Two phases to house - loss of neutral

[D Yuniskis]

David Nebenzahl wrote:

On 11/23/2009 7:43 PM D Yuniskis spake thus:

Phil Allison wrote:

** In the US and Canada - it is NOT permitted to link neutral
and earth or plumbing within a premises.

"*within* a premises". The neutral *is* "earthed" right outside
the home, typically. The Code goes to great lengths telling
you exactly *how* to earth the mains at the service entrance.

However, this ignores the fact that most residential wiring
is grandfathered into "acceptance". Previously, homes *were*
grounded through their "water main" (e.g., my parents home
has ground at the water meter).

Grounding a home's electrical system through the plumbing is perfectly
safe, and probably the best way to do it, assuming the plumbing is steel
or copper.

This is no longer permitted according to the NEC (American electrical
code). Why? Because not all pipe nowadays is steel or copper. In fact,
one can get into great trouble replumbing part of a house with plastic
and severing an old ground connection.

The water utility (and plumber) doesn't care about how "good" a
ground their water supply is. You get what you get.

OTOH, by *explicitly* mandating that you earth the mains with
an "8 ft rod" (of specific characteristics), you focus on the
ground itself -- as opposed to relying on ground as a "side effect"
of your plumbing!

E.g., I have seen several neighbors have their water service
replumbed from house to street (meter is at the street, here).
Had they relied on water main for earth, they would lose electric
service at the same time.

Also note that in many localities, homeowners are allowed to
do their own *plumbing* but aren't allowed to tamper with the
mains! :> ("Gee, I didn't realize that cutting my water
main to install my own water softener would cause my electric
to go...")

Grounding has changed a *lot* over the years. Most of the
homes I worked on when I was younger were 14/2 in BX. *If*
a ground was used, you often saw the BX's jacket serve that
purpose (or the "drain wire" within). Nowadays, I think
folks would cringe at this use.

So, you can encounter all sorts of different situations
here in the US (I've even worked on homes with knob & tube
wiring!)

I've worked on lots of knob and tube wiring around here (San Francisco
Bay area). It's actually a very good wiring system, and in most cases is
still perfectly safe and functional 60 to 80 years later. It's permitted
to be "grandfathered" in under the NEC, but of course is no longer
installed anymore.

I don't like dealing with the *tar*. :<

 

[Jerry Peters]

whit3rd <whit3rd@gmail.com> wrote:

On Nov 23, 5:38 pm, D Yuniskis <not.going.to...@seen.com> wrote:

Grounding the mains to "plumbing" *was* common in the US many
years ago.  Now, I believe, you *must* ground to a metal
rod driven into the earth (8 ft?).

Just to be clear, my copy of the US National Electric Code clearly
requires (section 250-80) plumbing to be bonded to the electrical
service
ground, it just doesn't allow the buried water piping to substitute
for
a ground rod or similar to-the-soil connection.

The ground wire from the interior water pipe grounds the pipes, not
the
electric wiring.

Maybe no, but certainly not 60 years ago when my house was built.
Grounding via the water supply pipe was resonably standard then.
The problem now is that the water supply pipe is likely to be plastic,
or perhaps partly replaced by plastic. Also the water main is very
likely to be plastic if it's relatively new.

Jerry

 

[Baron]

Sylvia Else wrote:

baron wrote:
Sylvia Else Inscribed thus:

Baron wrote:

Removing the return leg isn't going to cause problems in a
properly wired US home. Don't know about the UK.
The lights would go out ! Domestic properties usually have just a
240v
single phase feed. Usually you would get a single phase running
down one side of the street and another phase running down the
other.

I said I have two phases.

Sylvia.

Yes I know ! I answered the question above !


You think I'm mistaken about having two phases?

Sylvia.

Are you really thick or just pretending.

--
Best Regards:
Baron.

 

[D Yuniskis]

Hi Sylvia,

Sylvia Else wrote:

Are you really thick or just pretending.

I'll opt for neither. So far you've said nothing relevant to the thread,
which concerns a house with two connected phases.

Have we decided that you really have two different *phases*
vs. two different *legs* (but really "single phase" -- think
center tapped transformer).

E.g., 3 phase "220" (US) is three conductors plus a ground.
If you look at any two of those conductors (ground referenced)
you would see a 120 degree PHASE lag between them.

A US residential service is "single phase, 220" in which
you have two 110V circuits ("legs") 180 degrees out of phase
with each other (i.e., the center tapped xformer concept).

So, here, half of your lighting/living circuits are on
one *leg* (so those appliances are nominally 110VAC)
and the other half on the other "leg". Some bigger
loads tend to straddle both legs (220) -- e.g., the
blower motor in the evaporative cooler. Other
appliances *use* both legs but actually as two 110V
*circuits* (i.e., higher ampacity available on two
conductors).

If you think otherwise, try explaining yourself better.

(sigh) There seems to be a *lot* of vitriol in this group.
Sad when you would *think* people were (supposedly)
reasonably intelligent (?). Crappy S/N ratio! :>

--don

 

[Trevor Wilson]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:01059875$0$23368$c3e8da3@news.astraweb.com...

Baron wrote:
Meat Plow wrote:

On Tue, 24 Nov 2009 11:10:26 +1100, Sylvia Else
sylvia@not.at.this.address>wrote:

I have to phases of power supply to my house - so three power lines,
two phases plus neutral.

I've on occasion wondered what would happen if we lost the neutral
line. It seems to me that we'd then have the voltage between the two
phases across two sets of appliances, one set attached to one phase,
and the other set attached to the other phase, with the two sets in
series as a result of their common connection to the neutral wire.
Since the two sets are unlikely to represent equal loads, the net
result would be a large overvoltage on one set of appliances.

My electrician says it's not an issue, but I can't see why.

Any thoughts?

Sylvia.
Removing the return leg isn't going to cause problems in a properly
wired US home. Don't know about the UK.

The lights would go out ! Domestic properties usually have just a 240v
single phase feed. Usually you would get a single phase running down
one side of the street and another phase running down the other.


I said I have two phases.

**You are, at this time, discovering the futility of asking a question that
is specific to Australia, in an international group. Some very quick,
informal examination of the houses nearby (about 50 or so) suggests that
around 10% are single phase connected, another 20% are three phase and the
rest are two phase. In my last home, the figures were more like 30% single
phase, 10% three phase and the rest were two phase. The likely reason was
that in my last home, town gas was available. At my present address, town
gas is not available. There are also larger, more expensive homes where I
live now and these people tend to have more power for various appliances
like pool/spa heaters, big air conditioners et al.

I would hazard a guess that the majority of Australian homes are two phase
connected. And, unlike the US, almost no domestic appliances (outside large
air conditioners and pool heaters) use more than a single phase.

--
Trevor Wilson
www.rageaudio.com.au

 

[Sylvia Else]

D Yuniskis wrote:

Hi Sylvia,

Sylvia Else wrote:
Are you really thick or just pretending.

I'll opt for neither. So far you've said nothing relevant to the
thread, which concerns a house with two connected phases.

Have we decided that you really have two different *phases*
vs. two different *legs* (but really "single phase" -- think
center tapped transformer).

Four wires on the power poles in the street, being a three phase supply.
We have three wires leading from the street, and two power meters, plus
a third meter for the off peak water supply.

Sylvia.

 

[Sylvia Else]

Trevor Wilson wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:01059875$0$23368$c3e8da3@news.astraweb.com...
Baron wrote:
Meat Plow wrote:

On Tue, 24 Nov 2009 11:10:26 +1100, Sylvia Else
sylvia@not.at.this.address>wrote:

I have to phases of power supply to my house - so three power lines,
two phases plus neutral.

I've on occasion wondered what would happen if we lost the neutral
line. It seems to me that we'd then have the voltage between the two
phases across two sets of appliances, one set attached to one phase,
and the other set attached to the other phase, with the two sets in
series as a result of their common connection to the neutral wire.
Since the two sets are unlikely to represent equal loads, the net
result would be a large overvoltage on one set of appliances.

My electrician says it's not an issue, but I can't see why.

Any thoughts?

Sylvia.
Removing the return leg isn't going to cause problems in a properly
wired US home. Don't know about the UK.
The lights would go out ! Domestic properties usually have just a 240v
single phase feed. Usually you would get a single phase running down
one side of the street and another phase running down the other.

I said I have two phases.

**You are, at this time, discovering the futility of asking a question that
is specific to Australia, in an international group.

Oh, I don't know. I've learnt a fair bit in the process.

Those in the US who really have a split single phase rather than two
phases, would experience much the same effects if they lost the centre
(neutral) link back to the transformer.

Sylvia.

 

[PeterD]

On Wed, 25 Nov 2009 17:28:50 -0700, D Yuniskis
<not.going.to.be@seen.com> wrote:

Hi Sylvia,

Sylvia Else wrote:
Are you really thick or just pretending.

I'll opt for neither. So far you've said nothing relevant to the thread,
which concerns a house with two connected phases.

Have we decided that you really have two different *phases*
vs. two different *legs* (but really "single phase" -- think
center tapped transformer).

E.g., 3 phase "220" (US) is three conductors plus a ground.
If you look at any two of those conductors (ground referenced)
you would see a 120 degree PHASE lag between them.

A US residential service is "single phase, 220" in which
you have two 110V circuits ("legs") 180 degrees out of phase
with each other (i.e., the center tapped xformer concept).

So, here, half of your lighting/living circuits are on
one *leg* (so those appliances are nominally 110VAC)
and the other half on the other "leg". Some bigger
loads tend to straddle both legs (220) -- e.g., the
blower motor in the evaporative cooler. Other
appliances *use* both legs but actually as two 110V
*circuits* (i.e., higher ampacity available on two
conductors).

US standard is 240 volts, not 220.

 

[Jamie]

Sylvia Else wrote:

Trevor Wilson wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:01059875$0$23368$c3e8da3@news.astraweb.com...

Baron wrote:

Meat Plow wrote:

On Tue, 24 Nov 2009 11:10:26 +1100, Sylvia Else
sylvia@not.at.this.address>wrote:

I have to phases of power supply to my house - so three power lines,
two phases plus neutral.

I've on occasion wondered what would happen if we lost the neutral
line. It seems to me that we'd then have the voltage between the two
phases across two sets of appliances, one set attached to one phase,
and the other set attached to the other phase, with the two sets in
series as a result of their common connection to the neutral wire.
Since the two sets are unlikely to represent equal loads, the net
result would be a large overvoltage on one set of appliances.

My electrician says it's not an issue, but I can't see why.

Any thoughts?

Sylvia.

Removing the return leg isn't going to cause problems in a properly
wired US home. Don't know about the UK.

The lights would go out ! Domestic properties usually have just a 240v
single phase feed. Usually you would get a single phase running down
one side of the street and another phase running down the other.

I said I have two phases.


**You are, at this time, discovering the futility of asking a question
that is specific to Australia, in an international group.


Oh, I don't know. I've learnt a fair bit in the process.

Those in the US who really have a split single phase rather than two
phases, would experience much the same effects if they lost the centre
(neutral) link back to the transformer.

Sylvia.
Yes we would, and it's a very exciting effect!

 

[D Yuniskis]

PeterD wrote:

On Wed, 25 Nov 2009 17:28:50 -0700, D Yuniskis
not.going.to.be@seen.com> wrote:

Hi Sylvia,

Sylvia Else wrote:
Are you really thick or just pretending.
I'll opt for neither. So far you've said nothing relevant to the thread,
which concerns a house with two connected phases.
Have we decided that you really have two different *phases*
vs. two different *legs* (but really "single phase" -- think
center tapped transformer).

E.g., 3 phase "220" (US) is three conductors plus a ground.
If you look at any two of those conductors (ground referenced)
you would see a 120 degree PHASE lag between them.

A US residential service is "single phase, 220" in which
you have two 110V circuits ("legs") 180 degrees out of phase
with each other (i.e., the center tapped xformer concept).

So, here, half of your lighting/living circuits are on
one *leg* (so those appliances are nominally 110VAC)
and the other half on the other "leg". Some bigger
loads tend to straddle both legs (220) -- e.g., the
blower motor in the evaporative cooler. Other
appliances *use* both legs but actually as two 110V
*circuits* (i.e., higher ampacity available on two
conductors).


US standard is 240 volts, not 220.

If we want to be *pedantic*, there are LOTS of "little
errors" in this discussion! ;-)

 

[Sylvia Else]

D Yuniskis wrote:

Sylvia Else wrote:
D Yuniskis wrote:
Have we decided that you really have two different *phases*
vs. two different *legs* (but really "single phase" -- think
center tapped transformer).

Four wires on the power poles in the street, being a three phase
supply. We have three wires leading from the street, and two power
meters, plus a third meter for the off peak water supply.

I'll ignore the comment about power meters as you can get
power meters with all sorts of internal topologies (i.e.,
I can't deduce anything from that).

So, does *your* house have "phases" A and B dropped to it;
your neighbor gets B & C; *his* neighbor C & A; the large
*business* at the end of the block A B & C, etc.?

My neighbour appears only to have one phase. He commented to me that he
remembered that the previous owner of my property had got a second phase
installed, but didn't know why.

Presumably the power company tries to balance phases.

Sylvia.

 

[D Yuniskis]

Sylvia Else wrote:

D Yuniskis wrote:
Have we decided that you really have two different *phases*
vs. two different *legs* (but really "single phase" -- think
center tapped transformer).

Four wires on the power poles in the street, being a three phase supply.
We have three wires leading from the street, and two power meters, plus
a third meter for the off peak water supply.

I'll ignore the comment about power meters as you can get
power meters with all sorts of internal topologies (i.e.,
I can't deduce anything from that).

So, does *your* house have "phases" A and B dropped to it;
your neighbor gets B & C; *his* neighbor C & A; the large
*business* at the end of the block A B & C, etc.?

I.e. what criteria are used to determine *who* is connected
to *what*?

 

[D Yuniskis]

whit3rd wrote:

On Nov 23, 5:38 pm, D Yuniskis <not.going.to...@seen.com> wrote:

Grounding the mains to "plumbing" *was* common in the US many
years ago. Now, I believe, you *must* ground to a metal
rod driven into the earth (8 ft?).

Just to be clear, my copy of the US National Electric Code clearly
requires (section 250-80) plumbing to be bonded to the electrical
service ground, it just doesn't allow the buried water piping to
substitute for a ground rod or similar to-the-soil connection.

Exactly. And the housing of the circulating pump for your
swimming pool must be grounded as well. But, you don't ground
the *mains* through your circulating pump! :>

The Code tries to anticipate things that *could* become
electrified and grounds them. E.g., exposed beams in a metal
building, etc. But, it doesn't let you use those things
*as* ground!

The ground wire from the interior water pipe grounds the pipes, not
the electric wiring.

Exactly.

However, in years (decades) past, it was common to use the
water main as the ground for the incoming service. This isn't
a reliable way to "earth" the mains (for a variety of reasons).

If you poke around people's homes, you will see all sorts of
"questionable practices" wrt ground. Its a wonder more folks
aren't electrofried! :>

 

[Sylvia Else]

Baron wrote:

Sylvia Else wrote:

baron wrote:
Sylvia Else Inscribed thus:

Baron wrote:
Removing the return leg isn't going to cause problems in a
properly wired US home. Don't know about the UK.
The lights would go out ! Domestic properties usually have just a
240v
single phase feed. Usually you would get a single phase running
down one side of the street and another phase running down the
other.

I said I have two phases.

Sylvia.
Yes I know ! I answered the question above !

You think I'm mistaken about having two phases?

Sylvia.

Are you really thick or just pretending.

I'll opt for neither. So far you've said nothing relevant to the thread,
which concerns a house with two connected phases.

If you think otherwise, try explaining yourself better.

Sylvia.

 

[D Yuniskis]

Sylvia Else wrote:

D Yuniskis wrote:
Sylvia Else wrote:
D Yuniskis wrote:
Have we decided that you really have two different *phases*
vs. two different *legs* (but really "single phase" -- think
center tapped transformer).

Four wires on the power poles in the street, being a three phase
supply. We have three wires leading from the street, and two power
meters, plus a third meter for the off peak water supply.

I'll ignore the comment about power meters as you can get
power meters with all sorts of internal topologies (i.e.,
I can't deduce anything from that).

So, does *your* house have "phases" A and B dropped to it;
your neighbor gets B & C; *his* neighbor C & A; the large
*business* at the end of the block A B & C, etc.?

My neighbour appears only to have one phase. He commented to me that he
remembered that the previous owner of my property had got a second phase
installed, but didn't know why.

So, this is a way of providing you with enough "supply"
to match your needs?

E.g., here, if you need more power, you upgrade your entire
service. I.e., a 60A service might be upgraded to 100A;
100A to 200A, etc. In each case, all of the conductors
coming into the house are increased to a higher ampacity.
(you appear to be able to just "add another leg"?)

Presumably the power company tries to balance phases.

OK.

 

[Sylvia Else]

Leaving the neutral failure issue aside, what would happen if I disabled
the Earth leakage detectors and drew power across the two phases.

Would the two utility meters correctly reflect the energy I consumed?

Sylvia.

 

[Sylvia Else]

Sylvia Else wrote:

Leaving the neutral failure issue aside, what would happen if I disabled
the Earth leakage detectors and drew power across the two phases.

Would the two utility meters correctly reflect the energy I consumed?

Sylvia.

On second thoughts, it's pretty obvious that they wouldn't be correct,
and that I'd be significantly overcharged for the power.

Sylvia.

 

[Thomas Tornblom]

Sylvia Else <sylvia@not.at.this.address> writes:

D Yuniskis wrote:
Sylvia Else wrote:
D Yuniskis wrote:
Have we decided that you really have two different *phases*
vs. two different *legs* (but really "single phase" -- think
center tapped transformer).

Four wires on the power poles in the street, being a three phase
supply. We have three wires leading from the street, and two power
meters, plus a third meter for the off peak water supply.
I'll ignore the comment about power meters as you can get
power meters with all sorts of internal topologies (i.e.,
I can't deduce anything from that).
So, does *your* house have "phases" A and B dropped to it;
your neighbor gets B & C; *his* neighbor C & A; the large
*business* at the end of the block A B & C, etc.?

My neighbour appears only to have one phase. He commented to me that
he remembered that the previous owner of my property had got a second
phase installed, but didn't know why.

Presumably the power company tries to balance phases.

Sylvia.

You can fairly easily identify whether you have a two legged single
phase supply or two phases out of a three phase supply by measuring
the AC voltage between the "phases".

If you get 2 x your single phase voltage you have a two legged single
phase supply. If you get 1.73 x your single phase voltage you have two
phases out of a three phase supply.

Thomas

 

[Thomas Tornblom]

Sylvia Else <sylvia@not.at.this.address> writes:

Sylvia Else wrote:
Leaving the neutral failure issue aside, what would happen if I
disabled the Earth leakage detectors and drew power across the two
phases.
Would the two utility meters correctly reflect the energy I consumed?

yes.

Sylvia.

On second thoughts, it's pretty obvious that they wouldn't be correct,
and that I'd be significantly overcharged for the power.

Sylvia.

No you wouldn't.

Each of the meters will indicate what you draw from the phases, and as
you now have a higher voltage, you will also draw more power, which is
what you are paying for.

Thomas

 

[Trevor Wilson]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:006c3c5f$0$8071$c3e8da3@news.astraweb.com...

Leaving the neutral failure issue aside, what would happen if I disabled
the Earth leakage detectors and drew power across the two phases.

**Depends on the equipment you connected. The damage might range from mild
to catastrophic.

Would the two utility meters correctly reflect the energy I consumed?

**Briefly, yes.


--
Trevor Wilson
www.rageaudio.com.au