This seems to be an unusually frequent subject in online electrical message boards.
The ANSI-standard [C84.1-1995 on your scorecards] acceptable voltage range for a 120-volt base is on the order of 110-126 volts, corresponding to about +5-8%.
C84.1 is sort of a treaty hammered out by utilities and appliance/equipment manufacturers, and gets quietly referenced in various ‘official’ documents by both groups.
Some electrical professionals miss an important aspect of power demand for voltage variations from nameplate ratings. Resistive loads [incandescent lamps & heaters] are effectively constant impedance, so that intentional or incidental increase of voltage produces higher real-power [watt] dissipation and requisite energy use. OTOH, within limits, things inductive [motors/solenoids] act more like constant apparent-power [voltampere] devices, so that—to a degree—higher voltage operation produces lower load current. The subject of voltage/power/energy relationships has been studied to a precise degree by utilities and equipment producers. Although it is generally figured {off-the-cuff} that lower voltage translates to reduced energy use, this statement is by no means chiseled in stone. In fact, one study of voltage reduction by a utility in a Scandinavian country showed—for resistance heat over a day’s time—energy use remained essentially flat with changes in voltage because the increased heater run time in building heat systems ‘compensated’ for change in the decreased instantaneous power demand. {However interesting to me, I do not work for a utility.} Utilities unofficially affirm that voltage-control studies are inconclusive.
