This is governed by your state’s utility regulatory agency, such as a Board of Public Utilities. My state respects the ANSI C84.1 guideline, which calls for a ± 5 percent regulation of the nominal 120VAC service, or 114 volts minimum.
What is the lowest voltage acceptable ?
I live in an apartment building and the AC voltage is usually 121 VAC. Lately with the hot weather Con Edison has had problems in Northern Queens , New York. My voltage has been lower and fluctuating between 119 and as low as 109. Right now it’s 115. What is the lowest to safely power my system?