On 10/17/2011 5:48 PM, spamtrap1888 wrote:
> On Oct 17, 5:05 pm, > wrote:
>> On 10/17/2011 1:30 PM, spamtrap1888 wrote:
>>
>>
>>
>>> On Oct 17, 4:20 pm, > wrote:
>>>> On 10/16/2011 11:49 AM, Lou Decruss wrote:
>>
>>>>> On Sun, 16 Oct 2011 13:54:25 -0700 (PDT), dsi1
>>>>> > wrote:
>>
>>>>>> On Oct 16, 10:10 am, > wrote:
>>>>>>> On Oct 16, 1:09 pm, > wrote:
>>
>>>>>>>> The fourth wire is the wire that your wiring uses for the 120V
>>>>>>>> appliances. It is used in conjunction with one of the 120V lines to
>>>>>>>> supply power for the control systems and the oven light.
>>
>>>>>>> dsi is talking about the neutral wire.
>>
>>>>>> When I was going to electronics school, the instructor used to call it
>>>>>> the return. Is the term "return" ever used by electricians? Thanks.
>>
>>>>> I've never heard it used. It handles the balance of the load between
>>>>> phases. Return doesn't make much sense as AC current isn't
>>>>> directional. I guess if you're sharing a neutral between phases I can
>>>>> see how he/she used the term. If you put an amprobe on a perfectly
>>>>> balanced panel the incoming neutral will read zero. The same will
>>>>> happen out in the field. It's damn near impossible to have that
>>>>> situation in the real world.
>>
>>>> My guess is that the return path is mostly a power generation term. I
>>>> haven't seen the word used in household wiring either. I was looking for
>>>> one of those hot wire probes that used your body to light up the neon
>>>> indicator. They don't seem to sell them anymore. Dangit!
>>
>>> Return path is a DC circuit term.
>>
>> Thanks for the info.
>>
>>
>>
>>> Lou explained what's going on in house wiring. Each hot lead serves as
>>> the "return" for the other. But, if the loads are unbalanced, then
>>> current will flow on the neutral, proportional to the imbalance.
>>
>> I guess you could see it that way but the neutral wire would really be
>> used in conjunction with one of the hot wires to provide power to the
>> subsystems so even if you're not using the 220 circuit, current still
>> flows through the neutral.
>>
>> OTOH, I haven't really studied the circuit for a modern electronic
>> stove. You could make an electronic stove that doesn't need a neutral
>> but that would add complexity. The chassis should still be grounded though.
>
> Finding a diagram of how household wiring works is hard as hell. This
> is the best I could find. Scroll down to the figure Step-down
> transformer with center-tapped secondary winding. The top and bottom
> leads are the hots, while the center tap is the neutral. Scrolling to
> the next figure makes it clear: the two hot leads are 180 degrees out
> of phase.
My thinking is the "return" is the wire coming out of the power station
which carries the current back back to the station. Outside of your
house, the high voltage line and return go through one side of a
transformer and gets converted to 2 120V legs which are 180 degrees out
of phase with each other and a center-tap which is common or neutral to
both legs. My guess is that's why "return" is not used at the home user
level.
>
> If you like to think in terms of the "return," then the neutral line
> is the "return" for both hot leads. Except, if the loads are exactly
> balanced (Figure on next page, entitled "Split phase system draws half
> the current of 125 A at 240 Vac compared to 120 Vac system.") zero
> current flows on the neutral. Again, if the loads are unbalanced,
> current will flow in the neutral.
I agree that the stove presents an unbalanced load. You could probably
design a balanced-load stove but appliances tend to be primitive in
build and wiring and evidently it doesn't matter much. My guess is that
it all averages out in the end.
>
> Now, in the case of the 240 VAC powered range, the lamps, timers,
> spark lighters, etc., will likely be hooked between one hot lead and
> neutral. Thus the range will generate an unbalanced load. But if other
> appliances are drawing current, they may cancel out the current
> injected into the neutral by the range.
>
> http://www.web-books.com/eLibrary/ON...077MB1396.html