Using a main breaker panel as a sub panel

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Old 04-29-16, 03:04 PM
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Using a main breaker panel as a sub panel

I'm putting a sub panel in my pole barn, that is a Homeline 200 amp main breaker panel. I am using this panel because I had it, and it came with ten 20 amp breakers. I'm feeding it from the house with an 80 amp breaker, and 1/0 aluminum. My plan was to back feed an 80 amp breaker at the sub panel. I bought 2 different Homeline breaker retaining kits, and neither fit correctly. MY thought is that these retaining kits are for Main Lug Only Panels? Then I thought, Could I just run the 1/0 to the main breaker, and forget the whole back feed scenario? Can the 200 amp main be considered a master shut off? I don't want to buy a panel if I don't have to. Thanks. John.
 
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Old 04-29-16, 03:17 PM
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Go ahead and use the subpanel as you have planned. It will be a bit of overkill in terms of how much money you spent for it.

Normally the first panel in an outbuilding is fed using either a top breaker or top lugs.

So long as the supra-panel has the proper sized breakers for the feed wire size (side breaker set for your outbuilding power feed) you can feed the subpanel using its existing top 200 amp breaker but it would be a good idea to label that breaker with the feeding amperage.

Be sure to undo the bonding strap or green grounding screw from the neutral bus bar (has plastic brackets holding it in place) to the panel back (or to a ground bus bar) in the panel being used as a subpanel.
 
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Old 04-29-16, 03:22 PM
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Could I just run the 1/0 to the main breaker, and forget the whole back feed scenario?
Yes, that is the way it is normally done.
Can the 200 amp main be considered a master shut off?
Yes, the main breaker is just a disconnect. The way you are doing it is the way we would normally advise you to do it even if you had to buy a panel (though perhaps a smaller panel to save a bit on cost if buying). You will need to buy and add a ground bar to it and if the neutral bar is bonded you will need to remove the bond. You will need a four wire feed to the panel and at least one ground rod at the barn connected to the ground bar with #6 copper.
 
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Old 04-29-16, 04:13 PM
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Just make sure the lugs will accept the #1/0.
 
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Old 04-29-16, 07:11 PM
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Why are you using 1/0 Al for 80A? Do you have a long run? #2 Al is all you need for 80A unless the distance is an issue because of voltage drop.
 
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Old 04-29-16, 08:19 PM
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Just a quick terminology note there is really no such thing as a subpanel. The term is never used in the NEC. It is simply an unofficial term for any breaker box that does not contain the first over current protection device. How the box is used not how it is made determines if it is a subpanel or not.
 
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Old 04-29-16, 08:59 PM
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The run is 230'................
 
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