Can an electrical panel be behind a locked door in North Carolina
If you own the building, and provide &quot;continuous building management supervision&quot;. Then yes, the panel can be locked up. Otherwise, no. Tenants need to have access to their panels.
Well, technically... The door can be locked, but the tenants must have a key.

National Electrical Code 2014
Chapter 2 Wiring and Protection
Article 240 Overcurrent Protection
240.24 Location in or on Premises.
(B) Occupancy. Each occupant shall have ready access to all overcurrent devices protecting the conductors supplying that occupancy, unless otherwise permitted in 240.24(B)(1) and (B)(2).
(1) Service and Feeder Overcurrent Devices. Where electric service and electrical maintenance are provided by the building management and where these are under continuous building management supervision, the service overcurrent devices and feeder overcurrent devices supplying more than one occupancy shall be permitted to be accessible only to authorized management personnel in the following:
(1) Multiple-occupancy buildings
(2) Guest rooms or guest suites.
(2) Branch-Circuit Overcurrent Devices. Where electric service and electrical maintenance are provided by the building management and where these are under continuous building management supervision, the branch-circuit overcurrent devices supplying any guest rooms or guest suites without permanent provisions for cooking shall be permitted to be accessible only to authorized management personnel.