Clamp-On Ground Resistance Tester: Fast Non-Invasive Grounding Measurement Without Disconnecting

How Clamp-On Ground Resistance Testing Works

A clamp-on ground resistance tester measures the resistance of grounding systems without the need to disconnect ground rods or install auxiliary test stakes. The instrument works by clamping around a ground conductor and injecting a known signal, then measuring the loop resistance of the complete ground circuit. This non-invasive method provides fast, safe measurements that would otherwise require time-consuming stake driving and conductor disconnection.

This testing method is particularly effective for multi-grounded systems where multiple ground rods are connected in parallel, such as utility distribution systems, telecommunications facilities, and commercial building ground rings. The clamp-on method measures the individual ground rod resistance within the parallel network, something that conventional fall-of-potential testing cannot do without disconnecting each rod.

Standard Jaw Clamp Testers: EK-B200 Series

The EK-B200 series features a rectangular jaw opening of 55x32mm that accommodates most standard ground conductors and bus bars. The series starts with the entry-level EK-B200X offering resistance measurement from 0.01 ohm to 500 ohm with 99-group data storage and audible/visual alarm when readings exceed preset thresholds.

The EK-B200A expands the range while maintaining the same specifications, and the EK-B200 extends measurement capability to 1000 ohm for applications requiring wider range coverage. The EK-B200C adds leakage current measurement (0.0mA to 30.0A), making it a multi-function instrument for both ground resistance and leakage current assessment.

For professionals requiring data connectivity, the EK-B200A+, EK-B200+, and EK-B200C+ models add Bluetooth communication supporting national grid protocol standards, expanded 500-group data storage, and configurable alarm settings. These Bluetooth-enabled models feature a larger 65x32mm jaw opening to accommodate bigger conductors, and support wireless data transfer to smartphones and tablets for field reporting.

Round Jaw Clamp Testers: EK-B210 Series

The EK-B210 series uses a round jaw design with a 32mm diameter opening, specifically optimized for round conductors and ground rods. The round jaw provides better contact and more consistent measurements on cylindrical conductors compared to rectangular jaw designs.

The series mirrors the B200 lineup with standard models (EK-B210A, EK-B210, EK-B210C) offering basic measurement and storage, plus Bluetooth-enabled models (EK-B210+, EK-B210A+, EK-B210C+) with enhanced connectivity and expanded capabilities. The multi-function EK-B210C+ combines ground resistance measurement up to 1200 ohm with leakage current detection up to 30A and full Bluetooth connectivity.

Combined Stake and Clamp Testing: EK-B230 Series

The EK-B230 series represents the most versatile ground resistance testing platform, combining multiple measurement methods in a single instrument. These testers support 2-wire, 3-wire, and 4-wire fall-of-potential methods, selective testing, and clamp-on testing, along with soil resistivity measurement, ground voltage, and ground current functions.

The EK-B230 offers ground resistance measurement up to 20.00 kohm with a 65x32mm clamp jaw, lithium battery power, USB interface, and Bluetooth connectivity with a mobile app. The EK-B230B extends the resistance range to 200.00 kohm for demanding applications such as telecommunications facility testing and high-resistance soil conditions.

These combined instruments eliminate the need to carry separate clamp-on and stake-type testers to the job site. Technicians can use the clamp-on method for quick screening of multi-grounded systems, then switch to the 3-wire or 4-wire method for detailed individual ground rod testing when anomalies are detected.

Selecting the Right Clamp-On Tester

For routine ground resistance surveys in utility and commercial environments, the standard EK-B200 or EK-B210 series provides reliable, cost-effective measurement. Choose the rectangular jaw (B200) for flat conductors and bus bars, or the round jaw (B210) for round conductors and ground rods.

When leakage current measurement is needed alongside ground resistance, select the C-suffix models (EK-B200C, EK-B210C, or their Bluetooth variants). For maximum versatility and the ability to perform both clamp-on and stake-type testing, the EK-B230 series offers the most comprehensive measurement capability in a single instrument.

Bluetooth-enabled models are recommended for any professional testing program where data documentation, reporting, and remote monitoring are important. The wireless data transfer eliminates manual recording errors and streamlines the reporting workflow from field measurement to final documentation.