Neutral Resistance Tester


The Ω-Check® concentric neutral resistance tester (Model OCK-30) is unique and useful. It injects an AC current through a live cable neutral and measures the voltage drop to calculate the resistance of that neutral. Based on previous data of the cable under test, the machine compares the measured data to that of a perfect cable to determine the level of neutral deterioration, or how many concentric neutral strands have opened.

How good is the neutral from end to end?

A concentric neutral is composed of many strands of round or flat wire helically wrapped around the cable insulation and usually grounded at both ends. Severe problems can occur if the neutral has corroded to the extent that it can no longer carry return and/or fault currents. Other problems can result, like stray voltage and voltage fluctuation, and impediments to diagnostic tests such as VLF-TD and VLF-PD. Before cable rejuvenation (injection) is considered, the neutral integrity must be qualified.

Uses for the Ω-Check® Tester

  • Test integrity of neutrals to carry return and fault currents
  • Measure % of neutral intact before performing cable injection
  • Check neutrals before tan delta & partial discharge testing
  • Reduce voltage fluctuations and improper relay operation
  • Reduce shock hazards by finding and replacing bad neutrals
  • Verify continuous neutral exists before fault locating cable
  • Measure resistance of substation ground cables

Model OCK-30

Input: 120 V AC @ 15 A, 60 Hz
Output: 0-48 V RMS, 0-30 A RMS
Measures: V, I, R (Ω)
R (Ω/100’)
% of neutral intact
Power factor
Data Export: SD card on panel
Output Termination: Two 500′ reels


Ω-Check® is a registered trademark of High Voltage, Inc. ®