If you read article 300.4 I beleive you would be fine with UF under the deck. #1 the UF is rated for exposure and #2 the deck with limited access affords the required protection. Even if the deck was exposed under, as long as the wire is bored through the joist or stapled to the side of the joist, you meet 300.4. This is my opinion and if I'm wrong someone will correct me.
Re: Question?#12686 08/15/0201:39 AM08/15/0201:39 AM
Joe, you're right as usual, however, I'm sure the other joe meant the dual rated THHN THWN, 'cuz I've seen no THHN that isn't rated THWN, and calling it the wrong thing doesn't make it lose its wet rating, correct?
The stuff I use says the following, maybe y'all use different stuff.
"GCC -W 12AWG VW-1 TYPE THHN OR THWN OR MTW (UL) 600 VOLTS GASOLINE AND OIL RESISTANT 11 OR AMW"
Could we just call it THHN and assume we're all talking about the same thing?
BTW, if I ask my supplier for THWN, they usually say "We don't carry that, but we can order it", then I'll say "Oh, just give me THHN instead."
I get exactly what I wanted in the first place!
-Virgil Residential/Commercial Inspector 5 Star Inspections Member IAEI
Yes I should have clarified THHN/THWN. i've always seen it marked together. It would be at the installers discrection to determine damp or wet location and then provide the right materials for the job. I must say that most deck wiring that I've done lately would be visible from below. A house on a hill with a ground floor entrance and a second floor deck, hence my willingness to use PVC. My thoughts of UF and standard steel staples, that might one day rust out and allow the cable to fall away from the structure was my reason to use PVC, two hole straps and stainless steel screws. Alot of my work comes from referrals and to have a potental customer see a professional job several years down the road, would encourage me to go the extra mile so to speak and bid the job as I have done. In a ground level deck situation where traffic disturbing the wire may not be an issue, and economy is a concern the UF if attached with the two hole plastic straps and stainless screws should do fine. Sometimes a code installation may be acheived through several avenues, mine may seem overkill to most but short of RMC I feel comfortable with it.