I am in the UK.

I would like to take a stereo signal from the line-out of my stereo
(or TV) to the line-in of my PC.

The equipment is in different rooms and the audio cable would be 10
metres. It will be this type:
http://www.maplin.co.uk/images/full/130i0.jpg

I don't understand the technical side but is 10 metres so long that
it might cause audio problems with things like frequency response or
voltage/current levels and so on?

Will I need to get some higher specification audio cable to cover
that distance? I want to keep cost down.

Andy wrote:
I am in the UK.

I would like to take a stereo signal from the line-out of my stereo
(or TV) to the line-in of my PC.

The equipment is in different rooms and the audio cable would be 10
metres. It will be this type:
http://www.maplin.co.uk/images/full/130i0.jpg

I don't understand the technical side but is 10 metres so long that
it might cause audio problems with things like frequency response or
voltage/current levels and so on?

Will I need to get some higher specification audio cable to cover
that distance? I want to keep cost down.

I have used similar cable for a similar purpose over longer distances
with no problems, for general purpose "listening" quality. Buying a
higher spec cable is only going to give a very marginal improvement - if
you really are interested in quality, you would link digital ports using
an optical cable and not use analogue, anyway.

--
Sue

On Tue, 18 Apr 2006 22:35:53 +0100, Andy wrote:

I would like to take a stereo signal from the line-out of my stereo
(or TV) to the line-in of my PC.

The equipment is in different rooms and the audio cable would be 10
metres. It will be this type:
http://www.maplin.co.uk/images/full/130i0.jpg

I don't understand the technical side but is 10 metres so long that
it might cause audio problems with things like frequency response or
voltage/current levels and so on?

Will I need to get some higher specification audio cable to cover
that distance? I want to keep cost down.

You might get unacceptable noise pickup, you might not. Try. You
might also get hum. Sometimes it responds to simply lifting the
screen connection at one end, sometimes you need an isolating
transformer. Or rather a pair of them.

What's the link for?

"Andy" wrote ...
I am in the UK.

I would like to take a stereo signal from the line-out of my stereo
(or TV) to the line-in of my PC.

The equipment is in different rooms and the audio cable would be 10
metres. It will be this type:
http://www.maplin.co.uk/images/full/130i0.jpg

I don't understand the technical side but is 10 metres so long that
it might cause audio problems with things like frequency response or
voltage/current levels and so on?

Will I need to get some higher specification audio cable to cover
that distance? I want to keep cost down.

The cable is most likely just fine. However beware of
ground loops and other hazards of running audio over
long distances. These have little to do with the cable.

Will I need to get some higher specification audio cable to cover that
distance? I want to keep cost down.

The cable is most likely just fine. However beware of
ground loops and other hazards of running audio over
long distances. These have little to do with the cable.

Expanding on that a little:

My "trans-workshop cable" is about 8 metres long and works perfectly. It's
cheap audio cable (shielded of course).

The equipment on both ends is powered from the same electrical circuit and I
don't have ground loop problems. You would have ground loop problems if the
equipment were powered from different circuits. I gather that you are in
the UK (hence "ring" wiring structure, which I like, instead of the American
daisychain) and that everything is in the same room. It should work fine.

mc spake thus:

I gather that you are in the UK (hence "ring" wiring structure, which
I like, instead of the American daisychain) and that everything is
in the same room. It should work fine.

So how does house wiring work in the UK? Is there more than one
grounding ("earthing") point? And how is this better?

(Here, the Merkin practice is to ground the "service panel"--the box
where the big wires come into the house--to a single ground rod, with
everything running downstream from that.)

By the way, this brings up a strange experience I had recently doing
some wiring. I was working for a guy who owns two houses right next to
each other, and he wanted to run a cable TV connection from one house to
the other. I was about to connect the cable in the attic of the house
that was the source of the signal when I got a little tingle. After
grabbing a VOM, it turned out that there was about a 20 volt difference
between the two cable grounds.

Was this due to power line potential differences, or to cable signal
potential differences, or something else? The cable guys do their own
grounding outside, and I don't think they put in any bonds to the
electric service ground. In any case, the whole project was abandoned
then and there as a bad idea. (It occurred to me that a cable
transformer could have solved the problem, but then so could doing the
thing the right way: just getting both houses wired for cable.)


--
Pierre, mon ami. Jetez encore un Scientologiste
dans le baquet d'acide.

- from a posting in alt.religion.scientology titled
"France recommends dissolving Scientologists"

David Nebenzahl wrote:

mc spake thus:

I gather that you are in the UK (hence "ring" wiring structure, which
I like, instead of the American daisychain) and that everything is
in the same room. It should work fine.


So how does house wiring work in the UK? Is there more than one
grounding ("earthing") point? And how is this better?

(Here, the Merkin practice is to ground the "service panel"--the box
where the big wires come into the house--to a single ground rod, with
everything running downstream from that.)

By the way, this brings up a strange experience I had recently doing
some wiring. I was working for a guy who owns two houses right next to
each other, and he wanted to run a cable TV connection from one house to
the other. I was about to connect the cable in the attic of the house
that was the source of the signal when I got a little tingle. After
grabbing a VOM, it turned out that there was about a 20 volt difference
between the two cable grounds.

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Your tingle was because your equipment is not grounded, and is perfectly normal.

--
Eiron

No good deed ever goes unpunished.

Eiron spake thus:

David Nebenzahl wrote:

mc spake thus:

I gather that you are in the UK (hence "ring" wiring structure, which
I like, instead of the American daisychain) and that everything is
in the same room. It should work fine.

So how does house wiring work in the UK? Is there more than one
grounding ("earthing") point? And how is this better?

(Here, the Merkin practice is to ground the "service panel"--the box
where the big wires come into the house--to a single ground rod, with
everything running downstream from that.)

By the way, this brings up a strange experience I had recently doing
some wiring. I was working for a guy who owns two houses right next to
each other, and he wanted to run a cable TV connection from one house
to the other. I was about to connect the cable in the attic of the
house that was the source of the signal when I got a little tingle.
After grabbing a VOM, it turned out that there was about a 20 volt
difference between the two cable grounds.

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Your tingle was because your equipment is not grounded, and is perfectly
normal.

No, my tingle was because I was holding two cables strung between two
different houses, each grounded at its end. Doesn't seem normal at all
to me.


--
Pierre, mon ami. Jetez encore un Scientologiste
dans le baquet d'acide.

- from a posting in alt.religion.scientology titled
"France recommends dissolving Scientologists"

On Tue, 18 Apr 2006 23:32:56 -0700, David Nebenzahl
wrote:

Eiron spake thus:

David Nebenzahl wrote:

mc spake thus:

I gather that you are in the UK (hence "ring" wiring structure, which
I like, instead of the American daisychain) and that everything is
in the same room. It should work fine.

So how does house wiring work in the UK? Is there more than one
grounding ("earthing") point? And how is this better?

(Here, the Merkin practice is to ground the "service panel"--the box
where the big wires come into the house--to a single ground rod, with
everything running downstream from that.)

By the way, this brings up a strange experience I had recently doing
some wiring. I was working for a guy who owns two houses right next to
each other, and he wanted to run a cable TV connection from one house
to the other. I was about to connect the cable in the attic of the
house that was the source of the signal when I got a little tingle.
After grabbing a VOM, it turned out that there was about a 20 volt
difference between the two cable grounds.

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Your tingle was because your equipment is not grounded, and is perfectly
normal.

No, my tingle was because I was holding two cables strung between two
different houses, each grounded at its end. Doesn't seem normal at all
to me.

Most likely the two houses weren't on the same phase of the three
phase supply to the street. Their two grounds could have been doing
very different things voltage-wise. You should always have an
isolation transformer in a connection like this.

d

--
Pearce Consulting
http://www.pearce.uk.com

Don Pearce spake thus:

On Tue, 18 Apr 2006 23:32:56 -0700, David Nebenzahl
wrote:

Eiron spake thus:

David Nebenzahl wrote:

mc spake thus:

I gather that you are in the UK (hence "ring" wiring structure, which
I like, instead of the American daisychain) and that everything is
in the same room. It should work fine.

So how does house wiring work in the UK? Is there more than one
grounding ("earthing") point? And how is this better?

(Here, the Merkin practice is to ground the "service panel"--the box
where the big wires come into the house--to a single ground rod, with
everything running downstream from that.)

By the way, this brings up a strange experience I had recently doing
some wiring. I was working for a guy who owns two houses right next to
each other, and he wanted to run a cable TV connection from one house
to the other. I was about to connect the cable in the attic of the
house that was the source of the signal when I got a little tingle.
After grabbing a VOM, it turned out that there was about a 20 volt
difference between the two cable grounds.

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Your tingle was because your equipment is not grounded, and is perfectly
normal.

No, my tingle was because I was holding two cables strung between two
different houses, each grounded at its end. Doesn't seem normal at all
to me.

Most likely the two houses weren't on the same phase of the three
phase supply to the street. Their two grounds could have been doing
very different things voltage-wise. You should always have an
isolation transformer in a connection like this.

I seriously doubt that, because then the potential would have been more
like 120 volts, right? I think that's grasping at straws: so far as I
know, PG&E (local electricity dealer) doesn't even supply 3-phase to
residential customers. In fact, not even in come commercial districts. I
owned a small business in Berkeley (print shop) until last year, and I
remember the previous owner telling me about all the headaches he had in
having PG&E put in a 3-phase converter (in an underground vault below
the sidewalk outside). So I know that utility lines don't usually carry
3-phase power, except to large industrial customers.


--
Pierre, mon ami. Jetez encore un Scientologiste
dans le baquet d'acide.

- from a posting in alt.religion.scientology titled
"France recommends dissolving Scientologists"

On Tue, 18 Apr 2006 23:49:28 -0700, David Nebenzahl
wrote:

Don Pearce spake thus:

On Tue, 18 Apr 2006 23:32:56 -0700, David Nebenzahl
wrote:

Eiron spake thus:

David Nebenzahl wrote:

mc spake thus:

I gather that you are in the UK (hence "ring" wiring structure, which
I like, instead of the American daisychain) and that everything is
in the same room. It should work fine.

So how does house wiring work in the UK? Is there more than one
grounding ("earthing") point? And how is this better?

(Here, the Merkin practice is to ground the "service panel"--the box
where the big wires come into the house--to a single ground rod, with
everything running downstream from that.)

By the way, this brings up a strange experience I had recently doing
some wiring. I was working for a guy who owns two houses right next to
each other, and he wanted to run a cable TV connection from one house
to the other. I was about to connect the cable in the attic of the
house that was the source of the signal when I got a little tingle.
After grabbing a VOM, it turned out that there was about a 20 volt
difference between the two cable grounds.

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Your tingle was because your equipment is not grounded, and is perfectly
normal.

No, my tingle was because I was holding two cables strung between two
different houses, each grounded at its end. Doesn't seem normal at all
to me.

Most likely the two houses weren't on the same phase of the three
phase supply to the street. Their two grounds could have been doing
very different things voltage-wise. You should always have an
isolation transformer in a connection like this.

I seriously doubt that, because then the potential would have been more
like 120 volts, right? I think that's grasping at straws: so far as I
know, PG&E (local electricity dealer) doesn't even supply 3-phase to
residential customers. In fact, not even in come commercial districts. I
owned a small business in Berkeley (print shop) until last year, and I
remember the previous owner telling me about all the headaches he had in
having PG&E put in a 3-phase converter (in an underground vault below
the sidewalk outside). So I know that utility lines don't usually carry
3-phase power, except to large industrial customers.

Why would it be 120V? The voltage would depend on how stiff the ground
is round your way. As for three phase supply, no, individual domestic
properties generally don't get that, but streets certainly do - that
is the efficient way to deliver power.

Could be different where you are,of course.

d

--
Pearce Consulting
http://www.pearce.uk.com

On Tue, 18 Apr 2006 23:49:28 -0700, David Nebenzahl
wrote:

I seriously doubt that, because then the potential would have been more
like 120 volts, right? I think that's grasping at straws: so far as I
know, PG&E (local electricity dealer) doesn't even supply 3-phase to
residential customers. In fact, not even in come commercial districts. I
owned a small business in Berkeley (print shop) until last year, and I
remember the previous owner telling me about all the headaches he had in
having PG&E put in a 3-phase converter (in an underground vault below
the sidewalk outside). So I know that utility lines don't usually carry
3-phase power, except to large industrial customers.

There'll probably be 3 phases in the street. houses, or groups of
houses will be allocated a single phase.

I
I seriously doubt that, because then the potential would have been more
like 120 volts, right? I think that's grasping at straws: so far as I
know, PG&E (local electricity dealer) doesn't even supply 3-phase to
residential customers. In fact, not even in come commercial districts. I
owned a small business in Berkeley (print shop) until last year, and I
remember the previous owner telling me about all the headaches he had in
having PG&E put in a 3-phase converter (in an underground vault below
the sidewalk outside). So I know that utility lines don't usually carry
3-phase power, except to large industrial customers.



What they tend to do is supply the area with a three phase line at
around 11Kv and transform that down and then supply house number one
with phase one, house two with phase two, three with phase three, four
with phase one, five with phase two, house six with phase three and so
on. Its called load balancing between the phases...
--
Tony Sayer

"David Nebenzahl" wrote ...
No, my tingle was because I was holding two cables strung between two
different houses, each grounded at its end. Doesn't seem normal at all
to me.

If they were each properly "grounded", you would NOT
have seen any voltage differential. BY DEFINITION.

(Or else the two houses were on differen planets. :-)

"Laurence Payne" wrote...
There'll probably be 3 phases in the street. houses, or
groups of houses will be allocated a single phase.

Not in the parts of the USA where I have lived (up and down
the west coast). They break up the 3 phases back at the main
road and supply only one of the phases to each street (or 2-3
streets depending on the load) It is not economical to run all
3 phases along residential (or even small business) areas.

"Richard Crowley" wrote in message
...
"David Nebenzahl" wrote ...
No, my tingle was because I was holding two cables strung between two
different houses, each grounded at its end. Doesn't seem normal at all to
me.

If they were each properly "grounded", you would NOT
have seen any voltage differential. BY DEFINITION.

I would almost bet that at least one of them wasn't really grounded (to the
earth).

Second choice is that high voltage is being conducted directly into the
earth from some kind of unintended connection. A bad thing.

"David Nebenzahl" wrote in message
.com...
mc spake thus:

I gather that you are in the UK (hence "ring" wiring structure, which
I like, instead of the American daisychain) and that everything is
in the same room. It should work fine.

So how does house wiring work in the UK? Is there more than one grounding
("earthing") point? And how is this better?

As I understand it, the British ring system is to wire the outlets in a room
in a ring so that each of them has two parallel paths to the point where
power enters the room. As a result, a single high-resistance connection
anywhere in the ring will have almost no effect. That should do a more
reliable job of tying together all the ground connections for the different
pieces of equipment.

"Eiron" wrote in message
...

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Two boxes with 3-wire plugs?

Could you elaborate? I thought a ground loop was due to difference in
potential of the ground connections of 2 different pieces of equipment.

On Wed, 19 Apr 2006 07:26:25 -0700, "Richard Crowley"
wrote:

"Laurence Payne" wrote...
There'll probably be 3 phases in the street. houses, or
groups of houses will be allocated a single phase.

Not in the parts of the USA where I have lived (up and down
the west coast). They break up the 3 phases back at the main
road and supply only one of the phases to each street (or 2-3
streets depending on the load) It is not economical to run all
3 phases along residential (or even small business) areas.

So what do they do when somebody asks for three phase supply? Even a
reasonably small business here in the UK might well do that if their
power needs are significant. The power companies here actually prefer
to supply businesses that way, particularly if they are also careful
about their power factor correction.

Or are zoning laws in the States such that it is not possible to set
up a business in an otherwise residential area?

d

--
Pearce Consulting
http://www.pearce.uk.com

On Wed, 19 Apr 2006 10:33:13 -0400, "mc"
wrote:


"David Nebenzahl" wrote in message
s.com...
mc spake thus:

I gather that you are in the UK (hence "ring" wiring structure, which
I like, instead of the American daisychain) and that everything is
in the same room. It should work fine.

So how does house wiring work in the UK? Is there more than one grounding
("earthing") point? And how is this better?

As I understand it, the British ring system is to wire the outlets in a room
in a ring so that each of them has two parallel paths to the point where
power enters the room. As a result, a single high-resistance connection
anywhere in the ring will have almost no effect. That should do a more
reliable job of tying together all the ground connections for the different
pieces of equipment.


Almost right. The ring actually goes right back to the breaker box,
which is always located where the power enters the house. But the
effect is the same.

d

--
Pearce Consulting
http://www.pearce.uk.com

"Andy" wrote in message
...
I am in the UK.

I would like to take a stereo signal from the line-out of my stereo
(or TV) to the line-in of my PC.

The equipment is in different rooms and the audio cable would be 10
metres. It will be this type:
http://www.maplin.co.uk/images/full/130i0.jpg

I don't understand the technical side but is 10 metres so long that
it might cause audio problems with things like frequency response or
voltage/current levels and so on?

Will I need to get some higher specification audio cable to cover
that distance? I want to keep cost down.

I am using the exact same cable from Maplin, this is to go from my computer
to my stereo amp.

I would estimate it to be 10m-15m in length and I've had no problems with
noise.

sQuick..

On 19 Apr 2006, wrote:

mc spake thus:

I gather that you are in the UK (hence "ring" wiring
structure, which I like, instead of the American daisychain)
and that everything is in the same room. It should work fine.


So how does house wiring work in the UK? Is there more than one
grounding ("earthing") point? And how is this better?

(Here, the Merkin practice is to ground the "service
panel"--the box where the big wires come into the house--to a
single ground rod, with everything running downstream from
that.)

By the way, this brings up a strange experience I had recently
doing some wiring. I was working for a guy who owns two houses
right next to each other, and he wanted to run a cable TV
connection from one house to the other. I was about to connect
the cable in the attic of the house that was the source of the
signal when I got a little tingle. After grabbing a VOM, it
turned out that there was about a 20 volt difference between
the two cable grounds.

Mc doesn't understand ground loops. You can get them between two
boxes plugged into the same double socket.

Your tingle was because your equipment is not grounded, and is
perfectly normal.

Does your "perfectly normal" mean:

"there is no fault and no danger (until the ground is
actually needed and then will be a danger)"

On 19 Apr 2006, wrote:

"Andy" wrote in message
...
I am in the UK.

I would like to take a stereo signal from the line-out of my
stereo (or TV) to the line-in of my PC.

The equipment is in different rooms and the audio cable would
be 10 metres. It will be this type:
http://www.maplin.co.uk/images/full/130i0.jpg

I don't understand the technical side but is 10 metres so long
that it might cause audio problems with things like frequency
response or voltage/current levels and so on?

Will I need to get some higher specification audio cable to
cover that distance? I want to keep cost down.

I am using the exact same cable from Maplin, this is to go from
my computer to my stereo amp.

I would estimate it to be 10m-15m in length and I've had no
problems with noise.

sQuick..



Thanks to you and everyone else for the feedback. Seems it is
less of a problem than i was anticipating.

Actually my cable is not exactly the Maplin one I illustarted but
a very similar one.

"mc" wrote:
"Eiron" wrote in message
...

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Two boxes with 3-wire plugs?

Could you elaborate? I thought a ground loop was due to difference in
potential of the ground connections of 2 different pieces of equipment.

A "ground loop" is caused by having a common ground path for two
different signals. Current from each signal causes a voltage
drop, due to Ohmic losses, across the ground path for both
circuits. The effect is that each circuit affects the signal of
the other. Typically if one of those signals is 60 Hz power and
the other is something in the audio range, the audio signal will
then have a 60 Hz "buzz" on it.

Obviously, if the only ground path is through a common 3-wire
socket, yes it is possible for two boxes to have a ground loop.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

"Richard Crowley" wrote:
"David Nebenzahl" wrote ...
No, my tingle was because I was holding two cables strung
between two different houses, each grounded at its
end. Doesn't seem normal at all to me.

If they were each properly "grounded", you would NOT
have seen any voltage differential. BY DEFINITION.

(Or else the two houses were on differen planets. :-)

That is not true. Granted that the 20 Volt differential he
mentions in another article is high (for a residential area), it
is not at all uncommon.

What is uncommon though, is a person who can actually feel 20
Volts!

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

"mc" wrote:
"Richard Crowley" wrote in message
...
"David Nebenzahl" wrote ...
No, my tingle was because I was holding two cables strung between two
different houses, each grounded at its end. Doesn't seem normal at all to
me.

If they were each properly "grounded", you would NOT
have seen any voltage differential. BY DEFINITION.

I would almost bet that at least one of them wasn't really grounded (to the
earth).

Then there would have been no differential, and hence no voltage and no
tingling... ;-)

Second choice is that high voltage is being conducted directly into the
earth from some kind of unintended connection. A bad thing.

Not a bad thing, just a rather common thing in many industrial areas.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

On Wed, 19 Apr 2006 09:03:21 -0800, (Floyd L.
Davidson) wrote:

"mc" wrote:
"Eiron" wrote in message
...

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Two boxes with 3-wire plugs?

Could you elaborate? I thought a ground loop was due to difference in
potential of the ground connections of 2 different pieces of equipment.

A "ground loop" is caused by having a common ground path for two
different signals. Current from each signal causes a voltage
drop, due to Ohmic losses, across the ground path for both
circuits. The effect is that each circuit affects the signal of
the other. Typically if one of those signals is 60 Hz power and
the other is something in the audio range, the audio signal will
then have a 60 Hz "buzz" on it.

Obviously, if the only ground path is through a common 3-wire
socket, yes it is possible for two boxes to have a ground loop.

You got this backwards. A ground loop is caused by having two ground
paths for a single signal wire. A hum signal is induced into the
signal wire by means of a hum current flowing round that ground loop.
That current can be generated in either of two ways - a simple
potential difference between the two grounds, or alternatively
magnetic induction into the loop; generally the first will generate
the bigger signal.

d

--
Pearce Consulting
http://www.pearce.uk.com

(Don Pearce) wrote:
On Wed, 19 Apr 2006 07:26:25 -0700, "Richard Crowley"
wrote:

"Laurence Payne" wrote...
There'll probably be 3 phases in the street. houses, or
groups of houses will be allocated a single phase.

Not in the parts of the USA where I have lived (up and down
the west coast). They break up the 3 phases back at the main
road and supply only one of the phases to each street (or 2-3
streets depending on the load) It is not economical to run all
3 phases along residential (or even small business) areas.

So what do they do when somebody asks for three phase supply? Even a

The above does describe typical residential power distributionn.
However, anywhere that industrial power (i.e., 3 phase) is
available, there will in fact be all three phases available...

reasonably small business here in the UK might well do that if their
power needs are significant. The power companies here actually prefer
to supply businesses that way, particularly if they are also careful
about their power factor correction.

Same in the US.

Or are zoning laws in the States such that it is not possible to set
up a business in an otherwise residential area?

That might be, might not be... it would depend on local laws.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Don Pearce spake thus:

On Wed, 19 Apr 2006 07:26:25 -0700, "Richard Crowley"
wrote:

"Laurence Payne" wrote...

There'll probably be 3 phases in the street. houses, or
groups of houses will be allocated a single phase.

Not in the parts of the USA where I have lived (up and down
the west coast). They break up the 3 phases back at the main
road and supply only one of the phases to each street (or 2-3
streets depending on the load) It is not economical to run all
3 phases along residential (or even small business) areas.

So what do they do when somebody asks for three phase supply? Even a
reasonably small business here in the UK might well do that if their
power needs are significant. The power companies here actually prefer
to supply businesses that way, particularly if they are also careful
about their power factor correction.

Reread my earlier post above. In it I described the situation where a
business I once owned needed to have a power converter installed for
3-phase. This was in Berkeley, in a commercial district, not a
residential one, and I think it's pretty typical of the Bay Area in
general, probably the urban U.S for that matter. The power companies
don't supply 3-phase power even to commercial areas; if someone needs
it, they put in a converter. (We had a printing press that required it.)
Most commercial businesses don't need 3-phase power. Large industrial
customers do.

I think the converters can be shared, so if a couple or a few
neighboring businesses need 3-phase power, they can all use the one
converter.


--
Pierre, mon ami. Jetez encore un Scientologiste
dans le baquet d'acide.

- from a posting in alt.religion.scientology titled
"France recommends dissolving Scientologists"

On Wed, 19 Apr 2006 11:34:12 -0700, David Nebenzahl
wrote:

Don Pearce spake thus:

On Wed, 19 Apr 2006 07:26:25 -0700, "Richard Crowley"
wrote:

"Laurence Payne" wrote...

There'll probably be 3 phases in the street. houses, or
groups of houses will be allocated a single phase.

Not in the parts of the USA where I have lived (up and down
the west coast). They break up the 3 phases back at the main
road and supply only one of the phases to each street (or 2-3
streets depending on the load) It is not economical to run all
3 phases along residential (or even small business) areas.

So what do they do when somebody asks for three phase supply? Even a
reasonably small business here in the UK might well do that if their
power needs are significant. The power companies here actually prefer
to supply businesses that way, particularly if they are also careful
about their power factor correction.

Reread my earlier post above. In it I described the situation where a
business I once owned needed to have a power converter installed for
3-phase. This was in Berkeley, in a commercial district, not a
residential one, and I think it's pretty typical of the Bay Area in
general, probably the urban U.S for that matter. The power companies
don't supply 3-phase power even to commercial areas; if someone needs
it, they put in a converter. (We had a printing press that required it.)
Most commercial businesses don't need 3-phase power. Large industrial
customers do.

I think the converters can be shared, so if a couple or a few
neighboring businesses need 3-phase power, they can all use the one
converter.

I'm surprised. Just down the road from me there is a small engineering
company - they have a couple of mills, a few lathes and assorted other
machine tools. The power company didn't even ask - they just got three
phase, straight from the street outside.

d

--
Pearce Consulting
http://www.pearce.uk.com

(Don Pearce) wrote:
On Wed, 19 Apr 2006 09:03:21 -0800, (Floyd L.
Davidson) wrote:

"mc" wrote:
"Eiron" wrote in message
...

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Two boxes with 3-wire plugs?

Could you elaborate? I thought a ground loop was due to difference in
potential of the ground connections of 2 different pieces of equipment.

A "ground loop" is caused by having a common ground path for two
different signals. Current from each signal causes a voltage
drop, due to Ohmic losses, across the ground path for both
circuits. The effect is that each circuit affects the signal of
the other. Typically if one of those signals is 60 Hz power and
the other is something in the audio range, the audio signal will
then have a 60 Hz "buzz" on it.

Obviously, if the only ground path is through a common 3-wire
socket, yes it is possible for two boxes to have a ground loop.

You got this backwards.

Actually, what I said was *precisely* correct.

A ground loop is caused by having two ground
paths for a single signal wire.

Your language is a mess, but what you just said is *exactly* the
same thing. One wire is a common path...

A hum signal is induced into the
signal wire by means of a hum current flowing round that ground loop.

Wrong. There is no loop involved. It is current flowing on the
*common* portion that causes interaction.

That current can be generated in either of two ways - a simple
potential difference between the two grounds, or alternatively
magnetic induction into the loop; generally the first will generate
the bigger signal.

Get a book or two... and study what happens. Try drawing a diagram
of what you think is happening!

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

On Wed, 19 Apr 2006 11:23:24 -0800, (Floyd L.
Davidson) wrote:

(Don Pearce) wrote:
On Wed, 19 Apr 2006 09:03:21 -0800, (Floyd L.
Davidson) wrote:

"mc" wrote:
"Eiron" wrote in message
...

Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.

Two boxes with 3-wire plugs?

Could you elaborate? I thought a ground loop was due to difference in
potential of the ground connections of 2 different pieces of equipment.

A "ground loop" is caused by having a common ground path for two
different signals. Current from each signal causes a voltage
drop, due to Ohmic losses, across the ground path for both
circuits. The effect is that each circuit affects the signal of
the other. Typically if one of those signals is 60 Hz power and
the other is something in the audio range, the audio signal will
then have a 60 Hz "buzz" on it.

Obviously, if the only ground path is through a common 3-wire
socket, yes it is possible for two boxes to have a ground loop.

You got this backwards.

Actually, what I said was *precisely* correct.

Nonsense - you claim one ground path and two signals. It is one signal
and two ground paths - it is those two ground paths that form the
ground loop.

A ground loop is caused by having two ground
paths for a single signal wire.

Your language is a mess, but what you just said is *exactly* the
same thing. One wire is a common path...

No, my language is just fine, and it is the exact opposite of what you
said.

A hum signal is induced into the
signal wire by means of a hum current flowing round that ground loop.

Wrong. There is no loop involved. It is current flowing on the
*common* portion that causes interaction.

There is a loop involved. That is why it is called a ground loop. The
loop is necessary for the current to flow round and generate the emf
that appears on the signal wire.

That current can be generated in either of two ways - a simple
potential difference between the two grounds, or alternatively
magnetic induction into the loop; generally the first will generate
the bigger signal.

Get a book or two... and study what happens. Try drawing a diagram
of what you think is happening!

Thank you, I have designed a great deal of high precision measuring
equipment and I know exactly what signal paths are present in a ground
loop. And they aren't what you claim.

d

--
Pearce Consulting
http://www.pearce.uk.com

David Nebenzahl wrote:
Don Pearce spake thus:

On Wed, 19 Apr 2006 07:26:25 -0700, "Richard Crowley"
wrote:

"Laurence Payne" wrote...

There'll probably be 3 phases in the street. houses, or
groups of houses will be allocated a single phase.

Not in the parts of the USA where I have lived (up and down
the west coast). They break up the 3 phases back at the main
road and supply only one of the phases to each street (or 2-3
streets depending on the load) It is not economical to run all
3 phases along residential (or even small business) areas.
So what do they do when somebody asks for three phase supply?
Even a
reasonably small business here in the UK might well do that if their
power needs are significant. The power companies here actually prefer
to supply businesses that way, particularly if they are also careful
about their power factor correction.

Reread my earlier post above. In it I described the situation
where a business I once owned needed to have a power converter
installed for 3-phase. This was in Berkeley, in a commercial
district, not a residential one, and I think it's pretty typical
of the Bay Area in general, probably the urban U.S for that
matter. The power companies don't supply 3-phase power even to
commercial areas; if someone needs it, they put in a
converter. (We had a printing press that required it.) Most
commercial businesses don't need 3-phase power. Large industrial
customers do.

I think the converters can be shared, so if a couple or a few
neighboring businesses need 3-phase power, they can all use the
one converter.

What is a "converter"? I've never heard of anything described
that way.

Virtually all power is generated as 3-phase...

What you actually get merely depends on what the transformer
arrangement is. Single phase residential power is nothing other
than one phase from a 3 phase distribution system. All that is
required to have 3 phase power is *more wires*!

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

(Don Pearce) wrote:
On Wed, 19 Apr 2006 11:23:24 -0800, (Floyd L.
Davidson) wrote:
Actually, what I said was *precisely* correct.

Nonsense - you claim one ground path and two signals. It is one signal
and two ground paths - it is those two ground paths that form the
ground loop.

And I have it *precisely* correct. (Hint: I'm not guessing.)

If there were only one signal... what problem would there be????
The trouble is that one signal causes interference with another.
It does that because they share a common path. Ohmic losses across
that conductor affect *both* signals, even when caused by only one
of them. Bingo, that *is* the problem.

A ground loop is caused by having two ground
paths for a single signal wire.

Your language is a mess, but what you just said is *exactly* the
same thing. One wire is a common path...

No, my language is just fine, and it is the exact opposite of what you
said.

Two ground paths and one wire... does *not* make sense.
Signals have paths. Those paths can be wires. You can't have
two paths in one wire...

But the common "ground loop" is indeed caused by grounding a
single conductor at two points. That provides a common path
through the single wire... for *two* signals. One is the
"desired" signal, and the other is a current between the two
ground points.

A hum signal is induced into the
signal wire by means of a hum current flowing round that ground loop.

Wrong. There is no loop involved. It is current flowing on the
*common* portion that causes interaction.

There is a loop involved. That is why it is called a ground loop. The
loop is necessary for the current to flow round and generate the emf
that appears on the signal wire.

Try drawing a diagram of what you are describing.

That current can be generated in either of two ways - a simple
potential difference between the two grounds, or alternatively
magnetic induction into the loop; generally the first will generate
the bigger signal.

Get a book or two... and study what happens. Try drawing a diagram
of what you think is happening!

Thank you, I have designed a great deal of high precision measuring
equipment and I know exactly what signal paths are present in a ground
loop. And they aren't what you claim.

If you do know what it is, you certainly have a problem
describing it in terms that make sense. I'll vote for you
don't know...

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

mc wrote:
"Eiron" wrote in message
...


Mc doesn't understand ground loops. You can get them between two boxes
plugged into the same double socket.


Two boxes with 3-wire plugs?

Could you elaborate? I thought a ground loop was due to difference in
potential of the ground connections of 2 different pieces of equipment.

Remember the good old days when everything had a 3-core mains cable?
You could get a ground loop just plugging a tape recorder into an amp.
The bodger's solution was to disconnect the earth in the mains plug
and remember always to connect the audio cable to the amp before connecting
the power. Now everything has 2-core power leads so you get tingles.

--
Eiron

No good deed ever goes unpunished.

On Wed, 19 Apr 2006 11:46:44 -0800, (Floyd L.
Davidson) wrote:

(Don Pearce) wrote:
On Wed, 19 Apr 2006 11:23:24 -0800, (Floyd L.
Davidson) wrote:
Actually, what I said was *precisely* correct.

Nonsense - you claim one ground path and two signals. It is one signal
and two ground paths - it is those two ground paths that form the
ground loop.

And I have it *precisely* correct. (Hint: I'm not guessing.)

If there were only one signal... what problem would there be????
The trouble is that one signal causes interference with another.
It does that because they share a common path. Ohmic losses across
that conductor affect *both* signals, even when caused by only one
of them. Bingo, that *is* the problem.

So what are you saying here - that a mono signal can't suffer a ground
loop? Stereo is the minimum that can show the problem?

You only need one signal. Here's a hint as to where you may be going
wrong. Signal is the term used to describe the wanted stuff. The rest
isn't signal - it is hum.

A ground loop is caused by having two ground
paths for a single signal wire.

Your language is a mess, but what you just said is *exactly* the
same thing. One wire is a common path...

No, my language is just fine, and it is the exact opposite of what you
said.

Two ground paths and one wire... does *not* make sense.
Signals have paths. Those paths can be wires. You can't have
two paths in one wire...

Of course it makes sense. The commonest scenario for two ground paths
is that one is the outer of the coax, and the other is a pair of
ground wires in the mains leads, meeting at the mains ground. The
single signal wire is the inner of the coax. This just isn't that hard
to understand.

But the common "ground loop" is indeed caused by grounding a
single conductor at two points. That provides a common path
through the single wire... for *two* signals. One is the
"desired" signal, and the other is a current between the two
ground points.


No it doesn't. It means that the ground is connected via two separate
paths - you need those two separate paths to form the loop.

A hum signal is induced into the
signal wire by means of a hum current flowing round that ground loop.

Wrong. There is no loop involved. It is current flowing on the
*common* portion that causes interaction.

There is a loop involved. That is why it is called a ground loop. The
loop is necessary for the current to flow round and generate the emf
that appears on the signal wire.

Try drawing a diagram of what you are describing.

Done. You can find it here http://81.174.169.10/

That current can be generated in either of two ways - a simple
potential difference between the two grounds, or alternatively
magnetic induction into the loop; generally the first will generate
the bigger signal.

Get a book or two... and study what happens. Try drawing a diagram
of what you think is happening!

Thank you, I have designed a great deal of high precision measuring
equipment and I know exactly what signal paths are present in a ground
loop. And they aren't what you claim.

If you do know what it is, you certainly have a problem
describing it in terms that make sense. I'll vote for you
don't know...

No, I think I have described what is going on perfectly - I suspect
the confusion is at your end. It may be simply a semantic confusion
over what constitutes the signal.

d

--
Pearce Consulting
http://www.pearce.uk.com

Andy wrote:
On 19 Apr 2006, wrote:


mc spake thus:


I gather that you are in the UK (hence "ring" wiring
structure, which I like, instead of the American daisychain)
and that everything is in the same room. It should work fine.


So how does house wiring work in the UK? Is there more than one
grounding ("earthing") point? And how is this better?

(Here, the Merkin practice is to ground the "service
panel"--the box where the big wires come into the house--to a
single ground rod, with everything running downstream from
that.)

By the way, this brings up a strange experience I had recently
doing some wiring. I was working for a guy who owns two houses
right next to each other, and he wanted to run a cable TV
connection from one house to the other. I was about to connect
the cable in the attic of the house that was the source of the
signal when I got a little tingle. After grabbing a VOM, it
turned out that there was about a 20 volt difference between
the two cable grounds.

Mc doesn't understand ground loops. You can get them between two
boxes plugged into the same double socket.

Your tingle was because your equipment is not grounded, and is
perfectly normal.


Does your "perfectly normal" mean:

"there is no fault and no danger (until the ground is
actually needed and then will be a danger)"

No. It's normal and legal to have a load of double-insulated equipment
connected together so the signal ground is floating at roughly half
mains voltage and can deliver several mA. It's dangerous, in my opinion.

In the UK, with 240v mains, and adjacent houses on different phases,
you might have 220v between the two cables in the attic.

And you can't feel 20v AC unless one end is on your tongue. I just tried it. :-)

--
Eiron

No good deed ever goes unpunished.

Floyd L. Davidson spake thus:

David Nebenzahl wrote:

Don Pearce spake thus:

On Wed, 19 Apr 2006 07:26:25 -0700, "Richard Crowley"
wrote:

"Laurence Payne" wrote...

There'll probably be 3 phases in the street. houses, or
groups of houses will be allocated a single phase.

Not in the parts of the USA where I have lived (up and down
the west coast). They break up the 3 phases back at the main
road and supply only one of the phases to each street (or 2-3
streets depending on the load) It is not economical to run all
3 phases along residential (or even small business) areas.

So what do they do when somebody asks for three phase supply?
Even a
reasonably small business here in the UK might well do that if their
power needs are significant. The power companies here actually prefer
to supply businesses that way, particularly if they are also careful
about their power factor correction.

Reread my earlier post above. In it I described the situation
where a business I once owned needed to have a power converter
installed for 3-phase. This was in Berkeley, in a commercial
district, not a residential one, and I think it's pretty typical
of the Bay Area in general, probably the urban U.S for that
matter. The power companies don't supply 3-phase power even to
commercial areas; if someone needs it, they put in a
converter. (We had a printing press that required it.) Most
commercial businesses don't need 3-phase power. Large industrial
customers do.

I think the converters can be shared, so if a couple or a few
neighboring businesses need 3-phase power, they can all use the
one converter.

What is a "converter"? I've never heard of anything described
that way.

It's a device--a big, honking piece of electromagnetic equipment--that
generates 3-phase power from 2-phase power. In this case, it sits in an
underground vault beneath the sidewalk, covered by one of them metal plates.

Virtually all power is generated as 3-phase...

Nope.

What you actually get merely depends on what the transformer
arrangement is. Single phase residential power is nothing other
than one phase from a 3 phase distribution system. All that is
required to have 3 phase power is *more wires*!

Apparently not. If you don't believe me, ask PG&E (Pacific Greed and
Extortion, as they're known around here). They don't run all 3 wires as
part of their normal power distribution.

I know this thing exists, because I saw the crews working on the damn
thing in front of my shop when it malfunctioned and the press stopped
working.


--
Pierre, mon ami. Jetez encore un Scientologiste
dans le baquet d'acide.

- from a posting in alt.religion.scientology titled
"France recommends dissolving Scientologists"

On Wed, 19 Apr 2006 13:44:48 -0700, David Nebenzahl
wrote:

Virtually all power is generated as 3-phase...

Nope.

What you actually get merely depends on what the transformer
arrangement is. Single phase residential power is nothing other
than one phase from a 3 phase distribution system. All that is
required to have 3 phase power is *more wires*!

Apparently not. If you don't believe me, ask PG&E (Pacific Greed and
Extortion, as they're known around here). They don't run all 3 wires as
part of their normal power distribution.

I know this thing exists, because I saw the crews working on the damn
thing in front of my shop when it malfunctioned and the press stopped
working.


I'm stunned. This is the first time I've ever heard of power being
generated as anything other than three phase. Apart from anything
else, single phase is mega wasteful of copper.

d

--
Pearce Consulting
http://www.pearce.uk.com

Eiron spake thus:

And you can't feel 20v AC unless one end is on your tongue. I just tried
it. :-)

Some of us may be more sensitive than others. It's a subjective thing,
after all. Believe me, I felt *something*. Being the paranoid
electrician type, I let go of that sucker in a hurry! VOM showed ~20v.
(Dunno whether AC or DC; I'm assuming AC.)


--
Pierre, mon ami. Jetez encore un Scientologiste
dans le baquet d'acide.

- from a posting in alt.religion.scientology titled
"France recommends dissolving Scientologists"