Old panel to new panel to wire trough via 2" PVC

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Old 05-15-20, 04:20 PM
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Old panel to new panel to wire trough via 2" PVC

Code compliance question; can I do this in my basement?
  1. Add additional basement breaker panel alongside my exiting one. (No more breaker room on the existing panel.)
  2. Jump old panel to new panel with what ga wire? Old panel: 100 amp. New panel already has 100 amp mains breaker. Breaker size on old panel?
  3. Build 2" PVC out of new panel to a rafter mounted 6" x 6" x 36" wiring trough. Why? There's no room on right side of new panel for easy new Romex circuits installation.
  4. Run bare copper ground (4 or 6 ga?) from new panel to ground bus terminal strip in wire trough via the 2" PVC. Terminate all grounds in trough to ground bus.
  5. Run all new circuits from wire trough to new panel through the 2" PVC using 12 ga. wire (black/white) pairs.

SEE ATTACHED PICTORIAL
 
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Old 05-15-20, 06:47 PM
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Build 2" PVC out of new panel to a rafter mounted 6" x 6" x 36" wiring trough. Why? There's no room on right side of new panel for easy new Romex circuits installation.
Why not just locate the new subpanel somewhere else where there is plenty of room to add new circuits to it and avoid the trough and 2" conduit? OR......just replace the existing panel with a panel that has more circuits?

I generally always try to avoid creating a Rube Goldberg.
 
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Old 05-15-20, 08:15 PM
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The new panel is already mounted next to the old panel with a temp jum from the old to the new.
The wire trough was installed some time ago.
The current installation is a Rube Goldberg. (Rube was well intentioned, but his work could kill you. You've been there.)
I need to finish up this project -the right way.
I don't want an inspector to say, rip this out before I sell my house.
I just want to meet/exceed Code.
I also do VERY neat work.
Many thanks!
 
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Old 05-15-20, 08:35 PM
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If the 2" conduit is more than 24" then you have to take derating into account and then you are pretty much limited to 9 current-carrying conductors. If it is less than 24" it is considered a nipple and you can fill the pipe to 60%.

Breaker size in the main panel? It depends on what size wire you want to use or how many amps you want available to the sub-panel. I would recommend three #6 wires, one #10 ground, and a 60 amp breaker.

Ground wire to the gutter will depend on the largest conductor in the pipe. If it is #12 then you only need to use a #12 for the ground.
 
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Old 05-15-20, 08:51 PM
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MANY thanks for your response.
Ok with the breaker/wire size.
However, the derate issue.might kill the wire trough idea. I was hoping to accommodate more circuits in the 2".
 
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Old 05-16-20, 05:54 AM
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Hi, no need for Schedule 80 PVC , 40 is fine, how many Romex’s are you moving?
Geo
 
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Old 05-16-20, 06:19 AM
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the derate issue.might kill the wire trough idea. I was hoping to accommodate more circuits in the 2".
You can use larger wires to offset the derating requirements. If you keep the current-carrying conductors to no more then 40, and you use #10 wires, you would still be able to use a 20 amp breaker. You can put 62 THHN wires in a 2" Sch 40 pipe at 40% fill or 54 in a 2" Sch 80.
 
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Old 05-16-20, 07:04 AM
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I would skip the trough and just bring the cables into the panel.
 
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Old 05-16-20, 02:57 PM
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The Group Moderator said the 2" conduit over 24" in length can only accommodate 9 conductors.
 
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Old 05-16-20, 03:02 PM
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Moving and adding.
The derating in 2" PVC is now my concern.
Still would like to know how many conductors in over 24" is allowed.
 
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Old 05-16-20, 04:19 PM
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Still would like to know how many conductors in over 24" is allowed.
See my post #8
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Old 05-18-20, 11:58 AM
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It's typical to solve your problem with separate NM-B cables from the panel to a junction box in the ceiling (accessible), then out to the circuits. It happens when the cables aren't long enough.

It could be a couple double-gang plastic new work boxes, a couple 4x4 metal boxes, or a larger 6x6 or 8x8 box if you'd rather. All are rather usual to see in a setup like this.

Due to the derating requirements, making it look all neat with conduit and trough isn't usually done in residential settings.
 
 

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