Does anyone know when the IRC and the NFGC started to prohibit running flex gas lines through cabinetry? I did an inspection recently where this condition was present. I wrote it up as a safety hazard and that a solid gas pipe needed to be installed to the furnace valve assembly that extended through the cabinet for the flex to connect to. The HVAC company that installed the equipment stated that this was allowed when they did the install (approximately 2 years ago), but that they would fix it if I could show them the code. The AHJ was using the 2000 IRC at the time of construction. I know this sounds like I’m trying to enforce code, but the HVAC company is trying to make me look bad with the Realtor. I have called the AHJ and they are little to no help. Thanks
2003 IRC G2422.1.2 Appliance fuel connectors: Connectors shall have an overall length not to exceed 3 feet… Connectors shall not be concealed within, or extended through, walls, floors, partitions, ceilings or appliance housings. A shutoff valve…blah, blah
Flex line is not allowed to pass through the cabinet. I call it no matter how old the home is.
Sorry I do not have a code for you.
I am sure someone will post the applicable code for you. 
Thanks for the replies! I have the 2003 IRC code book and was aware of the 2003 IRC G2422.1.2 Appliance fuel connectors section. What I need is when was this brought into the IRC or NFGC code cycles. Thanks again!
The listing of the appliance connector has never allowed these restricted conditions.
Have them show you otherwise.