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Grounding

S

Simon Cussonnet

Jan 1, 1970
0
If you wanna get electrocuted it's your own right but make sure anyone isn't
using the same equipment.
I can't see the reason why you posted a question here since you're totally
convinced you're right and highly reluctant to any explanation.

I consider it's TROLL and drop your messages.
 
N

NSM

Jan 1, 1970
0
| If you wanna get electrocuted it's your own right but make sure anyone
isn't
| using the same equipment.
| I can't see the reason why you posted a question here since you're totally
| convinced you're right and highly reluctant to any explanation.
|
| I consider it's TROLL and drop your messages.

It's occurred to me that he's a troll, but he might just be criminally
stupid. There are plenty of people like that around - many of them working
as building contractors.

N
 
G

Graham

Jan 1, 1970
0
| If you look inside some power panels the white neutral is connected to the
| same terminal block as the green ground wires.
| What's the diff?

The difference is that it violates code and can result in your insurance
being voided in case of fire or accident. You may also be liable for death
or injury to other persons or loss of property.

This is called a multiple earthed (grounded) neutral system. It is carefully
designed to provide maximum safety for persons and property. The rules are
not arbitrary, not pointless, they are there for a reason. Ask 100
electricians - or 100,000 - and they will all tell you what you are
suggesting is wrong, dangerous and stupid. The neutral is grounded in very
specific places according to very specific rules.

I am a registered electrician as well as an electronics technician (in more
than one country) and I understand this system as well as anyone. You have
been told not to try this and given several reasons why. You have also been
told the right way to proceed. Believe those who advise you - they are
correct. Ask your local electrical inspector if you don't believe us.

If you insist on this foolish procedure, I suggest you practice first by
checking the level of gas in your tank with a lighted match.

NM


The OP simply posed an academic question; I see no suggestion that he
intends to tamper with his installation.

His arguments are clearly intended to evoke a response so he can understand
the situation better.

Isn't that the best way of learning?

You are being a bit hard on him.

Now shake hands and say sorry.


Graham.
 
N

NSM

Jan 1, 1970
0
| The OP simply posed an academic question; I see no suggestion that he
| intends to tamper with his installation.
|
| His arguments are clearly intended to evoke a response so he can
understand
| the situation better.
|
| Isn't that the best way of learning?
|
| You are being a bit hard on him.
|
| Now shake hands and say sorry.

"If you have a 2 wire house electrical system what's the difference between
a 3 wire system and installing a 3 wire plug and jumping the ground pin to
the white return line. I see no electrical difference between that and
running a green wire all the way to the box and connecting it to the same
place as the return line ground. If you know what I mean."

Sounds like he was planning to rewire his house into a fool killer system to
me.

N
 
F

Franc Zabkar

Jan 1, 1970
0
| If you wanna get electrocuted it's your own right but make sure anyone
isn't
| using the same equipment.
| I can't see the reason why you posted a question here since you're totally
| convinced you're right and highly reluctant to any explanation.
|
| I consider it's TROLL and drop your messages.

It's occurred to me that he's a troll, but he might just be criminally
stupid. There are plenty of people like that around - many of them working
as building contractors.

AFAICS, the OP is not stupid, only ignorant of this particular
subject. IMO the question was a fair one that deserved an explanation
a little less condescending than "don't do it because it's not safe".
In fact, I'm betting that the majority of electricians don't
understand why they do things a certain way, they just blindly follow
rules.


- Franc Zabkar
 
W

w_tom

Jan 1, 1970
0
Appreciate that wire is not electrically same at both
ends. Wire is not a perfect conductor. Wire is treated as if
it was another electronic component. How much difference
exists between two ends of a wire is determined by
characteristics of the current in that wire - ie. amperes,
open circuit driving voltage, frequency, harmonics, etc. Most
of this will be well beyond the scope of this discussion.

But human safety demands that any electrical appliance be
connected as best as possible to the safety ground inside
breaker box panel (point where safety ground wires, white
neutral wire, utility neutral wire, and earth ground wire all
meet). The only wire that can make such a connection is one
that is not carrying any current - the bare ground wire. Even
though the white neutral wire also meets at that point, the
white wire has significant differences at both ends - because
white wire is carrying up to 20 amps current.

Others have provided examples of why the white wire and bare
safety ground wire are completely different wires at the wall
receptacle. Bottom line - the white wire and bare safety
ground wire are only same where both meet at the breaker box
safety ground.

You may even be able to see this difference with a digital
volt meter. When AC outlet powers a significant load (ie
toaster or steam iron), then a voltage difference should exist
between white neutral wire and bare copper safety ground wire
at that wall receptacle.

Are white neutral and bare copper safety wires properly
isolated? Breaker box GFCIs tend to trip (cut off power) when
bare copper white is shorted (connected) to white neutral wire
anywhere but inside the breaker box. Just another in a long
list of examples that demonstrate why white neutral and bare
copper safety ground wire are electrically different. Why one
wire cannot perform both functions.
 
S

Sam Goldwasser

Jan 1, 1970
0
w_tom said:
Appreciate that wire is not electrically same at both
ends. Wire is not a perfect conductor. Wire is treated as if
it was another electronic component. How much difference
exists between two ends of a wire is determined by
characteristics of the current in that wire - ie. amperes,
open circuit driving voltage, frequency, harmonics, etc. Most
of this will be well beyond the scope of this discussion.

But human safety demands that any electrical appliance be
connected as best as possible to the safety ground inside
breaker box panel (point where safety ground wires, white
neutral wire, utility neutral wire, and earth ground wire all
meet). The only wire that can make such a connection is one
that is not carrying any current - the bare ground wire. Even
though the white neutral wire also meets at that point, the
white wire has significant differences at both ends - because
white wire is carrying up to 20 amps current.

Others have provided examples of why the white wire and bare
safety ground wire are completely different wires at the wall
receptacle. Bottom line - the white wire and bare safety
ground wire are only same where both meet at the breaker box
safety ground.

You may even be able to see this difference with a digital
volt meter. When AC outlet powers a significant load (ie
toaster or steam iron), then a voltage difference should exist
between white neutral wire and bare copper safety ground wire
at that wall receptacle.

Are white neutral and bare copper safety wires properly
isolated? Breaker box GFCIs tend to trip (cut off power) when
bare copper white is shorted (connected) to white neutral wire
anywhere but inside the breaker box. Just another in a long
list of examples that demonstrate why white neutral and bare
copper safety ground wire are electrically different. Why one
wire cannot perform both functions.

It's more fundamental than this. Even if the wires were made of
superconductors, the rules would be equally valid for safety.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
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traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header is ignored.
To contact me, please use the feedback form on the S.E.R FAQ Web sites.
 
R

Rodney Kelp

Jan 1, 1970
0
Ok, For those who worry, I am NOT wiring a house like this. This is only
theoretical.
So from what you say I see that the short jumper, on a 3 wire outlet,
from the green case ground post to the silver white neutral post has the
same potential as the bare copper safety wire has from the green case ground
post to the neutral binding posts in the breaker box panel.. Barring all
possible disasters Is there any electrical difference that the outlet sees
where you plug things in?
If the outlet is drawing 20 amps then isn't it felt at the breaker box paned
neutral connection where the equipment ground is connected?
As a matter of fact isn't the bare copper safety wire seeing the entire
house current at that neurtal connection in the breaker box panel at the
outlet's safety ground?
 
G

Graham

Jan 1, 1970
0
Appreciate that wire is not electrically same at both
ends. Wire is not a perfect conductor. Wire is treated as if
it was another electronic component. How much difference
exists between two ends of a wire is determined by
characteristics of the current in that wire - ie. amperes,
open circuit driving voltage, frequency, harmonics, etc. Most
of this will be well beyond the scope of this discussion.

But human safety demands that any electrical appliance be
connected as best as possible to the safety ground inside
breaker box panel (point where safety ground wires, white
neutral wire, utility neutral wire, and earth ground wire all
meet). The only wire that can make such a connection is one
that is not carrying any current - the bare ground wire. Even
though the white neutral wire also meets at that point, the
white wire has significant differences at both ends - because
white wire is carrying up to 20 amps current.

Others have provided examples of why the white wire and bare
safety ground wire are completely different wires at the wall
receptacle. Bottom line - the white wire and bare safety
ground wire are only same where both meet at the breaker box
safety ground.

You may even be able to see this difference with a digital
volt meter. When AC outlet powers a significant load (ie
toaster or steam iron), then a voltage difference should exist
between white neutral wire and bare copper safety ground wire
at that wall receptacle.

Are white neutral and bare copper safety wires properly
isolated? Breaker box GFCIs tend to trip (cut off power) when
bare copper white is shorted (connected) to white neutral wire
anywhere but inside the breaker box. Just another in a long
list of examples that demonstrate why white neutral and bare
copper safety ground wire are electrically different. Why one
wire cannot perform both functions.



Doesn't a similar situation exist under the hood of your car?

Two wires emerge from the alternator, a thick one and a thin one, and both
go to the positive pole of the battery.
I wonder how many people have stood pondered why that might be?

Graham.

%Profound_observation%
 
W

w_tom

Jan 1, 1970
0
No.
"... on a 3 wire outlet, from the green case ground post to the
silver white neutral post" * DOES NOT HAVE *
" ... the same potential as the bare copper safety wire has from
the green case ground post to the neutral binding posts in the
breaker box panel."
As posted earlier, the white wire and bare copper wire are
(essentially) same potential where they meet at breaker box -
the single point safety ground. Both wires have different
potential at their other (receptacle) end. That voltage
difference can even be measured with a digital volt meter when
the outlet is supporting a heavy load.

How 'different' at the far end? That answer first required
numbers - electrical parameters. Difference may be so slight
as to be unmeasureable or difference so great as to be a human
safety threat. But two wires with a common connection at one
end are not same (electrically speaking) as the other end.

Again, wire (even a superconductor wire) is an electronic
component - not a perfect conductor. Electricity at one end
of a wire is not same as at other end. To calculate the
difference, one must first apply numbers. But this difference
between two ends of any wire is why white wire cannot perform
the function of both white neutral and bare copper safety
ground. White wire and bare copper wire are wired so that
each conducts different electricity from different parts of
the same appliance. Both wires must remain separated so that
both wires conduct their electrically unique currents to the
same single point safety ground.

Do the experiment as posted previously. Connect a heavy
load to wall receptacle. Measure the AC voltage difference
between outlet safety ground and outlet neutral wire. Each
wire at the receptacle end have different potentials. 3.5
digit multimeters being so inexpensive and so ubiquitous that
anyone with a basic tool box has that meter - and can perform
this experiment.

If an outlet is drawing 20 amps, then everything in the
circuit is conducting 20 amps. BUT, the voltage (the
potential) between two wires is different at different
locations on the wire. Move one foot down a wire and the
voltage changes. Again, electricity even on one end of a one
foot wire is different at the other end. Difference may or
may not be measurable. But the difference always exists ...
because wire is another electronic component just like
resistors, capacitors, and inductors.
 
W

w_tom

Jan 1, 1970
0
Use the word 'kelvin' to further investigate this basic
electrical principle.
 
G

Graham

Jan 1, 1970
0
Use the word 'kelvin' to further investigate this basic
electrical principle.

I thought he invented the temperature scale based on Absolute Zero.

Galvani (galvinism) perhaps???
Perhaps not.

--
Graham.



%Profound_observation%
 
N

NSM

Jan 1, 1970
0
| AFAICS, the OP is not stupid, only ignorant of this particular
| subject. IMO the question was a fair one that deserved an explanation
| a little less condescending than "don't do it because it's not safe".
| In fact, I'm betting that the majority of electricians don't
| understand why they do things a certain way, they just blindly follow
| rules.

Fortunately that works well. At one time during training they did understand
the reasons, and most do now, but as long as they follow the rules all will
work out well. In really unusual cases, the local inspector is the best
resource to ask for any needed variation, or an electrical engineer can be
hired.

I do understand the reasons to this day, but it's a long winded step by step
explanation and the previously given PDF goes into it in detail.

That rule is just one of many, MANY rules. Each has it's purpose and, while
I consider myself to be as smart as any electrician, I have no problem doing
the work to code.

BTW, I recall a case in which a bunch of farmers, a VERY long way away from
an electrical service, got permission to run electricity to their farms
using a single strand of fencing wire (carrying 11 KV) on the top of a
series of poles, and using the earth itself as the return wire. Believe me
there were some very careful considerations made before allowing this, but
it did work out OK in the end.

N
 
N

NSM

Jan 1, 1970
0
|
|
| > Use the word 'kelvin' to further investigate this basic
| > electrical principle.
|
| I thought he invented the temperature scale based on Absolute Zero.

Search for (four-terminal kelvin connection) or (kelvin terminals) or
(kelvin clips) for better hits.

N
 
C

CJT

Jan 1, 1970
0
Rodney said:
Ok, For those who worry, I am NOT wiring a house like this. This is only
theoretical.
So from what you say I see that the short jumper,

There is (should be) no such jumper. Case closed.

If you see such a jumper, get your wiring reviewed by a competent
electrician before somebody gets electrocuted.

on a 3 wire outlet,
from the green case ground post to the silver white neutral post has the
same potential as the bare copper safety wire has from the green case ground
post to the neutral binding posts in the breaker box panel.. Barring all
possible disasters Is there any electrical difference that the outlet sees
where you plug things in?
If the outlet is drawing 20 amps then isn't it felt at the breaker box paned
neutral connection where the equipment ground is connected?
As a matter of fact isn't the bare copper safety wire seeing the entire
house current at that neurtal connection in the breaker box panel at the
outlet's safety ground?

I suppose that depends on what you mean by "seeing," but as you say,
it's just a theoretical question.
 
C

CJT

Jan 1, 1970
0
w_tom said:
Again, wire (even a superconductor wire) is an electronic
component - not a perfect conductor.
<snip>

You lost me there. Is "perfect" in this sentence something other than
zero resistance (e.g. it's only "perfect" to a buyer if free)?
 
C

CJT

Jan 1, 1970
0
Graham wrote:
Doesn't a similar situation exist under the hood of your car?

Two wires emerge from the alternator, a thick one and a thin one, and both
go to the positive pole of the battery.

Are you saying they're connected to the same point on the alternator,
too? I doubt it.
 
N

NSM

Jan 1, 1970
0
| Two wires emerge from the alternator, a thick one and a thin one, and both
| go to the positive pole of the battery.
| I wonder how many people have stood pondered why that might be?

Not me. One is the high current output from the stator, the other is the
input to the regulator and thence to the rotor.

N
 
R

Rodney Kelp

Jan 1, 1970
0
w_tom said:
No.
* DOES NOT HAVE *

HAS- outlet plugs have two silver screws on one side and two gold screws on
the hot side. Some of them also have push pin holes in the back; 2 on the
silver side and 2 on the gold side.
 
J

Jim Adney

Jan 1, 1970
0
If you look inside some power panels the white neutral is connected to the
same terminal block as the green ground wires.
What's the diff?

The connection between ground and neutral is made at exactly one
place, and that place is generally where the power comes into the
house, the service entrance.

After that point the ground and the neutral travel out to the rest of
the house to all the outlets that you have. The ground normally
carries no current, so there is no voltage drop between any point on
it and the actual ground at the service entrance.

The neutral carries current, so there will always be some voltage on
the neutral conductor. That voltage will depend on the distance from
the service entrance ground, the size of the conductor, and the amount
of return current being carried by the neutral. The voltage on the
neutral is usually less than 1 V, but it can be as much as 3-4 volts
in large installations with large currents.

While 3-4 volts would not be much of a safety hazard, think what would
happen if there was a problem with the neutral conductor somewhere
between your outlet and the service entrance. The voltage on the
neutral conductor would jump up to the line voltage. If you have
"grounded" your appliance to the neutral, then the external metal
parts of your appliance are now at line voltage.

For this reason, the code requires that the ground wire must not carry
any current except under fault conditions, and it also requires that
you not use the neutral to "ground" anything.

-
 
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