absolutely monitor the volts with a meter,dont trust the dial!
i had the same problem with mine,the actual volts coming out dont match the dial,but hey with the way wall volts vary around here its no surprise to me.
i pretty much have my variac set where its measuring 110 to 112 or so, if the wall volts go way up to say 128 at least what is coming out of the variac is still under 120 volts with the same setting.
so i guess i have the variac set to about 10 volts less than wall volts all of the time

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