[Oldhouse1940s]

Breaker box mounted on outside wall of house, Romex incoming from house circuits via crawspace or attic. Is is Code-compliant to have a short piece of conduit (2-3 feet) running from the crawlspace or attic to the breaker box and just continue the Romex through that conduit into the box?

Or do you have to create a separate junction box in the crawlspace or attic, end the Romex there and do THHN from the junction box (through short conduit) into the breaker box?

(California)

Thanks!

 

[dcwired]

No knowledge of your jurisdiction, but I have passed inspections many times sleeving the Romex.
If you take the code to the letter, it says inside a conduit is considered a wet location and therefore the wire needs to be wet location rated. This is an inspector's call.

 

[Jim Port]

NM is not for use outside, even if sleeved in conduit.

NM can be sleeved in conduit in a dry area.

 

[Oldhouse1940s]

Thank you both. If the Romex can't be outdoors even sleeved in conduit, I guess that means it also couldn't be brought into a junction box that's mounted on the outside wall of the house, even if entry into the J-box is directly behind it, into the back of the box from crawlspace or attic, right? The Romex would be coming into the box, therefore outdoors, even though it terminated there. So the J-box would have to be inside the crawlspace or attic, and the conduit from there to the breaker box would contain only the TWWN.

 

[Jim Port]

NM can enter the back of the box. The inside of the box is not a wet area.

 

[seharper]

Also, the conduit would have to be less than 24" long, or be limited to 3 circuits. (4 if all are 15-20A). So one giant conduit to rule them all only works if it's short.

 

[Oldhouse1940s]

Also, the conduit would have to be less than 24" long, or be limited to 3 circuits. (4 if all are 15-20A). So one giant conduit to rule them all only works if it's short.

Thank you. I think that rule about the 24" is what I was vaguely remembering, but couldn't find it. Where is that in the Code?

 

[seharper]

@Oldhouse1940s 310.15(B)(3)(a) or Chapter 9 table 1, I don't quite recall.

"3 circuits, or 4 circuits if 15-20A" is a complex derivation from

• the above two
• 310.15(B)(16)
• 240.4(D)
• 334.80

 

[Oldhouse1940s]

@Oldhouse1940s 310.15(B)(3)(a) or Chapter 9 table 1, I don't quite recall.

"3 circuits, or 4 circuits if 15-20A" is a complex derivation from

• the above two
• 310.15(B)(16)
• 240.4(D)
• 334.80

Thanks very much. I was hunting around in the Code and also came up with Chapter 9 note 4: "Where conduit or tubing nipples having a maximum length not to exceed 600 mm (24 in.) are installed between boxes, cabinets, and similar enclosures, the nipples shall be permitted to be filled to 60 percent of their total cross-sectional area, and 310.15(B)(3)(a) adjustment factors need not apply to this condition."