Disputes over maintenance, repair and replacement responsibilities are common in community associations and a well drafted declaration or amendment to the declaration can help prevent disputes over who (owner or association) is responsible for a specific item of maintenance.
Regarding how to interpret your existing condominium documents, the unit boundaries will be defined within the declaration and sometimes within the site plan. Any item/component including electrical wires and plumbing located within the unit boundaries is the unit owner’s responsibility to maintain, repair and replace (unless the declaration states otherwise). In contrast, any item/component located outside the unit boundaries is a common element (or a limited common element) and the association is responsible to maintain, repair and replace the common elements unless a given item is identified in the declaration as a limited common element (benefiting the subject owner) and also identified as being the maintenance, repair and replacement responsibility of the unit owner.