ground-loop problems

[William Sommerwerck]

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:50741e26d5dave@davenoise.co.uk...

In article <h2g34j$527$1@news.eternal-september.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:

Er, either they're fitted with balanced connectors or they're not. To
modify an unbalanced unit isn't a trivial matter. Involves either using
expensive transformers at either end of the line or incorporating new
electronics. You don't just buy a new cable. ;-)

Sure you do. Almost all "good" home-cinema (as well as middle-to-
high-end audio) equipment has both balanced and unbalanced ins
and outs. (My Parasound controller does. I use the unbalanced
outputs to feed a Pioneer quadrascope.)

Total overkill. Balanced audio is only needed for very long runs or in
very hostile environments -- not found in the home. Are your aerial
and video connections balanced?

We've been through this before, and I'm not going to keep arguing. Most
equipment these days has balanced connections. It's ridiculous not to spend
a little more for balanced cables.

 

[William Sommerwerck]

Wow. Thanks for all that useful stuff. Really.

 

[Dave Plowman (News)]

In article <h2i7dl$cqc$1@news.eternal-september.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:

Total overkill. Balanced audio is only needed for very long runs or in
very hostile environments -- not found in the home. Are your aerial
and video connections balanced?

We've been through this before, and I'm not going to keep arguing. Most
equipment these days has balanced connections.

Domestic? It doesn't. It adds cost for no reason.

It's ridiculous not to spend a little more for balanced cables.

All a cable needs to do is connect things together. Properly. And you
simply don't need to use balanced in a domestic environment.

--
*Who is this General Failure chap anyway - and why is he reading my HD? *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[cjt]

Dave Plowman (News) wrote:

In article <h2i7dl$cqc$1@news.eternal-september.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:

Total overkill. Balanced audio is only needed for very long runs or in
very hostile environments -- not found in the home. Are your aerial
and video connections balanced?


We've been through this before, and I'm not going to keep arguing. Most
equipment these days has balanced connections.


Domestic? It doesn't. It adds cost for no reason.


It's ridiculous not to spend a little more for balanced cables.


All a cable needs to do is connect things together. Properly. And you
simply don't need to use balanced in a domestic environment.

It doesn't hurt. The incremental cost is small.

 

[David Lesher]

"Dave Plowman (News)" <dave@davenoise.co.uk> writes:

Do you routinely have different phases running audio equipment in the
same room in a house in the US? This smacks to me of bad practice and
isn't allowed in the UK.

The UK has very different wiring than the US.

Here, a standard circuit is 120v/20A or 2400 watts [at unity PF...]

In the UK; ring wiring supplies 240v/30A, or 7200 watts. Plugs
have internal fuses based on the device.

(The US may well have a 240V/20A outlet for an air conditioner;
where it's 120-N-120.)



--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[Dave Plowman (News)]

In article <h15mhh$ip4$1@reader1.panix.com>,
David Lesher <wb8foz@panix.com> wrote:

Do you routinely have different phases running audio equipment in the
same room in a house in the US? This smacks to me of bad practice and
isn't allowed in the UK.

The UK has very different wiring than the US.

Yes - I understand that.

Indeed. So one circuit should be adequate for feeding any 'portable'
appliances in a room? Excluding heating etc. Not many domestic audio
systems will need a 2400 watt supply. Not even mine. ;-)

In the UK; ring wiring supplies 240v/30A, or 7200 watts. Plugs
have internal fuses based on the device.

32 amp is the standard these days.

(The US may well have a 240V/20A outlet for an air conditioner;
where it's 120-N-120.)

So a local centre tap transformer gives you the 110v from a 220 ish
supply? To me it would make sense to not have both sides of that
transformer output in one room - why present an additional hazard if not
necessary?

--
*INDECISION is the key to FLEXIBILITY *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[AZ Nomad]

On Mon, 15 Jun 2009 18:11:44 +0100, Dave Plowman (News) <dave@davenoise.co.uk> wrote:

In article <h15mhh$ip4$1@reader1.panix.com>,
David Lesher <wb8foz@panix.com> wrote:
Do you routinely have different phases running audio equipment in the
same room in a house in the US? This smacks to me of bad practice and
isn't allowed in the UK.

The UK has very different wiring than the US.

Yes - I understand that.

Here, a standard circuit is 120v/20A or 2400 watts [at unity PF...]

Indeed. So one circuit should be adequate for feeding any 'portable'
appliances in a room? Excluding heating etc. Not many domestic audio
systems will need a 2400 watt supply. Not even mine. ;-)

In the UK; ring wiring supplies 240v/30A, or 7200 watts. Plugs
have internal fuses based on the device.

32 amp is the standard these days.

(The US may well have a 240V/20A outlet for an air conditioner;
where it's 120-N-120.)

So a local centre tap transformer gives you the 110v from a 220 ish
supply? To me it would make sense to not have both sides of that
transformer output in one room - why present an additional hazard if not
necessary?

Why would it matter? When is there a situation when the hot from
one outlet is connected to the hot from another outlet?1

Are you talking about a power company transformer, typically sitting
atop a telephone pole?
There certainly isn't any CT transformer inside any residence as
both legs of the 220 two phase are fed to the household.

 

[Michael A. Terrell]

"Dave Plowman (News)" wrote:

In article <h15mhh$ip4$1@reader1.panix.com>,
David Lesher <wb8foz@panix.com> wrote:
Do you routinely have different phases running audio equipment in the
same room in a house in the US? This smacks to me of bad practice and
isn't allowed in the UK.

The UK has very different wiring than the US.

Yes - I understand that.

Here, a standard circuit is 120v/20A or 2400 watts [at unity PF...]

Indeed. So one circuit should be adequate for feeding any 'portable'
appliances in a room? Excluding heating etc. Not many domestic audio
systems will need a 2400 watt supply. Not even mine. ;-)

In the UK; ring wiring supplies 240v/30A, or 7200 watts. Plugs
have internal fuses based on the device.

32 amp is the standard these days.

(The US may well have a 240V/20A outlet for an air conditioner;
where it's 120-N-120.)

So a local centre tap transformer gives you the 110v from a 220 ish
supply? To me it would make sense to not have both sides of that
transformer output in one room - why present an additional hazard if not
necessary?

Try 120-0-120 for 240 VAC. You usually only see 220 in and older
area that needs upgrading. 130 V light bulbs are common, too. My line
voltage runs around 125-0-125 most of the time.


What hazard? The lighting circuits are supposed to be on different
circuits than the outlets. Some family rooms, or 'Great Rooms' can have
three or four 20 amp circuits for outlets. Even if they are all on the
same phase, the different loads and wire lengths vary the voltage drop
in the return leg, no matter if it is a 120 or 240 volt circuit. Take
your meter and measure the difference between the neutral and ground on
your outlets. If nothing is in use, they are equal. A moderate load
will cause the voltage on the neutral to rise. Depending on where you
are on that circuit, you will see different voltages. Even with your
ring circuits.

The US philosophy is to only trip breaker in a fault condition and
that means extra capacity.



--
You can't have a sense of humor, if you have no sense!

 

[David Nebenzahl]

On 6/15/2009 12:13 PM Michael A. Terrell spake thus:

The US philosophy is to only trip breaker in a fault condition and
that means extra capacity.

So what is the UK philosophy in this regard?


--
Found--the gene that causes belief in genetic determinism

 

[Dave Plowman (News)]

In article <slrnh3d10s.atd.aznomad.3@ip70-176-155-130.ph.ph.cox.net>,
AZ Nomad <aznomad.3@PremoveOBthisOX.COM> wrote:

So a local centre tap transformer gives you the 110v from a 220 ish
supply? To me it would make sense to not have both sides of that
transformer output in one room - why present an additional hazard if not
necessary?

Why would it matter? When is there a situation when the hot from
one outlet is connected to the hot from another outlet?1

Fault condition - you could have 220v between two surfaces. And silly
because there's no need.

--
*How can I miss you if you won't go away?

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Dave Plowman (News)]

In article <vbydnVs4F6XKAKvXnZ2dnUVZ_vCdnZ2d@earthlink.com>,
Michael A. Terrell <mike.terrell@earthlink.net> wrote:

So a local centre tap transformer gives you the 110v from a 220 ish
supply? To me it would make sense to not have both sides of that
transformer output in one room - why present an additional hazard if
not necessary?

Try 120-0-120 for 240 VAC. You usually only see 220 in and older
area that needs upgrading. 130 V light bulbs are common, too. My line
voltage runs around 125-0-125 most of the time.

What hazard? The lighting circuits are supposed to be on different
circuits than the outlets. Some family rooms, or 'Great Rooms' can have
three or four 20 amp circuits for outlets. Even if they are all on the
same phase, the different loads and wire lengths vary the voltage drop
in the return leg, no matter if it is a 120 or 240 volt circuit. Take
your meter and measure the difference between the neutral and ground on
your outlets. If nothing is in use, they are equal. A moderate load
will cause the voltage on the neutral to rise. Depending on where you
are on that circuit, you will see different voltages. Even with your
ring circuits.

You're totally missing the point. 110/120 v is generally thought to be
rather safer electrocution wise than 240 - it's used on UK building sites.
Although via an isolating transformer so floating and therefore no
reference to earth. If you have two phase 120v in one room under certain
fault conditions you could have the full 240v risk. In the UK make that
415v. And not allowed, on sockets. Heating - hard wired - would be ok.
Why would you want 'three or four' 20 amp circuits in a 'family' room?

The US philosophy is to only trip breaker in a fault condition and
that means extra capacity.

--
*Taxation WITH representation ain't much fun, either.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[AZ Nomad]

On Mon, 15 Jun 2009 23:58:08 +0100, Dave Plowman (News) <dave@davenoise.co.uk> wrote:

In article <slrnh3d10s.atd.aznomad.3@ip70-176-155-130.ph.ph.cox.net>,
AZ Nomad <aznomad.3@PremoveOBthisOX.COM> wrote:
So a local centre tap transformer gives you the 110v from a 220 ish
supply? To me it would make sense to not have both sides of that
transformer output in one room - why present an additional hazard if not
necessary?

Why would it matter? When is there a situation when the hot from
one outlet is connected to the hot from another outlet?1

Fault condition - you could have 220v between two surfaces. And silly
because there's no need.

No you wouldn't. You'd have 0 V between two chassis connected to the
ground. Having one device with it's ground connected to the hot is
rare. Having two such devices plugged in different outlets
yet within arm's grasp of each other is fantasy.

 

[David Lesher]

"Dave Plowman (News)" <dave@davenoise.co.uk> writes:

Indeed. So one circuit should be adequate for feeding any 'portable'
appliances in a room? Excluding heating etc. Not many domestic audio
systems will need a 2400 watt supply. Not even mine. ;-)

You clearly don't know the folks I do...

32 amp is the standard these days.

Thanks to the EU...

(The US may well have a 240V/20A outlet for an air conditioner;
where it's 120-N-120.)

So a local centre tap transformer gives you the 110v from a 220 ish
supply? To me it would make sense to not have both sides of that
transformer output in one room - why present an additional hazard if not
necessary?

The local transformer is on a pole outside, or a pad. The breaker panel
is split; half the loads on each leg. Big loads: stove, water heater,
whole house airconditioning, dryer are fed with 240V.

Why would you want 'three or four' 20 amp circuits in a 'family' room?

Why would anyone drive down the wrong side of the road, or use Whitworth
threads? It's not usual for a large room to have multiple circuits. If we
had a 7500 watt scheme, one would do, I suspect.
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433