That "117" volt ideal is the RMS value for a 60-Hz sinewave only. Are you measuring your 300 output at 60 Hz, no multiwave, no higher frequency settings? Otherwise the reading will be higher.
Consumer Alert PS300 actual voltage
I was re-reading the follow-up review of the PS300 power plant with Mulit-wave. There was mention of an item I remember reading, but I never followed it up. The issue is in the voltage output. On the earlier models (I'm only assumong this was corrected) the voltage reads out as 117, but when actually measured by the reviewer with a volt meter it turned out the voltage was actually 122. I went and measured mine and yup, 122! I'm not sure of the effect of too much or too little voltage, maybe someone could write in, but I think any one who owns these multi-wave units would be smart to buy a digitial volt meter at there local Rat-Shack and make sure your voltage is where you think it is. J.D.