I'd have to dig out my surge guard specs , but if memory serves , low voltage cut out is 107 volts .
With only 109 , be cautious what you turn on as even a couple of small loads can trigger the shut down .
EDIT: A quick read of my manual gives range as 102 volts low and 132 volts high as operational range . Your system may vary.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.