Re: Ground Rod For House ?
- From: "Pop" <nobody@xxxxxxxxxxxxxxxxxxx>
- Date: Sun, 1 Jan 2006 11:59:52 -0500
"w_tom" <w_tom1@xxxxxxxxxxx> wrote in message
news:43B74219.8B0322EE@xxxxxxxxxxxxxx
: An example demonstrates the earthing problem. A 12 AWG wire
: from wall receptacle maybe 50 feet back to mains box has less
: than 0.2 ohms resistance.
That same wire would have something
: like 120 ohms impedance.
At what frequency, and what are the approx reactive components?
See, this is the kind of non-information I'm talking about.
Lets say a tiny 100 amp transient
: seeks earth ground via that 50 foot wire. Therefore a wall
: receptacle - and adjacent electronics - will be at something
: less than 12,000 volts.
Time? Duration? Energy? What is the power in each component?
Think about it.
Will that transient seek earth via
: that safety ground wire? Of course not. It will also seek
: other and destructive paths via adjacent electronics.
No, ALL freqs/rise/falls will not seek the same path. Think
about it.
:
: Wire length is but one reason why a wall receptacle safety
: ground is not sufficient as earth ground. Also explains why
: plug-in protectors are so ineffective.
I don't recall anyone saying that was the case. Did they?
:
: Essential to minimizing wire impedance are wire length, no
: sharp bends,
My gosh, what are you doing, applying field theory and
waveguides? This is exactly what makes your possibly well
intentioned information so useless. I'm surprised you left out
the skin effect and a few other nice nouns you could have dropped
in there.
and other characteristics cited previously. Also
: important is a concept cited by Bud--
: > Clamping all incoming wires to the same the same ground
: > reference is the best way I know to protect electronics. ...
Where did anyone claim it wasn't? The "best" wasn't the
question; sufficient or acceptable were the words, IIRC.
: The quality of a service entrance protector is only as
: effective as its earth ground which is why distance to that
: earthing is so critical and why single point earthing is
: essential. That means the 6 AWG wire does not go up over a
: foundation and then down to an earth ground rod. That wire
: goes through foundation somewhere just above the ground rod so
: that wire distance is shorter with sharp bends eliminated.
Uhh, the sharp bends problem isn't for impedance or electrical
considerations; it's physical properties related. Think about
what you're saying.
: Also important is that earthing wire remain separated from
: other non-earthing wires to avoid induced transients.
I don't think that was any part of the subject; true but not
directly relevant.
:
: Yes, lower resistance does help which is why high
: reliability facilities such as electric substations expand
: their earth ground to also lower resistance. It is also why
: earthing should be planned when the footing are poured.
: Equipotential being another aspect of superior earthing.
Superior earthing: What's that go to do with anything?
Completely irrelevant to the subject matter.
:
: Unfortunately we still don't build as if the transistor
: exists. We still do earthing as an afterthought. Effective
: earthing addresses concepts in excess of that performed by
: conventional household earthing. Equipotential being a
: concept of transistor protection that is not as essential to
: human protection. If we built buildings for effective
: transistor protection, then Ufer grounds would be routine; and
: not some afterthought to supplement water pipe ground such as
: ground rods. Even water pipe would enter a building adjacent
: to all other utilities to contribute to transistor safety.
More irrelevance; no point to the entire para.
:
: Even NEC requires all incoming electrical utilities be
: earthed to a common point for human safety - a problem still
: found even in some new homes.
"Even NEC"?
....
More attempts at double-speak and name dropping clipped.
:
: Again, to answer the original poster's question - water pipe
: earthing alone is no longer sufficient to meet code. Upgrade
: to accomplish more than just meet code. Transistor protection
: is only as effective as a building's earth ground.
To take your bent for a moment, a "transistor" is defined as an
e-b-c junction with physical leads attached. Semiconductor
technology does indeed use the concept of transistors within
chips et al for analogic discussion, but they are not transistors
unless, like you, a person wished to take the word apart into its
components, and work from there.
It's also possible, still in your realm of fuzziness, to build
a computer system with NO earth reference, but with controlled
references, which will operate perfectly. I used to use such a
system daily in my routine daily work for many years.
And BTW, resistance IS a component of Impedance. If you wish
to use the terms interchangeably, you need to add the words pure
and reactance to your talk.
Don't be a blatherskite.
:
: Bud-- wrote:
: > As I said protector blocks for cable and TV should be
immediately
: > adjacent to the panel so all wiring is clamped to the same
ground
: > reference. You don't explain how a ground rod would help in
this
: > instance. Adding a ground rod near the FAX is not going to
provide
: > a low impedance to keep the ground reference for the FAX the
same
: > as the incoming neutral.
: > ...
: >
: > Incoming utilities listed have to have protector blocks near
the power
: > panel to get a common grounding reference.
: >
: > How does a 10 foot wire to a high resistance ground rod
provide a lower
: > ground impedance than a grounding electrode conductor and
water pipe?
: > This is cental to your arguments. Perhaps you could explain
and also
: > provide some citations that support your view.
: >
: > For a 500A service the conductor to a ground rod has to be
#6. The
: > conductor to a water pipe has to be 2/0 - 3.5 x the area. How
come?
: > Surges include high frequency components for which impedance
is
: > important. Grounding electrode conductor and water pipe has
one
: > function of limiting surges.
: >
: >> Another problem with using a cold water pipe as an earth
: >> ground connection - code wants each utility to be earthed
less
: >> than 20 feet to the common point.
: >
: > Cite the code.
: > ...
: >
: > Clamping all incoming wires to the same the same ground
reference
: > is the best way I know to protect electronics. That requires
the
: > protector blocks to be near the electrical panel. (More
properly
: > thay have to be near each other.) That is likely a lot more
: > important than resistance or impedance to ground. If all
wiring
: > was clamped to the same reference with no ground connection
could
: > electronics see a difference.
: >
: > > Gfretwell has posted how homes are now being built so
as to
: > > provide superior transistor safety in pictures at:
: > > http://members.aol.com/gfretwell/ufer.jpg
: > >
: > This is a concrete encased electrode which I said is probably
the second
: > best electrode (after water pipes). It is one of 3 electrodes
that must
: > be included in a ground system, if present. (The other 2 are
water pipe
: > and building steel, which a home doesn't have.) Not included:
ground rod.
: >
: > > Another also demonstrates better earthing. None of this
: > > would be required if city water pipe was sufficient as
earth
: > > ground for transistor safety:
: > > http://www.knology.net/~res0958z/
: > >
: > Most of us don't put 55 foot high lightning rods in our back
yard. Not
: > particualrly relevant.
: >
: > -------------
: > With regard to: Bud-- does not even quote code to justify his
post. You
: > do not understand why water pipes are required to have a
SUPPLEMENTAL
: > electrode and don't listen to people who do understand. Since
arguing
: > the code is pointles, I tried Physics - ground resistance.
That doesn't
: > seem to work either.
: >
: > bud--
.
- References:
- Re: Ground Rod For House ?
- From: Bud--
- Re: Ground Rod For House ?
- From: w_tom
- Re: Ground Rod For House ?
- Prev by Date: Re: ok to move refrigerator in workshop ?
- Next by Date: Re: Mold odor on carpet.
- Previous by thread: Re: Ground Rod For House ?
- Next by thread: Re: Ground Rod For House ?
- Index(es):
Relevant Pages
|
Loading
