noun
insulation resistance tester; megohmmeter
A measuring instrument used to test the insulation resistance of electrical equipment and wiring. Also called a megohmmeter or 'megger' (brand name).
電気工事の前に、絶縁抵抗計で配線の絶縁を確認します。
Before electrical work, we check the insulation of the wiring with an insulation resistance tester.
Compound of 絶縁 (insulation), 抵抗 (resistance), and 計 (meter). A straightforward technical term.