Above ground (outdoor) UF-B cable and Conduit

Question

We have a UF-B (12/2) cable run in PVC conduit above ground from panel onto a wall on a side of the house up to a point (fence comes then). Then the conduit goes underground and 90-degree and emerges from the ground under the deck (upto about 2 feet above ground in a conduit).

Then the cable runs without the conduit (under the deck) to a GFCI. Then, from GFCI (goes under the deck - above ground ~2 feet) to another outlet Then (goes under the deck - above ground ~2 feet) to a switch which controls the fan. Switch is about 6 feet from the ground and about 3 feet from the deck floor).

I was thinking to (re)run the UF-B cable that runs from the switch to the fan in a PVC conduit (mainly from the optics point of view. Also, at some time this year, I am planning to run the exposed cable under the deck in a PVC conduit.)

I went to Lowe's and was looking for fittings and asked for help. The rep was quite helpful but they asked if I have a gray cable that I am planning to put in the conduit (which is what it is - UF-B). They said that it's against national electric code to run gray cable in a conduit above ground and insurance company might not approve of that in case of an issue.

Could someone please help me with the codes for UF-B cable?

I appreciate your help with this.

Thank you.

Answer 1

As a practical consideration it should be avoided because it's a PITA to pull through PVC, you must use larger conduit than expected, strange securing rules apply, but not completely prohibited.

You must follow conduit fill rules, Chapter 9 Table 8 Note (9) says you must treat a cable as a round single conductor of the large dimension of the cable. One brand of UF specs the large dimension of 12/2 as 0.620", requiring 3/4" for a single cable.

Section 312.5 says cables entering a cabinet (including a panelboard cabinet) must be secured to the cabinet, unless you met conditions which allow through conduit 18" to 10' in length, longer conduit than that that require securing by (UL) Listed method which may or may not exist.

But Section 340 deals with UF, 340.10(4) permits use as NM, when installed per the NM Section, Section 334.

Nothing in 334 says you can't rum in conduit, and specifically says in 334.15(B) that where exposed to physical damage you must protect with one of types listed, including schedule 80 pvc.