Look for neat cables, solid grounding, and the right wire size. Each circuit should have its own breaker or fuse. Check for UL or CE marks and make sure everything follows local codes. Labels help you know what's what. The mapping process takes time but proves invaluable when. Having a map of your home's electrical circuits can help you quickly and easily identify the source of a problem. Guide to Electrical Hazards in buildings: inspection, detection, & repair advice. InspectAPedia tolerates no conflicts of interest. - Daniel. In this guide, we'll walk you through how to use a breaker box, how to identify parts like the main breaker, and even cover how electrical panels work—all in a clear, non-intimidating way.