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200 amp feed from 200 amp panel?

6K views 17 replies 5 participants last post by  kbsparky 
#1 ·
I have two 200 amp panels servicing my house. Am I permitted to install a 200 amp breaker in a 200 amp panel to feed an outbuilding under construction? Have never heard if a panel may have a breaker fed with the same amperage as the panel feed breaker..
Thanks for your help.
 
#5 ·
Siemens panel with QP breakers. I found a 4-pole 200 Amp QP breaker on-line. Have plenty of space in the panel. I'll see if I can find the lug accessory to avoid buying a redundant breaker.

Also, since this is residential, I believe I can use 2/0 for the two feeds & 1/0 for neutral. Copper. The sub-panel being fed can be grounded with 10 gauge solid to the ground rod at the outbuilding.
Do you agree?

Thanks again - Jack
 
#13 ·
Most residential panels will not accept a branch breaker larger than 100 amps.
Check the specs of your panel to make sure.
Code only allows the use of 2/0 copper to feed the first disconnect.
You will need 3/0 to feed the sub panel 200 amps from the main panel.
Run the forth wire.
 
#15 ·
What is your anticipated neutral load? You can install as small as a #4 neutral on a 200 Amp feeder, depending on its greatest possible unbalanced load.

Your equipment grounding conductor must be at least a #6 copper as well. A #10 ain't going to cut it here.
 
#16 ·
I don't have a large RV but the workshop I'm building can hold one - I think they have 50amp 110V feeds, which is a ridiculous way of using power, but it is what it is. I know they have 30amp 110 feeds. So, I guess it would be a possible 50 amp load on the neutral. If I have to use 3/0 for the subpanel hots I'd use a 2/0 for the neutral.

I've been told to run at least a #6 for the ground down the conduit with the 2 hots & neutral. Can do. I also believe 1 8' copper ground rod at the sub-panel will suffice. Thought I'd use the same AWG as the neutral to connect the ground rod to the panel ground. That may be overkill since my house feed to 2 200 amp panels is 2 runs of 3/0 with 2/0 neutrals. A single ground rod is near this pair of panels with a 1/0 or 2/0 tied to it.

Thanks for your help - can to comment on my wire size thinking? I was going to use 2/0 hots but was told the sub-panel has to be a size larger than the feeds to the main panel(s). Neutral typicaly 1 size smaller..
 
#18 ·
I.... I think they have 50amp 110V feeds, which is a ridiculous way of using power, but it is what it is. I know they have 30amp 110 feeds. So, I guess it would be a possible 50 amp load on the neutral. If I have to use 3/0 for the subpanel hots I'd use a 2/0 for the neutral....
Larger RVs have a 50 Amp 240 Volt feed, using a standard range cord configuration NEMA 14-50.

Using a 2/0 for your panel feeder neutral will be sufficient in any case.


...I've been told to run at least a #6 for the ground down the conduit with the 2 hots & neutral. Can do. I also believe 1 8' copper ground rod at the sub-panel will suffice. Thought I'd use the same AWG as the neutral to connect the ground rod to the panel ground. That may be overkill since my house feed to 2 200 amp panels is 2 runs of 3/0 with 2/0 neutrals. A single ground rod is near this pair of panels with a 1/0 or 2/0 tied to it....
A ground rod is only capable of dissipating a limited amount of juice. Using anything larger than a #6 is a complete waste of resources, since the ground rod can't handle any more. This has been tested and confirmed by independent labs, and the Code recognizes this limitation. :whistling2:
 
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