Do Receptacles in an Attic Need GFCI Protection?
This one trips up experienced hands because the obvious place to look gives the wrong answer. Section 210.8(A) lists the dwelling unit locations where 125 volt receptacles need ground fault circuit interrupter protection: bathrooms, garages and accessory buildings, outdoors, crawl spaces, basements, kitchens, areas with sinks, boathouses, bathtub and shower spaces, laundry areas, and indoor damp or wet locations. An attic is not on that list. So a general purpose receptacle in a finished attic space does not pick up GFCI from 210.8(A).
But most attic receptacles are not general purpose. They exist because there is an air handler or a furnace up there, and that receptacle is required by Section 210.63. That changes the answer.
The 210.63 and 210.8(E) pairing
Section 210.63(B) requires a 125 volt, single phase, 15 or 20 ampere rated receptacle outlet at an accessible location within 25 feet of heating, air conditioning, and refrigeration equipment, for servicing that equipment. In an attic install that receptacle almost always ends up on the platform beside the air handler.
Section 210.8(E) then says GFCI protection shall be provided for the receptacles required by 210.63. There is no dwelling versus commercial split in that sentence and there is no attic exception. If the receptacle is there to serve the equipment, it needs GFCI, full stop. That is why the answer is yes for almost every attic receptacle you will actually encounter, even though the word attic never appears in 210.8.
Practical notes for the install
Feed the attic service receptacle from a dedicated 20 amp circuit rather than tapping the air handler circuit, since 210.63 says the receptacle shall not be connected to the load side of the equipment disconnecting means. A GFCI dead front or a GFCI breaker at the panel both satisfy 210.8(E), and a breaker is often the better choice in an attic because nobody wants to crawl up in July to press a reset button. If you do use a receptacle type device, keep it readily accessible.
Section 210.70(A)(3) is the companion rule people forget: attics, underfloor spaces, utility rooms, and basements containing equipment requiring servicing need at least one lighting outlet with the switch at the usual point of entry. And if the attic is used for storage or contains equipment requiring service, 210.70(A)(3) applies whether or not there is a receptacle. Run the light and the receptacle together on the same trip and the inspection goes cleanly.
One more caution. Nuisance tripping on attic GFCIs is common because condensate pumps and older air handlers leak enough current to trip a 5 milliamp device. That is not a reason to omit protection. It is usually a reason to look at the equipment, since a real leakage path in an attic full of insulation and sheet metal is worth finding.