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Old 10-30-2010, 05:00 PM   #1
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why no neutral?


I understand that a water heater does not use a white neutral, only an equipment ground. (I could have saved money and bought 6/2 wire instead of the 6/3).

What I don't get is why ???

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Old 10-30-2010, 05:49 PM   #2
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why no neutral?


The highest wattage a residential water heater can be is 5500 watts=30 amps@240=#10 awg! Normally they are 4500 watts.

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Old 10-30-2010, 05:53 PM   #3
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why no neutral?


because it isn't needed.


your house system provides 2 voltages: 120 and 240. The 120 is sourced by a hot and a neutral and the 240 from two hots on opposing legs. While there are some appliances that require 120 and 240 (120/240 volt circuit), there are also appliances that need only one or the other. In those 120/240 circuits, you would have the two hots plus the neutral.

a dryer as an example typically requires a 120/240 circuit. That indicates both 120 and 240 volt sources are needed. The heating element uses the 240 and the controls typically use the 120.

most residential water heaters are pretty low tech with mechanical thermostats and overloads so they do not need the 120 volts typically used in control circuits such as with the dryer.

the reason the 240 volts is used is as simple as: it allows a lower (amperage) rated circuit to feed it. If you need a 30 amp circuit with 240 volts, you would need a 60 amp circuit with 120. The costs of the equipment needed is considerable higher so they use the higher voltage.

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Old 10-30-2010, 07:30 PM   #4
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why no neutral?


thank you Nap for that explanation. Oh BTW Bobelectric, I meant to say 8 romex not 10 as my water heater is on a couple of 40 amp breakers.

The part I'm not clear on is if we only need the equipment ground to run a pair of 120 legs, why do we have separate neutral and equipment grounds on 120 circuits? Probably a dumb question but I'm no Einstein.
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Old 10-30-2010, 07:36 PM   #5
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why no neutral?


Quote:
Originally Posted by handifoot View Post

The part I'm not clear on is if we only need the equipment ground to run a pair of 120 legs, why do we have separate neutral and equipment grounds on 120 circuits? Probably a dumb question but I'm no Einstein.
the egc (equipment grounding conductor) and the neutral must be isolated from each other any place other than the first means of disconnect for the service. The neutral is a current carrying conductor and needs to be treated as such.

so, anytime you run a 120 volt circuit, you have to have a neutral.

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