The question about the RD2624E might be software. Software version 4.2 had the high Vac input at 260 Vac. In 2011 Magnum changed to V5.4 which raised the high Vac input to 275 Vac. For some reason the RD2624E was the only unit with the lower Vac input setting. Once the “High Vac Fault” is registered AC has to be removed before it will reset. So in this case the voltage probably did hit 260 Vac and registered the fault but when it was measured it was lower but would not reset until ac is removed and reapplied to the unit.