"Needed a RCD Socket to replace an existing one. This one is good value but Trips out my main Consumer Unit when the test button is pressed. So no use to me and will be returning. Other reviewers have complained of the same issue on other Safety Sure RCD's. The one it replaced didn't have this issue when it worked, nether does the one in my garden or the plug in type. A qualified Electrician has checked the install which is to standard. Shame as the price is good."