C-2 measuring clamps with a hard core are used to measure alternating currents. The maximum diameter of the tested conductor is 52 mm. They are terminated with a round 3-pin plug, compatible with Sonel MRU-100 (from no. 124588), MRU-101 (from no. 124488) devices, as well as MPI-510 and MPI-511. The use of clamps eliminates the need to disconnect control connections, significantly reducing the testing time. These clamps allow user to determine the type of current flowing through the tested earthing element and to check the resulting voltage drop. The measurement safety category of the presented product is CAT II 300 V.