A. Prior to a substantial change in use (for both principal and accessory uses), a new certificate of occupancy shall be obtained. If the existing use or the proposed new use is one which requires a special permit and/or site plan approval (as set forth in § 390-4.2: Use Regulation Schedule.), a new special permit and/or site plan approval shall be obtained prior to the issuance of a certificate of occupancy. 
B. A substantial change of use occurs when: 

(1) The change is from one principal use category to another (i.e., use classifications that are on different lines in § 390-4.2: Use Regulation Schedule.);
(2) The existing use of a lot is a combination of several different principal uses, such as different retail establishments, offices or restaurants within one building, and
the changes alters the off-street parking requirements for the overall use of the lot;
(3) The operating characteristics of the new use differ substantially from that of the use which it replaces because there are adverse impacts on nearby properties, or the capacity of public services or facilities is not adequate to accommodate the new use;
(4) In the case where a special permit or variance is in effect, the change would result in exceeding any conditions included in the special permit or variance, even if the preceding use and the new use are on the same line in § 390-4.2: Use Regulation Schedule.

C. A change in ownership or management of an establishment conducted as a principal use, and not resulting in any of the changes listed above, is not considered a substantial change in use.