There are many facets to the electrical industry. There are as many or more versions of code pertaining to signage. We are very familiar with a variety of applications used by local municipalities. Below you will find information and links pertaining to local code requirements. You should always verify with your local inspectors for their specific requirements.
Washington State Department of Labor and Industries http://www.lni.wa.gov/TradesLicensing/Electrical/default.asp
King County Code http://www.kingcounty.gov/council/legislation/kc_code.aspx
City of Seattle Department of Planning and Development http://www.seattle.gov/dpd/codes/default.asp#general