Non-Metallic NM-B in conduit in a porch

[jrc0109]

If I remember correctly, NM-B can be run through conduit in normally dry locations. But it can't be in conduit in wet locations. The code considers the inside of a raceway in wet locations as a "wet location". Has anything changed? The application would be coming through an exterior wall and running down the wall in an enclosed porch to a light switch in a metal box. If it is not allowed, can a function box be installed in the attic and connect the NM to XHHW-2 wires into the conduit down to the switch?

 

[suemarkp]

I don't see an enclosed porch as a wet area, but the AHJ may consider it a damp area which doesn't work for NM-B either. Best thing is just use UF cable from wherever this circuit leg will originate, or you can use a junction box inside and run individual THWN conductors in a raceway to the switch. With the rules for switches requiring neutrals, the junction box may actually be better because you don't need to pull one in that case. Otherwise, it would be two UF xx-2 cables or a xx-3 UF cable.

 

[jrc0109]

Thank you very much for your answer. Regarding the neutral, does the code now require new switch installations to have a neutral wire? is that because of smart switches?

 

[suemarkp]

Yes, smart switches, occupancy sensors, and dimmers that were either using the load or the ground as a conductor to run the internal electronics.

See 404.2(C) for details.

 

[jrc0109]

Thanks again

 

[Jraef]

Yes, smart switches, occupancy sensors, and dimmers that were either using the load or the ground as a conductor to run the internal electronics.

See 404.2(C) for details.

I just went through this exercise... You have to read ALL of the text in 404.2.C...

The grounded circuit conductor for the controlled lighting circuit shall be installed at the location where switches control lighting loads that are supplied by a grounded general-purpose branch circuit serving bathrooms, hallways, stairways, or rooms suitable for human habitation or occupancy as defined in the applicable building code.

In my case, I argued that the porch was not considered "suitable for human habitation", meaning occupancy sensors were not required now or in the future, so the switch loop didn't need a neutral. I prevailed.

 

[cadpoint]

I use to habitation the screened in porch in the summer... Dawn patrol for beach trips...Dude