Earth ground tester calibration involves verifying and adjusting the accuracy of instruments used to measure the resistance of grounding systems, which are critical for electrical safety. The process typically includes comparing the tester’s readings against certified reference standards, checking measurement ranges, inspecting probes and connections for wear or damage, and making necessary adjustments to correct deviations. Regular calibration ensures reliable and precise ground-resistance measurements, supports compliance with industry and safety standards, prevents hazardous conditions due to improper grounding, and provides traceable documentation for quality assurance, maintenance records, and regulatory audits.