How To Test an Electrical Outlet
It is surprising the number of times an electrician will be called out for a non-functioning outlet only to "fix it" by flipping a switch. So, the first thing to do is turn on any wall switches that may control an outlet. Another thing to check is that the circuit breaker or fuse is intact and that no GFCI outlet controlling the branch circuit has tripped.
Working with live electrical circuits can be hazardous. Do not attempt this measurement without the proper tools and safeguards. Always test your test equipment for proper operation before use.
Testing an outlet can be as simple as plugging in a light to see if it goes on. Of course, always test your test equipment first. If that light doesn't work and you test an outlet and assume there is no current because the light doesn't go on, you may be in for a shock.
A more thorough way to test electrical outlets involves the use of an outlet tester. This device will not only indicate if the outlet has power, it will also indicate if the outlet is grounded and whether the hot, common or ground wires are reversed.
The device could not be easier to use and costs only a few dollars. Generally, you plug the device in and note the pattern of the lights. The legend printed on the device describes what the lights indicate. Be sure to follow all of the instructions provided by the manufacturer.
If an outlet is identified as being miswired or does not have proper ground, you should not use the outlet until the problem is resolved. In the case of a miswired outlet or absent ground, the problem may occur at the problem outlet or somewhere else in the branch circuit. Do some detective work to determine the extent of the problem before attempting any repairs.