I have what appears to be an open neutral problem. I'm getting 120 volts from neutral to ground. Funny thing though, the 3-wire plug-in tester shows hot & ground reversed.
I know nobody switched the wires, because the problem is intermittent, and sometimes it is OK.
Does anyone know the internal circuitry of the plug-in tester, and why it would show hot & ground reversed when it appears to be an open neutral?

Thanks,

John