new wiring construction

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  #1  
Old 07-03-12, 07:03 AM
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new wiring construction

This is my set up I am using for a portable building 10x 12 inside dimensions

breaker panel on outside pole 30 amp
wire from breaker pole to inside breaker panel 10/3

inside breaker panel 2 breakers 20 amps

circuit 1 1 15 amp outlet
circuit 2 1 15 amp outlet 1 light fixture (Ceiling fan)

Heaviest load will be on circuit 1 as that will be used for a 5k btu ac window unit.

Question:
Will the 30 amp breaker on the outside pole be sufficient or do I need to run a 40 amp breaker.

I know I could have used 12 gauge wire on the outside line but I wanted to future proof the outside feeder if I ever needed more power.

and yes I probably over engineered this set up.
 
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Old 07-03-12, 08:10 AM
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You could not have used #12 on a 30 amp breaker. Your plan sounds fine and you have capacity for more branch circuits in the subpanel. Just be sure to add an eight foot ground rod, a bonded ground bar and isolate the neutral bar.
 
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Old 07-03-12, 08:45 AM
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I agree with ray
 
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Old 07-03-12, 04:41 PM
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breaker panel on outside pole 30 amp
wire from breaker pole to inside breaker panel 10/3
What type of cable are you using to feed the panel in the building? If this is SO, SOW, SJ or similar type cable you should have used 10-4
 
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Old 07-03-12, 06:05 PM
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breaker panel on outside pole 30 amp
wire from breaker pole to inside breaker panel 10/3
Is this a 120 or 120/240 circuit? If it's 120/240, you need 10/4.
 
  #6  
Old 07-03-12, 06:12 PM
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...inside breaker panel 2 breakers 20 amps
Using 12ga wire no doubt. Just making sure...
 
  #7  
Old 07-03-12, 06:34 PM
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Flexible cords like SO, SJO, SOOW and the like cannot be used in place of permanent wiring.
 
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Old 07-03-12, 06:45 PM
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Flexible cords like SO, SJO, SOOW and the like cannot be used in place of permanent wiring.
This is a portable building, he has to use this.
 
  #9  
Old 07-04-12, 07:07 AM
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will the ground wire and set up circuit on the outside breaker box be sufficient for grounding or do I need to run a second ground bar there is only a total of 25 ft distance (Wire length not straight line distance) from point to point between the two breaker boxes.

When I buried the conduit I placed bricks over the top. I figure if they can't guess from the two ends of plastic conduit and the bricks there is a wire in the ground I want to sit back and watch the fireworks with a beer in my hand laughing when they dig it up.

I ran 12-2 wire on the inside. This particular building will never be upgraded. IF it is I will have to install a larger box as I only have a 2 breaker panel box inside It is for a small retail shop. the future proofing is in case I ever end up moving the building from the property and they put another building in.
 
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Old 07-04-12, 07:31 AM
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How deep is the conduit" What kind of wire did you run? THWN?

or do I need to run a second ground bar there is only a total of 25 ft distance (Wire length not straight line distance)
Wire length is not a factor. The subpanel must have an isolated neutral bar and a bonded ground bar. Since ground bars are not usually included you would probably need one. In addition you need a ground rod driven eight feet in the ground. Both the EGC* from the main panel and the GEC* from the ground rod go to the ground bar. The GEC can be as small as #8 but if you make it #6 it will not need to be in conduit.

*Definitions
EGC= Equipment grounding conductor, the green or bare wire from the pole panel.
GEC= Grounding electrode conductor, the wire from your ground rod
 

Last edited by ray2047; 07-05-12 at 05:32 PM.
  #11  
Old 07-04-12, 11:06 AM
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The GEC can be as small as #10 but if you make it #6
The minimum size a GEC can be is a #8.
 
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Old 07-05-12, 04:12 PM
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Both the EGC* from the main panel and the GEC* from the ground rod go to the neutral bar.
Ummm...Ray, I think you meant ground bar.
 
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Old 07-05-12, 04:26 PM
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CJ, thanks for the catch. I changed Rays post.
 
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