Defining Power Codes
So what are power codes exactly? Electrical power codes are guidelines for the installation of electrical wiring and equipment. In the US, the National Electrical Code (NEC), or NFPA 70, is the regional standard of national codes for residential and commercial wiring. Although it is not a federal law, the NEC is adopted by most states and also allows local building departments the ability to add other requirements.
If your current wiring does not meet local codes, chances are that your building department will not require you to change the wiring, as only new work must be up to code. However, if there is old wiring that is unsafe, you are required to change it, and extensive remodeling may be needed.