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Old 03-28-2012, 12:07 PM   #1
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underground electrical cable


I am running an underground cabe from my house to an outbuilding, I need to know what to buy and any code that applies, I live in Ga. I am taping off an existing 240 line and split it at the out building into two 120 lines, one for lights (2) and one for outlets (5). I have two 30 amp breakers at the out building.. I am taping off a 100 anp breaker at my AC unit.

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Old 03-28-2012, 12:13 PM   #2
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What part of GA?

Explain how you are tapping off the ac circuit.
How are the breakers at the outbuilding being fed now?

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Old 03-28-2012, 12:26 PM   #3
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The air conditioner does not have a neutral and cannot be used for 120 loads like receptacles and lights.
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Old 03-28-2012, 12:31 PM   #4
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I don't think you can tap your AC line for this. If you can then you need to use 100 amp rated cable since the breaker in the main panel is 100 amps. then install a 100 amp sub panel in the out building and run your circuits from there.

That must some huge AC if it uses 100 amps.
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Old 03-28-2012, 12:33 PM   #5
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I am taping off the breaker box just prior to the AC unit which is 240, with a 65 amp breaker, I live in south Ga, Colquitt county!
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Old 03-28-2012, 12:36 PM   #6
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I am running an underground cabe from my house to an outbuilding, I need to know what to buy and any code that applies, I live in Ga. I am taping off an existing 240 line and split it at the out building into two 120 lines, one for lights (2) and one for outlets (5). I have two 30 amp breakers at the out building.. I am taping off a 100 anp breaker at my AC unit.
You cannot run standard lights and receptacles off of 30A breakers. As has already been stated, the line to an AC unit will not have a neutral so it cannot be used for 120V loads.
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Old 03-29-2012, 07:58 AM   #7
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I am taping off of a 240V line and going to a breaker box with two 30amp breakers, I tap off one leg of 240 to get 120 line, which runs lights just fine!
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Old 03-29-2012, 08:03 AM   #8
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I am taping off of a 240V line and going to a breaker box with two 30amp breakers, I tap off one leg of 240 to get 120 line, which runs lights just fine!
So this means you are using the grounding conductor as a neutral? If so you need to disconnect it now before someone gets hurt or worse. The lights cannot be protected by a 30 amp breaker either.
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Old 03-29-2012, 08:03 AM   #9
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If the AC doesn't have a neutral, you can't get 120V at the outbuilding...you will only have 240V. And before you ask...the ground (bare) cannot be used as the neutral for a number of reasons.
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Old 03-29-2012, 08:50 AM   #10
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There seems to be some confusement as to my hook up, I am taping a 240 line, with a 10-2 wire with ground. I have a groundwire and a white and a black line. I run this to a box in out building and connect the two legs. I tape one leg of the 240 and and then the 30amp fuse breaker to get the 120 line. Am I missing something?
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Old 03-29-2012, 08:53 AM   #11
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The ac unit does not come into play!!!
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Old 03-29-2012, 08:56 AM   #12
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The black and white are both 120 volts to ground. The white is not a neutral. Using the bare ground as a return path for your current could have deadly consequences.

You cannot safely do what you are trying to do.
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Old 03-29-2012, 08:57 AM   #13
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Am I missing something?
Most definitely! You cannot feed a subpanel with 10-2 wire. You would need 10-3 with a ground. If you use 10-2 and wire it for 240V, you will not have 120V without the neutral.
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Old 03-29-2012, 08:58 AM   #14
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Let clearify something. First the lines coming from my house is (2) Two 120 lines. thay go to a box near the AC unit. I tap off one leg of each of these two line to get the 240 to out building and then seperate them back to the (2) 120 lines in the out building. the circuit breaker in my house the origin of the two 120 lines is (2) 100amp breakers. each with a 120 line. If this is not the way it should be , then how should I hook it up?
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Old 03-29-2012, 09:03 AM   #15
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You mentioned that you are using an existing AC feed to feed this subpanel.

1) If that feed is still going to be used for that AC, you cannot tap off the AC circuit for the subpanel. That circuit is sized for that AC and nothing else is allowed on the circuit.

2) AC's are typically not 120V/240V. They are strictly 240V which means there is NO NEUTRAL CONTAINED IN THE FEED FOR THE AC. If there was a neutral present, you would have 3 wires...either two blacks and a white, or a black a red and a white.

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