To determine the maximum allowable overcurrent protection for the feeder conductor, we need to apply the tap conductor rules in the NEC (National Electrical Code). According to NEC 240.4, the overcurrent protection for conductors and equipment must not exceed their ampacity, except for certain specific conditions including tap conductors. NEC 240.21 specifies the requirements for overcurrent protection for tap conductors. It states that the overcurrent protection for a tap conductor must not exceed the ampacity of the tap conductor, and it must also comply with the rules for the type of overcurrent protection device used. NEC Table 310.16 provides the ampacity for conductors based on their size, type, and temperature rating. For a tap conductor that is 30 amperes, we can look up the ampacity for a 10 AWG copper conductor with a 90°C temperature rating. According to Table 310.16, the ampacity for a 10 AWG copper conductor with a 90°C temperature rating is 40 amperes. Since the tap conductor ampacity of 30 amperes is less than the ampacity of a 10 AWG copper conductor with a 90°C temperature rating of 40 amperes, the maximum allowable overcurrent protection for the feeder conductor would be 30 amperes.