What is the law in n.c. about putting out bids on a building?

A little confused by what your asking, but in my community there’s a “Builders Exchange.” You can submit your blueprints and different contractors will bid on them. Members of the builders exchange are licensed and insured.
You can get more information on making sure your contractors are licensed here http://www.nclbgc.net/
Here’s some more info that may help you in NC http://www.nclbgc.net/consinfo_fr.html

Laws don’t, usually, deal with the bidding process, but professional and trade associations (Architects, Engineers, Contractors, etc.) typically have agreement about how the process should be carried out.

Did you have the contract documents (drawings, specifications and form of contract) prepared by professionals; or have you done this yourself?
Will you be managing the bidding process alone or with professional help?
Will you be administering the construction contract by yourself or with professional help?

Are you familiar with construction contract law in your area (eg in most jurisdictions it is not the contractor’s responsibility to ensure their work conforms to building codes; it is the responsibility of the producer of the documents)

Are you fully prepared to proceed with construction once the bids are in? Contractor’s do not take kindly to going through the effort involved in putting a bid together only to find out that they are providing a cost estimating service for free.