I suppose we should describe the type of blower being used. My assumption is that WICruiser is using a salvaged blower assembly from a modern furnace. In this case the blower motor is most likely a direct drive, where the blower wheel is attached directly to the motor shaft. This type of motor is called a permanent split capacitor (PSC) motor, it does not use a separate start capacitor and therefore will not arc in order to drop out a start device. If by chance the blower is a belt drive from an older style of furnace, it could have a separate start capacitor and drop-out switch which would produce a spark upon opening. It is true also that if it is a 3 phase motor as klhansen noted, it will not have a start or run capacitor, if WICruiser has 3 phase in his garage, I want to rent a bay or two. If WICruiser could post a picture of his intended blower, we probably can advise.
