Using THWN inside conduit

[stardog]

Our electrical panel box is installed on the exterior brick veneer wall of our house. I am having our electrician add an extra 20 amp branch circuit to the panel to feed 3 new receptacles in the kitchen area, the first of which will be GFCI-AFI protected, which in turn will protect the other two downstream.

The least labor intensive way to route the new cable from the panel box into the unfinished attic is to run it directly from the panel box into the soffit above the box (a distance of 11 inches), then into the unfinished attic. I realize Romex cannot be placed in conduit, even for this short 11 inch exposed distance. Therefore, I am considering using 12 AWG THWN for the connections inside the box, then run the THWN via conduit (either PVC or EMT) into the attic. Once inside the attic, the THWN and Romex will be spliced inside a junction box, then the Romex will be run across the rafters to the new outlets.

I have two questions about this:

1. Is using THWN for the connections inside the panel box, then splicing with Romex once inside the attic space, an accepted and code approved practice in this unique type of situation, where the panel box is located outside. If not, then what are possible options in cases like this?

2. If splicing is acceptable, would the splice itself have any negative effect on the proper functioning of the GFCI-AFI that will be installed on this circuit? If the splicing degrades the circuit in any way, shape, or form, then I presume nuisance tripping would be a regular occurance.

Any professional input on these two questions is appreciated so I can plan ahead.

 

[Stuff]

1 - Plan is fine. Try to avoid any connections coming out of the top of the panel as easy to let water in. Lazy option is to use UF cable the whole way without conduit.
2 - Proper splicing has no effect on GFCI/AFCI

With a new circuit the AFCI normally has to be done by a breaker in the panel.
Note that you can't run over the rafters within 6' of the access hole.

 

[Sponsor]

 

[stardog]

1 - Plan is fine. Try to avoid any connections coming out of the top of the panel as easy to let water in. Lazy option is to use UF cable the whole way without conduit.
2 - Proper splicing has no effect on GFCI/AFCI

With a new circuit the AFCI normally has to be done by a breaker in the panel.
Note that you can't run over the rafters within 6' of the access hole.

Thanks. I forgot about the required upgrading when making modifications, so yes, it will be 20 amp AFCI breaker with a standard GFCI at the first receptacle. And since I'll be using THWN inside conduit, the conduit will be run from the side of the panel to avoid water seeping in. It will be a clear run across the open attic, and well away from the pulldown stair opening.

Appreciate the quick reply.

 

[Jadnashua]

Make it simpler...there are combined AFCI/GFCI breakers.

You may need a waterproof box outside...I'm not positive about that, though.

 

[Bcarlson78248]

I believe you may be confused about NM/Romex cable and conduit.

Unless you are working under a specific local code requirement from an inspector, there is no reason you cannot install NM cable (Romex) inside conduit, especially if its only for a foot or two. Its a PIA to pull jacketed NM through corners and bends, but there is no national electrical code section that says it cannot be in conduit. You just can't exceed the file capacity of the conduit, which would be hard to do with NM because its so bulky.

Bruce

 

[Stuff]

Conduit installed outdoors is considered a damp or wet location so NM is not allowed with its paper construction.

 

[Bcarlson78248]

You're right, I was focused on the NM in conduit question and didn't address the wet/damp location. It would have to be a wet location rated cable assembly (UF, etc.).

AFAIK, UF could also be run in conduit for this short run from the panel up to the soffit, and then continued on into the house to complete the circuit. This would eliminate the need to transition from THWN to another type of wire inside.

Bruce