I get confused - 240 circuits

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  #1  
Old 10-25-02, 07:55 PM
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I get confused - 240 circuits

i get confused on the purpose of ground and netrual on 240 circuits, Some like stove and dryers take both and then some like water heater and air handles just take grounds. since they both tie in the main box at same location, someone please explain this to me.
 
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Old 10-25-02, 08:04 PM
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The purpose of a grounding wire is the same for all circuits. It is there to carry current only in the event of a fault. In the absense of a fault, the grounding wire never carries any current.

The purpose of a neutral wire is the same as the purpose of any current-carrying conductor. It's purpose is to carry current. A pure 240 volt circuit never needs a neutral. A neutral is only needed for 120 volt circuits. The reason some appliances such as dryers have a neutral is that they are really a combination of a 240-volt appliance and a 120-volt appliance. The neutral is there only for the 120-volt part.

Dryers use 240 volts for heat and 120 volts for controls and for the drum motor.

A hot water heater uses 240 volts for everything, and thus needs no neutral.

Some stoves use 120 volts for such things as a clock. Other stoves use no 120.

Just because the neutral and a ground both connect at the same place at the panel should not cause you for one second to think they have anything else in common.

P.S. Dryer and range circuits installed prior to 1996 are special, in that they use one wire for both neutral and grounding. As you most likely know, this is no longer permitted for new installations, and wasn't really a great idea in the first place.
 
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Old 10-25-02, 11:32 PM
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John, my dryer also has a low heat setting which uses 120V.
 
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Old 10-26-02, 06:41 AM
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Thanks sberry for the clarification. I was unaware that some dryers did that. What brand is it?
 
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Old 10-26-02, 09:47 AM
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Its a Westing house,, called a Three temp,,, regular, Med and none for heat
 
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