An electrical unit with modular hardware structure in which more complex and unsafe portions of the device are restricted for access by a qualified electrician only, whereas safe areas are made accessible to a non-electrician user, such as a homeowner or a low expertise technician, to help diagnose issues and/or upgrade the functionality of the device without requiring the presence of a high expertise technician/electrician. The unit may include the ability to add new communication interfaces in a modular manner, preferably by a non-electrician user. Protection domains are created by designing the electrical unit to include an easier level of physical access, open to the homeowner or a low expertise technician. This area would support the modular upgrade interfaces for communication and/or diagnostic interfaces for troubleshooting. A restricted area of access may be used to shield the high voltage wiring as well as wired industrial communication interfaces from the homeowner.