Electrical Polarity Outlet Receptacle Tester
This electric receptacle tester safely detects ungrounded lines and disconnected or interchanged neutral and hot wires! This handy receptacle tester is especially important when using hi-tech equipment such as computers, stereos and TVs. Just plug the electric receptacle tester to instantly diagnose plugs! The built-in indicators light up to tell you if the plug is safe to use so you can use your electronics with peace of mind.
- Instantly diagnoses plugs
- Indicators light up when unit is plugged into the wall
- Important when using hi-tech equipment
A receptacle tester or outlet tester is a device used to verify that an AC wall outlet is wired properly. The tester itself is small device containing a power plug and several indicator lights. Although a multimeter could be used to perform a series of tests which would give the same results, an outlet tester can perform the entire array of tests by simply plugging the device into the outlet once and observing the state of the lights. The tester performs several tests at once but the tests themselves essentially fall into two categories: tests which determine that the outlet has power connected, and tests which determine that the outlet is properly wired for safe operation.
||Electric Receptacle Tester
|Operating Voltage Range
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's wiring. There are two primary reasons for testing this. First, some devices must have a specific prong connected to the live connection or damage to the device could result. Second, and more importantly, if the live wire is connected but the neutral or ground wire is not, a dangerous situation could be created by preventing safety mechanisms from operating properly. Furthermore the ground wire is typically attached to the case of an electrical device as a safety precaution to carry away current if the insulation on the wires is damaged and the case becomes charged. Although this is an important safety feature on many devices, if the outlet is improperly wired with the ground plug connected to the live wire the safety mechanism has the opposite effect and charges the outside of the device creating the potential for an electric shock for anyone touching the device.
Note also that simple three light testers cannot detect two potentially serious house wiring errors: (1) neutral and ground reversed at the receptacle. (2) a "bootleg" ground, where the neutral and ground pins have been connected together at the receptacle. (Done by someone to attempt to fool the three light tester, typically if 3-prong outlets have been retrofitted to an old house with only two physical wires in the conduit.)
However by using the receptacle tester first, then a multimeter, these two errors can be detected: With the meter, look for low (but not zero) resistance and volts between neutral and ground. (Zero ohms is a sure sign of a bootleg job.) For the neutral-ground reversal test, next put some load on the same outlet circuit (e.g. a 100w incandescent lamp plugged into the other socket of the outlet), the meter should show a higher voltage between hot and ground, than between hot and neutral. This is because of the voltage drop due to the load. If it is the reverse situation, then you likely have a receptacle with neutral and ground reversed.
It is required that you test the polarity of you wall outlets before using an inverter like the ones shown below: