Depends on how serious you want to get. There are devices that allow you to monitor your incoming AC with an oscilloscope. This allows you to check your noise along the various "legs" on the circuit, sometimes simultaneously. While doing this, you can have a meter that measures the average line voltage. You can also have a digital meter that captures and stores the peak voltage. You can also have a device that allows you to listen to the noise on the line. The simplest and easiest to use would be the last device, which can be purchased from Audioprism and it is called an "AC Noise Sniffer". Like i said, how far do you want to go ??? : ) Sean
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