shared raceway, THHN2 run through 24" pass through from MSP beside existing Romex

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sarahL

Member
Location
WA
Occupation
Contractor, solar QM
I am working to run 2 new circuits (each 60A using 3-#6 THHN-2 and 1-#10 EGC) through a 24" pass through from the main panel on exterior to a 1.25" PVC conduit in the basement). The circuits where planned to run from the MSP down through a 2" PVC conduit to pass through to the basement where they would immediately enter the PVC (to avoid conduit on the outside of the home as homeowner desires). That 2" conduit already houses 6 NMB/Romex circuits (4 #12/2 and 2 #10/3). There is enough room per NEC conduit fill calculations, but our inspector believes that the new circuits must be run complete from the start to finish and cannot be contained in this 24" pass through with existing circuits.

I believe that the 24" section of conduit from the MSP to the basement should not be a problem, especially because the short run is PVC, not metal.

2017 NEC 300.18 RaceWay Installation , exception states: "short sections of raceway used to contain conductors or cable assemblies for protection from physical damage shall not be required to be installed complete between outlet, junction, or splicing points".

I also reviewed NEC 300.20:- I believe this may have been a concern of inspector , but it applies to metallic raceways. Induced Currents in Ferrous Metal Enclosures or Ferrous Metal Raceways: (A) Conductors Grouped Together. Where conductors carrying alternating current are installed in ferrous metal enclosures or ferrous metal raceways, they shall be arranged so as to avoid heating the surrounding ferrous metal by induction. To accomplish this, all phase conductors and, where used, the grounded conductor and all equipment grounding conductors shall be grouped together.).

Please let me know your thoughts- is this acceptable or do we need to run a separate conduit on the outside of the home?
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Welcome to the forum.

The problem I see is that the individual conductors must be in a raceway from enclosure to enclosure.
 

sarahL

Member
Location
WA
Occupation
Contractor, solar QM
The pass through is a 2" PVC that runs down from the bottom of the exterior MSP to an LB that penetrates into the home. It leads into the basement where the NMB spread out to feed lighting and outlet circuits in the basement. There is no conduit on those NMB.
I was hoping the exception in 300.18 would allow me to run these 2 new THHN2 circuits inside the PVC with the other NMB wires, from the breakers in the MSP to then enter into a PVC in the basement.
I cannot find in the NEC where it specifically states that the circuits have to be in a dedicated conduit... I think you are right in general, I am just looking for simplifying the situation where it seems there is minimal to no risk.
Thanks again for your feedback!
 

sarahL

Member
Location
WA
Occupation
Contractor, solar QM
Dennis I am allowed to do the work as a homeowner as permitted where I live and I have a permit I am working under for this job. I have worked in the solar industry for 10 years, and am NABCEP certified so I am pretty comfortable with code, etc.
 

tom baker

First Chief Moderator
Staff member
Seems like a DIY project. I will lock this and we mods can sort this out by. In WA the solar installer must be a certified electrician working for a licensed electrical contractor.
 
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