Panel Circuit Wiring to Renovated Areas via Attic

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Old 09-16-18, 02:48 PM
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Panel Circuit Wiring to Renovated Areas via Attic

I just upgraded my 1971 house from a 125A Exterior Zinsco(!) panel to a new 200A panel, which feeds most of my 240V items and a 1st floor 100A Interior GE panel (with all *Aluminum* circuits). Iím going to renovate my kitchen and MBA on the 2nd floor and replace most of the electrical wiring with (5) 20A and (3) 15A new copper circuits dropping in from the attic.

I could run all circuits from the Interior panel (see pic of circuits), but donít want to be pushing and pulling bunches of thin Aluminum wires around and Iíd like to take the load off of that panelís main feeder for some peace of mind. Iím currently thinking that it may be easier/safer to run wires from the top of the new Exterior panel along the outside of the brick, up to the soffit and into the attic where I can feed everything down into the kitchen and bath. (see pic) The problem is that the Exterior panel has only one 3Ē opening on top and the meter feeds closely into the bottom, which blocks all the knockouts there.

So, do I deal with De-Rating the tar out of all the conductors running through a single 3Ē conduit, avoid de-rating by punching several (4?) new holes in the top of the panel and run a bunch of small (3/4Ē?) conduits, or do something else entirely? I've done bunches of wiring, but this one has me looking for a better answer, so what do you electrical-folks think?

Thanks!

Bailey
 
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Old 09-16-18, 04:26 PM
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Adding general purpose circuits off the 100 amp panel will not even come close to it's capacity. If that would be easier that would be my first choice.

If you choose to run conduit from the 200 amp panel I would recommend not using cable (you can't use NM-b in conduit outside anyway) and using THHN/THWN individual wires . Install a large junction box in the attic and run the conduit there, then branch off that box with your NM cables. You can then run just two 3/4" conduits for all the circuits you need. Keep the wire counts to 9 or less wires and you will not have to worry about derating.

Running 3" conduit will be a HUGE pain in the butt.
 
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Old 09-16-18, 07:25 PM
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The whole house is running on the one panel now so there is little chance of overloading the subpanel. I would just pull from the inside panel.
 
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Old 09-17-18, 12:18 PM
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Thanks, Ironhand and pcboss for taking the time to offer your advice. I will try to use the interior subpanel for these circuits. It certainly reduces my stress about trying to make that exterior panel work.
 
 

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