  0.001 Ω to 10 Ω Fluke 1625  0.001 Ω to 100 Ω
Measuring range	Fluke 1623  0.001 Ω to 19.99 kΩ Fluke 1625  0.001 Ω to 299.9 kΩ
Intrinsic error	Fluke 1623  ± (2 % of reading + 3 digit) Fluke 1625  ± (2 % of reading + 2 d)
Operating error	Fluke 1623  ± (5 % of reading + 3 d) Fluke 1625  ± (5 % of reading + 5 d)

RA 4-pole ground resistance measurement (IEC 1557-5)
Measuring Voltage	Fluke 1623  Vm = 48 V ac Fluke 1625  Vm = 20/48 V ac
Short circuit current	Fluke 1623  > 50 mA Fluke 1625  250 mA ac
Measure frequency	Fluke 1623  128 Hz Fluke 1625  94, 105, 111, 128Hz
Resolution	Fluke 1623  0.001 Ω to 10 Ω Fluke 1625  0.001 Ω to 100 Ω
Measuring range	Fluke 1623  0.001 Ω to 19.99 kΩ Fluke 1625  0.001 Ω to 299.9 kΩ
Intrinsic error	Fluke 1623  ± (2 % of reading + 3 d) Fluke 1625  ± (2 % of reading + 2 d)
Operating error	Fluke 1623  ± (5 % of reading + 3 d) Fluke 1625  ± (5 % of reading + 5 d)

RA 3-pole ground resistance measurement with current clamp
Measuring Voltage	Fluke 1623  Vm = 48 V ac Fluke 1625  Vm = 20/48 V ac
Short circuit current	Fluke 1623  > 50 mA Fluke 1625  250 mA ac
Measure frequency	Fluke 1623  128 Hz Fluke 1625  94, 105, 111, 128Hz
Resolution	Fluke 1623  0.001 Ω to 10 Ω Fluke 1625  0.001 Ω to 10 Ω
Measuring range	Fluke 1623  0.001 Ω to 19.99 kΩ Fluke 1625  0.001 Ω to 29.99 kΩ
Intrinsic error	Fluke 1623  ± (7 % of reading + 3 d) Fluke 1625  ± (7 % of reading + 2 d)
Operating error	Fluke 1623  ± (10 % of reading + 5 d) Fluke 1625  ± (10 % of reading + 5 d)

RA 4-pole selective ground resistance measurement with current clamp
Measuring Voltage	Fluke 1623  Vm = 48 V ac Fluke 1625  Vm = 20/48 V ac
Short circuit current	Fluke 1623  > 50 mA Fluke 1625  250 mA ac
Measure frequency	Fluke 1623  128 Hz Fluke 1625  94, 105, 111, 128Hz
Resolution	Fluke 1623  0.001 Ω to 10 Ω Fluke 1625  0.001 Ω to 10 Ω
Measuring range	Fluke 1623  0.001 Ω to 19.99 kΩ Fluke 1625  0.001 Ω to 29.99 kΩ
Intrinsic error	Fluke 1623  ± (7 % of reading + 3 d) Fluke 1625  ± (7 % of reading + 2 d)
Operating error	Fluke 1623  ± (10 % of reading + 5 d) Fluke 1625  ± (10 % of reading + 5 d)

Stakeless ground loop measurement
Measuring Voltage	Fluke 1623  Vm = 48 V ac Fluke 1625  Vm = 20/48 V ac
Measure frequency	Fluke 1623  128 Hz (125 Hz on request) Fluke 1625  94, 105, 111, 128Hz
Noise current (Iext)	Fluke 1623  Max. Iext = 10 A (ac) (RA < 20 Ω)  Max. Iext = 2 A (ac) (RA < 20 Ω) Fluke 1625  Max. Iext = 3 A
Resolution	Fluke 1623  0.001 Ω to 0.1 Ω Fluke 1625  0.001 Ω to 10 Ω
Measuring range	Fluke 1623  0.001 Ω to 199.9 kΩ Fluke 1625  0.001 Ω to 29.99 kΩ
Intrinsic error	Fluke 1623  ± (7 % of reading + 3 d) Fluke 1625  ± (7 % of reading + 2 d)
Operating error	Fluke 1623  ± (10 % of reading + 5 d) Fluke 1625  ± (10 % of reading + 5 d)

Environmental Specifications
Working temperature	-10 °C to +50 °C
Operating Temperature	0 °C to +35 °C
Nominal temperature	+18 °C to +28 °C
Storage Temperature	Fluke 1623  -20 °C to +60 °C Fluke 1625  -30 °C to +60 °C
Climatic class	C1 (IEC 654-1), -5 °C to + 45 °C, 5 % to 95 % RH
Protection type	IP56 for case, IP40 for battery door according to EN 60529

Safety Specifications
Safety Rating	CAT II, 300 V

Mechanical & General Specifications
Display	Fluke 1623  1999 digit LCD – display with special symbols, digit height 25 mm, fluorescent backlight Fluke 1625  2999 Digit LCD – 7 segment liquid crystal display with special symbols and backlight
Size	133 mm x 187 mm x 250 mm
Weight	Fluke 1623 + 1625  1.1 kg (including batteries)
Warranty	Two years
Battery Life	Fluke 1623  Typical > 3000 measurements Fluke 1625  Typical 3000 measurements (RE+RH ≤ 1 kΩ)  Typical 6000 measurements (RE+RH ≤ 10 kΩ)