[VAC] Re: Is 104 volts enough?

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx>]

Dan, you need to find an outlet closer to the service panel or wired
with larger wire. Starting out at 108, your cord isn't going to make so
much difference, though it will help. When you are dropping to 108 at
the outlet it makes me think you are plugged into a receptacle wired
with 14 gauge which isn't adequate to handle your trailer load with A/C.
It would be worth using your long 10 gauge cord to search about the
premises for an outlet closer to the main entrance panel with better
voltage regulation. You 10 gauge cord has larger conductors than any 120
volt building outlet wiring. Ideally you might find it worth the bother
to hire an electrician to install a RV 30 amp receptacle and circuit
with 10 gauge conductors. Everything in the trailer will work better
then.

104 is on the edge. For the induction motors it means the current is
increased by the 117/104 ratio and the winding heat from resistive
losses by the square of that... And that heat increase is what
eventually takes the insulation out and causes failure. Motor (and
transformer) insulation failure is considered to be accumulative of heat
events. Short periods of overheating (that aren't hot enough to cause
instant failure) accumulate damage to the paper basic to the insulation.
When the paper disintegrates from that accumulated damage, then the
enameled wire is more free to vibrate against the bare laminations and
wear through the enamel. Once the enamel is breached the winding is
wrecked.

Gerald J.