The Ultimate Guide to Ground Resistance Testing: Comparing AEMC Ground Testers
Author: James Osborne Date Posted:10 May 2025
Ground resistance testing is a crucial part of any electrical safety program, especially in applications involving power distribution systems, substations, lightning protection, or telecommunications. Proper grounding ensures excess electrical current safely dissipates into the earth, preventing equipment damage, injury, or fire.
In this comprehensive guide, we'll explore:
- What ground resistance testing is and why it matters
- The different methods of ground resistance testing
- A side-by-side comparison of some of the most trusted testers in the industry: AEMC 6471, 6472, 4620, 4630, 6422, and 6424
What is Ground Resistance Testing?
Ground resistance testing measures how efficiently a grounding system can conduct electricity to the earth. This is essential for:
- Protecting people from electric shock
- Preventing equipment damage
- Complying with electrical codes and standards (such as IEEE 81, NEC, and IEC)
- Ensuring lightning protection systems work effectively
Ground Resistance Testing Methods
There are several methods to test ground resistance:
1. 3-Point Fall-of-Potential Test
The traditional and most accurate method using auxiliary electrodes (stakes). Best for system commissioning or installations with little electrical noise.
2. 4-Point Soil Resistivity Test
Used to measure soil resistivity, important for grounding system design.
3. Selective Testing
Uses the clamp-on method to eliminate the need to disconnect the ground system.
4. Stakeless Testing (Clamp-on Testing)
Fast and convenient for systems with multiple parallel grounds.
Comparing AEMC Ground Resistance Testers
AEMC is a leading manufacturer of high-quality electrical test equipment. Here's a detailed comparison of their ground resistance testers, broken down by model type.
AEMC 6471 vs AEMC 6472
|
Feature |
AEMC 6471 |
AEMC 6472 |
|
Test Types |
2P, 3P, 4P, Selective, Stakeless |
All 6471 features + advanced capabilities |
|
Soil Resistivity |
Yes |
Yes |
|
Clamp-on Compatible |
Yes |
Yes |
|
Earth Coupling |
Yes |
Yes |
|
Bond Testing |
Yes |
Yes |
|
Measurement Current |
>200mA |
>200mA |
|
Communication |
USB |
USB |
|
Display |
LCD, backlit |
LCD, backlit |
|
Advanced Capabilities |
Soil resistivity auto calculation |
Potential measurement at stakes |
|
Use Case |
Contractors, utilities |
Power utilities, industrial sites, engineers |
Verdict:
Choose the 6471 for standard professional ground testing and reporting. Choose the 6472 for advanced diagnostics, analysis, and reporting.
AEMC 4620 vs AEMC 4630
|
Feature |
AEMC 4620 |
AEMC 4630 |
|
Test Type |
3P and 4P testing |
3P and 4P testing |
|
Soil Resistivity |
Yes (not calculated) |
Yes (not calculated) |
|
Power Source |
Battery operated |
Rechargeable battery |
|
Measurement Range |
0.01 Ω to 2000 Ω |
0.01 Ω to 2000 Ω |
|
Display |
Digital |
Digital |
|
Enclosure |
Rugged, weather-resistant |
Heavy-duty IP65 rated |
|
Ease of Use |
Manual operation |
Includes features such as single push button start |
Verdict:
The 4620 is perfect for basic, battery-powered field tests. The 4630 is designed for tougher environments and frequent use with a rugged case and rechargeable batteries.
AEMC 6422 vs AEMC 6424
|
Feature |
AEMC 6422 |
AEMC 6424 |
|
Test Method |
Digital 3P Testing |
Digital 3P Testing |
|
Display |
Multi Line LCD |
Multi Line LCD |
|
Test Voltage |
Fixed 10V |
Fixed 10V |
|
Battery |
AA batteries x 6 |
AA batteries x 6 |
|
Soil Resistivity |
No |
No |
|
Portability |
Compact, lightweight |
Compact with more features |
|
Ideal Use |
Budget-conscious testing |
Existing earth testing (3P) |
Verdict:
The 6422 is ideal for occasional, budget-friendly testing. The 6424 offers digital precision and modern features for regular professional use.
Model Summary Table
|
Model |
Test Types |
Power |
Display |
Advanced Features |
Ideal For |
|
6471 |
All major types incl. clamp |
Rechargeable |
Full Digital |
Leakage, coupling, bonding |
Utilities, inspectors |
|
6472 |
All incl. diagnostics |
Rechargeable |
Full Digital |
As per 6471 |
Engineers, industrial |
|
4620 |
3P/4P |
Battery |
Digital |
Soil resistivity |
Contractors, electricians |
|
4630 |
3P/4P |
Rechargeable |
Digital |
Weatherproofing |
Utilities, field techs |
|
6422 |
Basic testing |
Battery |
Digital |
Compact |
Entry-level users |
|
6424 |
Auto testing |
Battery |
Digital |
2-Wire bond testing, 3P |
Electricians & Simple use |
Conclusion: Choosing the Right Tester
When selecting a ground resistance tester, consider:
- Environment – Wet or noisy conditions? Go rugged or advanced.
- Frequency of Use – Regular testing requires durability and ease.
- Compliance – For large infrastructure or compliance-driven industries, invest in models like the 6472.
- Budget – AEMC offers models from entry-level to premium for every budget.
Whether you're a contractor performing routine maintenance or a power engineer verifying complex grounding systems, AEMC’s lineup ensures accurate and reliable testing.
Need Help Choosing?
Looking to purchase an AEMC tester or need further guidance? Reach out to a specialist or authorized distributor like Testrix Systems for expert advice and competitive pricing.
