Abstract: A trip unit is provided with non-volatile memory, such as EEPROM (Electrically Erasable Programmable Read Only Memory) or Flash memory, for storing the firmware, including initializing parameters, boot code, and operational parameters. This configuration enables one to change the trip unit's firmware after it is manufactured. The present invention provides thus increased functionality to trip units by enabling upgrades and servicing of the trip unit by downloading replacement firmware to it. This would include remotely downloading firmware when the electronic trip unit is connected to a host controller, such as a multi-purpose computer either directly, over the telephone lines, LAN or any other suitable connection such as the Internet.