“Voting power” means the power to vote for the election of directors at the time any determination of voting power is made and does not include the right to vote upon the happening of some condition or event which has not yet occurred. In any case where different classes of memberships are entitled to vote as separate classes for different members of the board, the determination of percentage of voting power shall be made on the basis of the percentage of the total number of authorized directors which the memberships in question (whether of one or more classes) have the power to elect in an election at which all memberships then entitled to vote for the election of any directors are voted.