Cable testing equipment: High Voltage Inc.’s OHM-CHECK™ Tester is designed to measure the extent of deterioration of a concentric neutral of a power cable. A concentric neutral is made up of many strands of round or flat wire helically wrapped around the cable insulation and usually grounded at both ends. It has multiple purposes. Severe problems can occur for a utility if this neutral has corroded to a point where it can no longer carry return currents and is not capable of returning fault currents from a fault location back to the grounded end of the neutral.
This concentric neutral may have 6 – 20 strands of aluminum or copper wire wrapped around the insulation. Whenever a strand corrodes and opens, there is a very incremental and measureable change to the neutrals resistance. This is what the instrument measures; how much of the neutral remains intact.