Anything below 108 is not good. I am currently at a seasonal site the summer. Pedestal voltage at 30amp outlet with no load is 115v which is low. On the weekends, it drops to 110. When I turned on my air conditioning, voltage under load at my wall outlet was as low as 98.
I did not like this so I bought a Hughes Autoformer to boost and regulate the voltage. With the Autoformer hooked up, I am now seeing voltage at 122 with no load at wall outlet and 117 with air conditioning running. I couldn't be more pleased. It was worth the $.