Clarification on wiring issue

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  #1  
Old 03-04-05, 06:00 AM
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Clarification on wiring issue

Using 14/3 to wire a kitchen plug you connect one hot wire to the hot side of a receptacle and the neutral to the other. The other hot wire is used to connect to the other hot terminal of the same receptical. They share the neutral? If I plug in a coffee maker at 200watts into the top of this receptical I will read equal amounts of current on both the hot and neutral legs of this circuit. But if I plug in a 600w microwave along with the coffee maker I will only read 400w in the neutral wire? In essence it changes from two 120v circuits to one 240v circuit?

Please clarifiy this for me thankyou...
 
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Old 03-04-05, 06:26 AM
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In the example you are using you MUST break the tab on between the two hot terminals or you will create a short, cause lots of fireworks and hopefully trip the breaker(s).

This is a multi wire circuit. The two hot wires share the same neutral. The two hot wires MUST come from different legs of the incoming service. If you used an oscilloscope to examine the hot lines, you would see two sine waves at a frequency of 60 hertz, but the two sine waves would be opposite each other, or out of phase.

If all you have plugged in is a 200 watt appliance (and it is actually using 200 watts) you will read equal current (approximately 1.67 amps) on one hot wire and on the neutral wire.

If you then plug in a 600 watt appliance into the other receptacle (and it is actually drawing 600 watts) then the current required by the 600 watt appliance is 5 amps. However, the current on the neutral is the difference between them, or 5 - 1.67 = 3.33 amps.

However, you do not have a 240 volt circuit. You have two 120 volt circuits that share a common neutral, or a multi wire circuit. Assuming that you wire everything properly, you can't get 240 volts out unless a fault occurs somewhere along the circuit or unless you intentionally connect to both hot wires.
 
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Old 03-04-05, 08:58 AM
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#12 wire with an ampacity of 20 amps is required for kitchen and dining-room receptacle-outlets.
 
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Old 03-04-05, 03:34 PM
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Bob I am wondering what happens to the extra current, why just the difference returning on the neutrals and not the sum?
 
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Old 03-04-05, 04:29 PM
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I simplified terms current flowing though one hot cancels current flowing though the other hot. Only the difference in current flows though the neutral.
 
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