BS 7671 Testing RCD’s - Regardless of the Type of RCD Test it as if it is an AC RCD at x1 ONLY Changes to BS 7671 under Amendment 2 of the 18th Edition of the Wiring Regulation requires RCD’s to only be tested on the AC setting regardless of the Type of RCD and at the rated residual operating current of the device. This simplifies the testing process so even if you have an A, B or F Type RCD you only need to test it on the AC setting of you MFT tester and at 1x its mA current rating with a maxim