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From: Unruh on 15 Oct 2007 13:52
"Robert M. Riches Jr." <spamtrap42(a)verizon.net> writes:

>On 2007-10-14, Unruh <unruh-spam(a)physics.ubc.ca> wrote:
>> "Peter D." <psd(a)live.home.invalid> writes:
>>
>>>on Saturday 13 October 2007 10:13
>>>in the Usenet newsgroup alt.os.linux.mandrake
>>>Adam wrote:
>>
>>>> Peter D. wrote:
>>
>>>[snip]
>>>> I don't know much about this and hope someone will correct me, but as I
>>>> understand it, your typical American house has two 110-120V feeds out of
>>>> phase. The entire house is wired for 120V (plug has vertical prongs
>>>> plus ground pin). Somehow the two feeds are combined to get 220-240V
>>>> (plug has horizontal prongs plus ground pin, or sometimes circular
>>>> prongs), but that's only run to the few places where 240V appliances
>>>> would be, typically the range (stove/oven), clothes dryer, and larger
>>>> air conditioners.
>>
>>>I was assuming each house had a street supply of 220V and a transformer
>>>with a single phase 110V output, but a two phase system could be used.
>>>I am not the man to ask about US power supply techniques.
>>
>> Nope, each house gets 220 volts swinging in opposite phases WRT ground.
>> Thus by using ground ( a big copper rod driven 6 ft into the ground) you
>> get two 110 volt outputs. If something goes wrong with the ground, you get
>> a 220 running through the two phased 110 circuits in series.

>In all installations I have seen, the neutral has been
>supported by a third wire from the transformer on the street
>to the panel in the house. The ground rod does not normally
>carry any substantial amount of current.

You may be right. I would worry about the ground rod getting disconnected,
which would be easy for some homeowner to do, not knowing what in the world
it is for. I am pretty sure that the high voltage line into the street
transformers does use the ground as a return, but could be wrong about that
as well.
From: Robert M. Riches Jr. on 15 Oct 2007 14:04
On 2007-10-15, Unruh <unruh-spam(a)physics.ubc.ca> wrote:
> "Robert M. Riches Jr." <spamtrap42(a)verizon.net> writes:
>
>>On 2007-10-14, Unruh <unruh-spam(a)physics.ubc.ca> wrote:
>>> "Peter D." <psd(a)live.home.invalid> writes:
>>>
>>>>on Saturday 13 October 2007 10:13
>>>>in the Usenet newsgroup alt.os.linux.mandrake
>>>>Adam wrote:
>>>
>>>>> Peter D. wrote:
>>>
>>>>[snip]
>>>>> I don't know much about this and hope someone will correct me, but as I
>>>>> understand it, your typical American house has two 110-120V feeds out of
>>>>> phase. The entire house is wired for 120V (plug has vertical prongs
>>>>> plus ground pin). Somehow the two feeds are combined to get 220-240V
>>>>> (plug has horizontal prongs plus ground pin, or sometimes circular
>>>>> prongs), but that's only run to the few places where 240V appliances
>>>>> would be, typically the range (stove/oven), clothes dryer, and larger
>>>>> air conditioners.
>>>
>>>>I was assuming each house had a street supply of 220V and a transformer
>>>>with a single phase 110V output, but a two phase system could be used.
>>>>I am not the man to ask about US power supply techniques.
>>>
>>> Nope, each house gets 220 volts swinging in opposite phases WRT ground.
>>> Thus by using ground ( a big copper rod driven 6 ft into the ground) you
>>> get two 110 volt outputs. If something goes wrong with the ground, you get
>>> a 220 running through the two phased 110 circuits in series.
>
>>In all installations I have seen, the neutral has been
>>supported by a third wire from the transformer on the street
>>to the panel in the house. The ground rod does not normally
>>carry any substantial amount of current.
>
> You may be right. I would worry about the ground rod getting disconnected,
> which would be easy for some homeowner to do, not knowing what in the world
> it is for. I am pretty sure that the high voltage line into the street
> transformers does use the ground as a return, but could be wrong about that
> as well.

All the installations I have seen have had a metal wire for
return of even the high voltage (lower current) primary.

--
Robert Riches
spamtrap42(a)verizon.net
(Yes, that is one of my email addresses.)
From: Unruh on 15 Oct 2007 16:35
"Robert M. Riches Jr." <spamtrap42(a)verizon.net> writes:

>On 2007-10-15, Unruh <unruh-spam(a)physics.ubc.ca> wrote:
>> "Robert M. Riches Jr." <spamtrap42(a)verizon.net> writes:
>>
>>>On 2007-10-14, Unruh <unruh-spam(a)physics.ubc.ca> wrote:
>>>> "Peter D." <psd(a)live.home.invalid> writes:
>>>>
>>>>>on Saturday 13 October 2007 10:13
>>>>>in the Usenet newsgroup alt.os.linux.mandrake
>>>>>Adam wrote:
>>>>
>>>>>> Peter D. wrote:
>>>>
>>>>>[snip]
>>>>>> I don't know much about this and hope someone will correct me, but as I
>>>>>> understand it, your typical American house has two 110-120V feeds out of
>>>>>> phase. The entire house is wired for 120V (plug has vertical prongs
>>>>>> plus ground pin). Somehow the two feeds are combined to get 220-240V
>>>>>> (plug has horizontal prongs plus ground pin, or sometimes circular
>>>>>> prongs), but that's only run to the few places where 240V appliances
>>>>>> would be, typically the range (stove/oven), clothes dryer, and larger
>>>>>> air conditioners.
>>>>
>>>>>I was assuming each house had a street supply of 220V and a transformer
>>>>>with a single phase 110V output, but a two phase system could be used.
>>>>>I am not the man to ask about US power supply techniques.
>>>>
>>>> Nope, each house gets 220 volts swinging in opposite phases WRT ground.
>>>> Thus by using ground ( a big copper rod driven 6 ft into the ground) you
>>>> get two 110 volt outputs. If something goes wrong with the ground, you get
>>>> a 220 running through the two phased 110 circuits in series.
>>
>>>In all installations I have seen, the neutral has been
>>>supported by a third wire from the transformer on the street
>>>to the panel in the house. The ground rod does not normally
>>>carry any substantial amount of current.
>>
>> You may be right. I would worry about the ground rod getting disconnected,
>> which would be easy for some homeowner to do, not knowing what in the world
>> it is for. I am pretty sure that the high voltage line into the street
>> transformers does use the ground as a return, but could be wrong about that
>> as well.

>All the installations I have seen have had a metal wire for
>return of even the high voltage (lower current) primary.

In our area there is only one single high voltage wire. There are three
things. There is the high voltage three phase which comes into the
neighbourhood, which runs to a transformer which converts it to single
phase. That is then fed to the transformers outside the house where it is
converted to 2phase 110. As far as I can see there is no return wire on
that single phase high voltage line.

From: Moe Trin on 15 Oct 2007 20:26
On Sun, 14 Oct 2007, in the Usenet newsgroup alt.os.linux.mandrake, in article
<DTwQi.10554$GO5.4887(a)edtnps90>, Unruh wrote:

>No. The transformer is on the pole outside your and your neighbour's
>house.

Some communities require the utilities (electrical, phone, cable) to be
underground. As such, the transformers are on concrete pads, often
hidden by bushes. Generally, this is "newer" neighborhoods (ours is 18
years old) in areas were weather MIGHT be a contributing factor (we
get rather violent thunderstorms two/three times a year).

>600---- ---------------------- +110
> S C
> S C________
> S C -
> ___S C .
> | C______________________ -110
> _
> -
> .

The lowest voltage used on the primary in the states is MUCH higher than
600 Volts. 2300 Volts is getting rare, 4160 more common, and 13200
more so (mainly for aerial feeds). Regional feeds (which connect
sub-stations where transformers drop the voltage to street distribution
levels) are invariably high voltage (66KV <-> 1 MV) three phase. Major
feeds, such as the line from the Columbia River in Oregon/Washington
down to Los Angeles, may well be very high voltage DC (+/-500 KV for
the Western Grid Tie).

>600 or 2000 on the supply side. You know, that single wire way up at
>the top of the poles, with big glass conductors setting it off from
>the poles? (ground is the return path. Cheaper than copper).

Single wire is quite uncommon. A more normal situation is a grounded
bare wire as high as practical on the pole and below that, one two three
wires that may or may not be insulated (obviously supported by ceramic
insulators at the poles). The grounded bare wire is for lightning
protection, although it does serve as a return as well. Depending on
the regulations, there is USUALLY a ground rod at each pole.

Old guy
From: Peter D. on 15 Oct 2007 20:58
on Tuesday 16 October 2007 03:34
in the Usenet newsgroup alt.os.linux.mandrake
Robert M. Riches Jr. wrote:

[snip]
> In all installations I have seen, the neutral has been
> supported by a third wire from the transformer on the street
> to the panel in the house. The ground rod does not normally
> carry any substantial amount of current.

Typically the earth wire is designed to carry *large* currants
in ABnormal situations.


--
sig goes here...
Peter D.
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