"Trevor Wilson"


**AFAIK, the US system is fundamentally different to ours.


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

See here under the heading "Regulations".

http://en.wikipedia.org/wiki/Earthing_system

The MEN system used here in Australia seems to be unique.

See last para on same page.


...... Phil

Phil Allison wrote:
"Trevor Wilson"


**AFAIK, the US system is fundamentally different to ours.


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

See here under the heading "Regulations".

http://en.wikipedia.org/wiki/Earthing_system

The MEN system used here in Australia seems to be unique.

See last para on same page.

**Interesting. I'd have thunk that some places in Europe might employ a
similar system. Guess not. Ever since I ran across my first US audio product
with a high value resistor to chassis from (allegedly) Neutral, I realised
that the US system was highly flawed.


--
Trevor Wilson
www.rageaudio.com.au

Phil Allison wrote:
"Trevor Wilson"

**AFAIK, the US system is fundamentally different to ours.

** 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).

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

See here under the heading "Regulations".

http://en.wikipedia.org/wiki/Earthing_system

The MEN system used here in Australia seems to be unique.

See last para on same page.

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.

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 am a Canadian who was born and raised in The Netherlands. I live on
Planet Earth on a spot of land called Canada. We have noisy neighbours.

- harvested from Usenet

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*. :

On Nov 23, 6:36*pm, "Phil Allison" wrote:
"Trevor Wilson"



**AFAIK, the US system is fundamentally different to ours.

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

See here under the heading "Regulations".

http://en.wikipedia.org/wiki/Earthing_system

The MEN system used here in Australia seems to be unique.

See last para on same page.

..... *Phil

Rubbish. In most of Canada, it is manditory that the neutral be bonded
to earth at only ONE point, the service entrance switch enclosure.
From that point an earth conductor is connected to 2 ground rods and
to any metallic piping system(s).
Neutral failure is a not uncommon problem especially with overhead
aluminum 'triplex' service drops. A seagull deficates on the bare
aluminum neutral and it soon rots off leaving an open neutral
condition.
Ground rod to earth resistances of 5 ohms are not uncommon, so a 10A
unbalance between 'phases' could give a 50V offset of the neutral.

Neil S.