The vast majority of your electrical systems are behind walls and unless your outlets are hot to the touch or your lights are browning out, you might not be able to tell there’s a problem.
Read up on Signs You Need To Call An Electrician.
There is a handy device called outlet tester, sometimes receptacle tester, that can analyze the wiring functionality behind your outlets. The apparatus itself is a small device containing a power plug and several indicator lights. At its most basic, the outlet tester can verify that the outlet provides power. In order for an electrical outlet to function, it must have a live or “hot” connection to a varying electrical voltage, as well as a neutral connection to complete the circuit. If either of these is not hooked up, or is damaged in some way, then the outlet will not function at all.
The much more important role of the outlet tester is to not only verify that electricity is present in the outlet but that the outlet is properly wired, with each plug being connected to the proper wire in the building. There are two reasons for this: first, some devices must have a specific prong that connects to the live wire or the outlet could damage the device; second, and more importantly, if the live wire is connected but the neutral or ground wire is not, a dangerous situation could arise by preventing safety mechanisms from operating properly.
However, keep in mind that these testers cannot detect two potentially serious house wiring errors: neutral and ground reversal at the receptacle, and a “bootleg” ground, where the neutral and ground pins have been connected together at the receptacle. Some of these wiring errors are meant to hoodwink an outlet tester. In this case, if there is a heavy suspicion something is not right with the outlet and the outlet tester shows all is okay, we recommend a multimeter that will show voltage.
These testers are especially important when you are looking at a new home. A home inspector or potential buyer may not be able to spot what could become an expensive wiring problem.
