Feed to outbuilding..need some help


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Old 11-13-11, 08:33 AM
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Feed to outbuilding..need some help

OK..here's what I've got. 100A sub panel in the attached garage. Its fed from the main house panel from a 100A breaker with H_H_N.
Neutral is bare. Neutral bar is bonded to ground bar. (not sure if this is right to begin with.) I want to run 60A to an outbuilding approx 90ft. Do I use 3 wire H-H-N, or 4 wire H-H-N-G?......OR do I need to rewire the sub in the garage????? Any insight is appreciated.
 
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Old 11-13-11, 09:02 AM
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The garage subpanel should have been fed with 4 conductors. Older codes used to allow 3 wire feeders to panels in detached structures, but not anymore.
 
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Old 11-13-11, 09:04 AM
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Thx...so the solution at this point????? Add a 4th conductor from the main to the sub...and feed the outbuilding with 4 wire?
 
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Old 11-13-11, 09:10 AM
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Just add a ground from the main to the sub in the attached garage. Then, separate the neutrals from the steel cabinet of the sub (the neutral will float) and bond it to the ground.
 
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Old 11-13-11, 09:17 AM
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Can the ground between the main and the sub be bare or insulated??? What guage do I need? Approx 30 ft.
 
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Old 11-13-11, 09:18 AM
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Neutral is bare.
A neutral can NEVER be bare. You need to replace the wiring between the SERVICE (main) panel and the garage panel. You need FOUR conductors, hot, hot, neutral (all insulated) and equipment ground. Any panel other than a SERVICE panel must have the neutral isolated from the enclosure AND a "bonded" (to the enclosure) equipment ground. The equipment ground may be bare.
 
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Old 11-13-11, 10:07 AM
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OK Now Im really confused. Maybe my SERVICE panel is wrong. Please bear with me. SERVICE panel has 200A feed. 2 wires to the main breaker, 1 to the neutral bar. Ground wire from outside ground rod to neutral bar. Neutral bar (on left side of panel) is connected to another bar (which I assume to be ground) via copper plate and it appears all of the above is bonded to the cabinet. Neutrals and grounds are attached to the same bars. Is this correct?
 
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Old 11-13-11, 10:25 AM
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Originally Posted by Furd
A neutral can NEVER be bare.
Never? See Art 338 (2008) particularly B(2) and B(4)(a). The OP's installation would likely be grandfathered in.

Things changed greatly in 2011 code. See 338.10 (B)(2) exception (2011):
"In existing installations, uninsulated conductors shall be permitted as a grounded conductor in accordance with 250.32 and 250.140 where the uninsulated grounded conductor of the cable originates in service equipment and with 225.30 through 225.40."

That said, Frud's post would be the most complete/up to date installation.
 
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Old 11-13-11, 10:27 AM
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Originally Posted by mikkeeh
SERVICE panel has 200A feed. 2 wires to the main breaker, 1 to the neutral bar. Ground wire from outside ground rod to neutral bar. Neutral bar (on left side of panel) is connected to another bar (which I assume to be ground) via copper plate and it appears all of the above is bonded to the cabinet. Neutrals and grounds are attached to the same bars. Is this correct?
That is correct for the SERVICE panel.
 
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Old 11-13-11, 10:39 AM
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ok...so I need to isolate my neutral and my ground in my SUB panel....and feed 4 wire to my outbuilding. right?
 
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Old 11-13-11, 11:18 AM
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Originally Posted by mikkeeh
ok...so I need to isolate my neutral and my ground in my SUB panel....and feed 4 wire to my outbuilding. right?
Almost. Neutral is isolated and ground is bonded. The neutral may have a bonding screw or strap. That needs to be removed. The panel may not have a ground bar. You may need to buy one. There usually are tapped holes in the panel for a ground bar. Any grounds currently on the neutral bar will need to be moved to the ground bar.
 
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Old 11-13-11, 02:13 PM
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As others have said, the correct answer is to run a new 4-wire feed to your garage subpanel, then run a 4-wire feed to your outbuilding. The neutral bar in each panel will be insulated from the pan while the ground bars would be bonded (screwed) to the pan.

On another topic, are you sure you want to pull the 60A feed off your 100A subpanel? Are you sure the 100A feed can handle it? It may be better/easier to just run the 60A feed back to your main panel. Of course, it's up to you - you know the loads on each.
 
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Old 11-18-11, 05:14 PM
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Ok So I was going to use AL 2-2-2-4 URD to feed the outbuilding...but was told I cant run URD inside the house. So...I have to put a junction box on the outside of the house and change wire??? really???
 
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Old 11-18-11, 05:36 PM
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was told I cant run URD inside the house. So...I have to put a junction box on the outside of the house and change wire??? really???
Yes. URD does not have the necessary fire rating for inside use.
 
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Old 11-18-11, 07:13 PM
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Another option would be to use conduit and run individual conductors.
 
 

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