I have a panel at a customers home that has a burnt bus so I recommended replacement of the panel along with the breakers that are damaged. Existing panel is 7 years old. If I purchased the exact panel and replaced just the internal parts such as the bus along with the main breaker assembly, would that void the UL listing of the panel?
Short answer yes.
So the following does not apply:
110.3 Examination, Identification, Installation, and Use
of Equipment.
(B) Installation and Use. Listed or labeled equipment
shall be installed and used in accordance with any instructions
included in the listing or labeling.
IMHO you now go to:
110.3 Examination, Identification, Installation, and Use
of Equipment.
(A) Examination. In judging equipment,
considerations
such as the following shall be evaluated: .......
90.4
...The authority having jurisdiction for
enforcement of the Code has the responsibility for making
interpretations of the rules, for deciding on the approval of
equipment and materials, and for granting the special permission
contemplated in a number of the rules. .....