Q The National Electric Code mandates the use of GFCIs in high-risk areas of all new residences. Do you have any statistics regarding how many U.S. houses were built prior to the NEC mandate that are without GFCI protection? If you have this information could you also please tell me the source? Or can you give me some suggestions on whom I may contact to get this info?
A I do not know of any source for the information you are looking for. I suspect that such information would be very difficult to compile. Over the years GFCI requirements have been expanded in most three-year code revisions.
In addition, some older homes have been upgraded but not all of these were brought up to current Code requirements. Some, such as mine, even exceed NEC requirements and have GFCI protection on receptacles that are not required to be GFCI protected. Another factor is that some homeowners do not understand GFCI protection and consider it to be an unneeded bother. In some homes the GFCIs have been removed and replaced with standard devices.