One centimetre here and there is really not inconsequential, use an electric measuring tool to be safe. You get great flexibility since it runs on a battery and lacks a cord that c
Amazon
BEHA AMPROBE AMP-210-EUR AC TRMS Clamp Meter, 600 A, jaw 30 mm
Conrad Electronic
Beha Amprobe AMP-210-EUR Clamp meter, Handheld multimeter Digital CAT III 600 V Display (counts): 6000