I've got a picnic shelter I'm giving a price on that will include lighting and a few receptacles. The wiring will not be exposed to the direct weather but will be exposed to humidity. Can regular romex be used or do I need to use UF cable ?? thanks..
I don't think NM-B has ever been allowed in damp locations.
I always believed it was because of the kraft paper packing that will wick up water. The only question for the AHJ is how damp is that location?
Location, Damp. Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations...
They are not "THHN" they are just a 90c rated conductor of some kind, since that is all the listing commits to.
As a practical thing we might assume they are THHN, just because of manufacturing expediency but we can't prove it. For that matter you might even assume they are THHN/THWN but you know what assume means.
Who would have thought the covers on NM conduit bodies and the straps for RNC were not made out of the same plastic as the raceway but I had a Carlon rep tell me they don't have to be (in the listing) and in fact, at the time they were not UV protected. I don't know if they ever fixed that.
APPLICATIONS Southwire's Romex SIMpull ® Type NM-B (nonmetallic-sheathed cable) may be used for both exposed and concealed work in normally dry locations at temperatures not to exceed 90°C (with ampacity limited to that for 60°C conductors) as specified in the National Electrical Code 1 . NM-B cable is primarily used in residential wiring as branch circuits for outlets, switches, andvother loads. NM-B cable may be run in air voids of masonry block or tile walls where such walls are not wet or damp locations. Voltage rating for NM-B cable is 600 volts.
I would say no to romex in that location because it would be considered damp. Also your are in a damp location for the cover as well not a wet location subject to pounding rain so a flip up wheater proof cover should be fine.
If it were me, I would spec Type UF, but with work being as tight as it is these days, maybe check with the local inspector so you don't price yourself out of the job if somebody else is bidding it in NM and knows for sure the inspector will allow it. As they say... when in Rome...