Does my RCD need to be tested and how often?

All RCDs have a test button marked T or Test. You should press this every six months to confirm the device is working. When you press the button, the RCD should trip immediately — cutting the power to the circuits it protects. To reset it, press the lever down and back up again. If the RCD does not trip when you press the test button, the device may have failed and is no longer protecting you — call a qualified electrician immediately.