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Old 05-03-2009, 02:25 PM   #1
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eletrical


ok, i need to run a single phase 220v circuit ,


question should i run 2 hot wire only,or two hot and a neutral

thanks

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Old 05-03-2009, 02:54 PM   #2
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eletrical


I need to change the oil in my car. What type of oil and how much do I use?

Do you see a correlation between our two questions?
There is a lot of information missing.


240v = two hots
120/240v = two hots and a neutral (sometimes incorrectly referred to as 240v/4-wire)
Grounds are always required.

What size is the load?
What size circuit are you going to run?

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Old 05-03-2009, 03:05 PM   #3
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Most 240V circuits are dedicated to something like a dryer or a big 240V AC window unit. If you run a 120/240V circuit, you could use it for most anything (if it could carry the amperage of the device/appliance it was connected to). It depends on the device, and the receptacle you install for the connection. If you don't need the neutral, you could just wirenut it off and not use it. However, if you need 120/240 for something, the neutral must be present.

Couldn't find anything in the NEC that addresses use of a 120/240V circuit for a straight 240V device. Perhaps one of out more knowledgeable members will educate us on this.
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Old 05-03-2009, 03:20 PM   #4
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Quote:
Originally Posted by Bigplanz View Post
Most 240V circuits are dedicated to something like a dryer or a big 240V AC window unit.
With the exception of the odd European model, EVERY electric dryer I have ever seen for the American market required a 120/240v circuit, not a 240v circuit.
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Old 05-03-2009, 03:24 PM   #5
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Thank you.
ok let me expain more ,i am planning to install an AC unit which requries 220v single phase.I have a 120v outlet right there,with 2 wires and a ground AWG12,what is the best way to get what i need to get that unit running ,can i use the ground for neutral,and the black and white for hot.
ty
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Old 05-03-2009, 03:31 PM   #6
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eletrical


Thank you.
ok let me expain more ,i am planning to install an AC unit which requries 220v single phase.I have a 120v outlet right there,with 2 wires and a ground AWG12,what is the best way to get what i need to get that unit running ,can i use the ground for neutral,and the black and white for hot.
ty
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Old 05-03-2009, 03:35 PM   #7
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Quote:
Originally Posted by philhvacr View Post
Thank you.
ok let me expain more ,i am planning to install an AC unit which requries 220v single phase.I have a 120v outlet right there,with 2 wires and a ground AWG12,what is the best way to get what i need to get that unit running ,can i use the ground for neutral,and the black and white for hot.
ty
Never use the ground for neutral. In re: the 120 outlet wired with 12 gauge wire, I see no reason why you couldn't convert it to 240V use by using the white as hot (marked with black tape at each end to mark it hot). No neutral would be required with a straight 240V circuit, though a ground is always required. If your AC unit is 120/240V (I've never seen one, but they may exist for all I know) then you can't use the 120V circuit as there is no way to provide a neutral with 12-2.

I used 240V in a generic sense when I referred to a 240V circuit usually being dedicated to a specific appliance or device like a dryer or AC unit. Dryers are all 120/240V appliances to the best of my knowledge.

If there is some code reason why you can't convert a 120V circuit with 12-2 to a 240V use, I am sure some one will explain it to us.
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Old 05-03-2009, 03:55 PM   #8
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This idea will work provided the following conditions are met.

1) The outlet in question is dedicated. Meaning there are no other outlets on the circuit.

2) There is enough extra space in the panel to replace the existing single pole breaker with a two pole one. The two spaces where the breaker goes must be stacked one on top of the other.

3) The nameplate on the A/C unit states that it can be operated on a 15 or 20 amp branch circuit. This will dictate the breaker size.

4) The outlet is changed to match the cord plug on the unit, and the breaker size doesn't exceed the new receptacle rating and is a single , not duplex.

Check carefully whether the outlet in question is indeed dedicated. If there are other outlets on the same circuit, anything plugged into them will be destroyed.

Rob
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Old 05-03-2009, 06:10 PM   #9
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Originally Posted by micromind View Post
This idea will work provided the following conditions are met.

1) The outlet in question is dedicated. Meaning there are no other outlets on the circuit.

Rob
Excellent point. A 120V circuit probably has several receptacles or lights, etc. connected to it, thus rendering it unsuitable for easy conversion to 240V.

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