I must add that it is an important step to go beyond just knowing electrical codes for your area, we should also be exploring what your state and local law also has in it that pertains to your work, not knowing the law can result in a lot of trouble and unnecessary cost for your customers and you, and protects you from doing things your not allowed to do or being required to do things that are really not required.
depending on hearsay can be a road to disaster.
With the Internet, almost all state laws can be researched right from our homes, local law is required to be published either on the Internet or at your local public library's, or can be found by calling the local city/county and they have to provide where you can look it up. but it is always best to be in the know, when dealing with law.