Abstract: An electrical circuit tester includes a first testing device and a second testing device provided in a hand-held housing, each being electrically isolated from the other. Multiple light sources are electrically coupled to one of the first and second testing devices to provide a visual indication of the testing result. The first testing device includes a conventional three-prong plug extending out from the surface of the housing and configured to be inserted into a standard electrical receptacle. The second testing device includes one or more keyed cavities, each being designed to receive all or a portion of a plug into the cavity in only one orientation. Each cavity can include at least one blade prong that makes electrical contact with the plug when inserted into the cavity. Both the first and second testing devices can be operated simultaneously with separate sets of light sources providing separate testing indications for each.