Re: wall receptacles
Tests done with an outlet tester, obviously, are done with the power on, however, when it comes time to do the work, turn off the breaker feeding the outlet(s) in question, then test the outlet again with a volt meter to make sure it has been de-energized.
Originally Posted by JLMCDANIEL
Building on what Jack said, the key words "on screw", and make sure the wire is wrapped so that it tightens around the screw as the screw is tightened. Back stabbed outlets - those where the wire is just poked into a hole, can have/create loose connections. Also check that the wire nuts are tight and each wire within the nut is held firmly in the bundle by holding the cap and tugging each wire individually. The issue you're searching for may not necessarily originate at the outlet where you're getting the weird reading, it could be where it branches from the outlet upstream. Check each outlet on the circuit if correcting those in question doesn't cure the problem.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!