Power Line Grounds Near Water

[Cursitor Doom]

On Sun, 11 Aug 2019 09:34:57 -0700, Rick C wrote:

Huh? A GFCI is designed to detect unbalance of current in the neutral
and hot wires.

IMBALANCE! I think at least half your problem is not so much with the
science, but with phraseology and plain English comprehension.



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[Cursitor Doom]

On Sun, 11 Aug 2019 09:31:16 -0700, Rick C wrote:

On Sunday, August 11, 2019 at 5:26:07 AM UTC-4, Cursitor Doom wrote:
On Sat, 10 Aug 2019 07:42:33 -0700, Rick C wrote:

On Saturday, August 10, 2019 at 5:06:07 AM UTC-4, Cursitor Doom
wrote:
On Fri, 09 Aug 2019 22:05:35 -0700, Rick C wrote:

Anyone know much about this?

Yeah, someone doesn't know what they're talking about:

"Erler said an electrical current is considered lethal if it's above
15 Volts rms for 8.3 milliseconds. In the case he presented Thursday
night,
he measured a blip of current at 18.7 Volts rms for 40 milliseconds,
far over the lethal amount. "

Not exactly confidence inspiring!

What is wrong with this statement???

Are you kidding? The author, like 99% of the population, clearly
doesn't know the difference between current and voltage. I'd assumed
everyone here would at least know that, but I never cease to be amazed.
:/

They already established the threshold for their conditions (person in
water) was about 15 volts. You, of all people, should know E = I*R. So
if the R is constant, current is proportional to voltage.

Why do people get so wigged out when someone talks about dangerous
voltages. I bet there's an XKCD cartoon about this.

I think you're missing my point here. I'm assuming the issue here is with
the copywriter rather than the scientists. I have to assume the
scientists know the difference between current and volts!

Here's the quote: "Erler said an electrical current is considered lethal
if it's above 15 Volts rms for 8.3 milliseconds."

You do realise 15V rms is not a measure of current, right?



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[Rick C]

On Sunday, August 11, 2019 at 1:11:46 PM UTC-4, Whoey Louie wrote:

On Sunday, August 11, 2019 at 12:35:01 PM UTC-4, Rick C wrote:

Huh? A GFCI is designed to detect unbalance of current in the neutral and hot wires. I don't follow what you are saying about cutting the ground wire. Where do you cut it? I believe this no longer adheres to code no matter what... unless you are talking about providing a separate ground rod for the dock.

What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

The sources of the transients are not actually known. It may be that there are issues with grounding at the source and there are transients on both the hot and neutral lines. A GFCI won't prevent common mode currents from flowing in both sides of the power line.

Of course we haven't heard the other side of the story, ie why the NEC
folks don't appear to buy into it, what their concerns are. In issues
like this, there frequently isn't an ideal solution, you're frequently
having to trade off one potential problem for another, but reducing the
chances of getting a shock, you would think would override most other
concerns.

From the article the NEC guys just don't want to hear about it. I get that.. I expect they hear from any number of individuals with suggestions. If these guys get enough attention from the Virginia legislature maybe the NEC will pick up the ball and run with it. Maybe these guys are wrong about some aspects of the problem. But *something* kills people in the water around docks and these guys have measured dangerous voltages which should be investigated.

I have read reports of this before including people who died trying to save others. The news reports are not investigations and the assumption is always that there is something wrong with the wiring.

--

Rick C.

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[Rick C]

On Sunday, August 11, 2019 at 12:41:22 PM UTC-4, Cursitor Doom wrote:

On Sun, 11 Aug 2019 09:31:16 -0700, Rick C wrote:

On Sunday, August 11, 2019 at 5:26:07 AM UTC-4, Cursitor Doom wrote:
On Sat, 10 Aug 2019 07:42:33 -0700, Rick C wrote:

On Saturday, August 10, 2019 at 5:06:07 AM UTC-4, Cursitor Doom
wrote:
On Fri, 09 Aug 2019 22:05:35 -0700, Rick C wrote:

Anyone know much about this?

Yeah, someone doesn't know what they're talking about:

"Erler said an electrical current is considered lethal if it's above
15 Volts rms for 8.3 milliseconds. In the case he presented Thursday
night,
he measured a blip of current at 18.7 Volts rms for 40 milliseconds,
far over the lethal amount. "

Not exactly confidence inspiring!

What is wrong with this statement???

Are you kidding? The author, like 99% of the population, clearly
doesn't know the difference between current and voltage. I'd assumed
everyone here would at least know that, but I never cease to be amazed.
:/

They already established the threshold for their conditions (person in
water) was about 15 volts. You, of all people, should know E = I*R. So
if the R is constant, current is proportional to voltage.

Why do people get so wigged out when someone talks about dangerous
voltages. I bet there's an XKCD cartoon about this.

I think you're missing my point here. I'm assuming the issue here is with
the copywriter rather than the scientists. I have to assume the
scientists know the difference between current and volts!

Here's the quote: "Erler said an electrical current is considered lethal
if it's above 15 Volts rms for 8.3 milliseconds."

You do realise 15V rms is not a measure of current, right?

I realize the dangerous current happens when the voltage is above 15 volts.

--

Rick C.

---- Get 1,000 miles of free Supercharging
---- Tesla referral code - https://ts.la/richard11209

 

[Whoey Louie]

On Sunday, August 11, 2019 at 12:35:01 PM UTC-4, Rick C wrote:

On Sunday, August 11, 2019 at 8:31:23 AM UTC-4, Jasen Betts wrote:
On 2019-08-11, Rick C <gnuarm.deletethisbit@gmail.com> wrote:

Can you even read? I didn't say people could not be shocked at docks,
I acknowledged that they could be. What you can't understand is that the
example cited, someone getting a shock when the lift motor is energized
and not getting shocked when it's not, indicates a FAULT.

Ok, you didn't read the description of the issue very well. The article talked about "with the lift in the water", not energized. The metallic cables of the lift conducted the ground circuit to the water.


So if you cut the ground wire and fit a GFCI on the line that could fix it, but
you'd need a GFCI that's designed to fail safe.

Huh? A GFCI is designed to detect unbalance of current in the neutral and hot wires. I don't follow what you are saying about cutting the ground wire. Where do you cut it? I believe this no longer adheres to code no matter what... unless you are talking about providing a separate ground rod for the dock.

What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

Of course we haven't heard the other side of the story, ie why the NEC
folks don't appear to buy into it, what their concerns are. In issues
like this, there frequently isn't an ideal solution, you're frequently
having to trade off one potential problem for another, but reducing the
chances of getting a shock, you would think would override most other
concerns.

 

[Cursitor Doom]

On Sun, 11 Aug 2019 09:49:40 -0700, Rick C wrote:

Did you read any of the article? Do you not understand (which they
clearly indicated) that startup transients of motors and such are much
larger than the static currents of coffee pots?

WTF is a "static current"??



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[Rick C]

On Sunday, August 11, 2019 at 11:28:42 AM UTC-4, Whoey Louie wrote:

On Saturday, August 10, 2019 at 11:46:22 AM UTC-4, Rick C wrote:
On Saturday, August 10, 2019 at 10:56:16 AM UTC-4, Whoey Louie wrote:
On Saturday, August 10, 2019 at 10:30:04 AM UTC-4, Whoey Louie wrote:

Forgot to add the comment about this:

"We tested the water in one where there had been a shock and found nothing," Harrington said. "We then put the lift down in the water as it had been described when the shock happened, and the device lit right up."

I don't see how this would happen with a properly wired system. It would
seem it has to have a fault. With no fault, the current path would be
from the house hot to the dock, through the lift motor, back to the
house on the neutral. At that point it's just like any other load in
the house, so what's going on at the dock, the metal getting energized,
should not depend on that lift
motor being energized or not, unless it has a fault. And code has
required GFCI at docks for decades now, it would trip in this case and
even if it's an old installation, it's easy to add GFCI and you'd be
a fool not to.

I guess that's why people are not shocked at docks. Oh, wait, they are! If you pay attention to what they wrote they seem to be finding, not the main current flowing, but transients that cause voltages to show up on the normal routes. The earth ground will have a connection to neutral at the house. Any voltage showing up along the resistance of the neutral can show up on the protective earth wire which can lead right to the water.

Yes, clearly this is not an event that happens if you think of conductors as perfect and grounds as perfect. This is not a problem caused by light bulbs and coffee pots.

Explain to us how a static 100A neutral current at the panel from
light bulbs and coffee pots isn't going to create a voltage at the dock.
Part of it will flow through the neutral to the utility, part will flow
through the grounding electrodes at the house back to the utility and
part of it will flow through the eqpt grounding conductor to the dock
and through whatever paths it finds there to earth, including any humans.
And it's static, not just an impulse. I agree transients of lesser
currents could probably create the same voltage because we're dealing
with impedances, but static loads would be an issue too.

Did you read any of the article? Do you not understand (which they clearly indicated) that startup transients of motors and such are much larger than the static currents of coffee pots?

Missing in all this by these "researchers" is any measurement of what's
going on at the house panel. For example, what was the resistance of
the grounding electrode system? What did that consist of? Did they
do anything to try to identify the source of these transients? Cam
they be seen at the panel? It's particularly hard to imagine how a typical
transient from the power line is making it's way all the way to the
dock. From that article, they are focused only on the dock. What they
are proposing could be a good idea. But if it's a good idea there,
then why not at pools? I don't see people being shocked and electrocuted
at swimming pools and all the metal there is, or is supposed to be,
bonded to the ground system of the house. So, you'd think there would
be the same thing happening.

I don't know about pools. I don't see how there would be current through the water in a pool. The pool is electrically isolated within the pool confinement. Where would the two electrodes be? The concrete is sealed, so current doesn't go through that.


> The transients in question are short duration but high current which then challenge the assumptions we commonly make regarding our utilities.

What assumptions would those be?

From that article there is no indication they measured what the currents
of any of the transients in question were, nor any attempt to identify
the source.

Yeah, what's your point? They evaluated existing installations and also installations which were then brought up to code. They said the upgraded installations were actually worse. I'm not sure what code changes were required.

--

Rick C.

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[Whoey Louie]

On Sunday, August 11, 2019 at 1:26:54 PM UTC-4, Rick C wrote:

On Sunday, August 11, 2019 at 1:11:46 PM UTC-4, Whoey Louie wrote:
On Sunday, August 11, 2019 at 12:35:01 PM UTC-4, Rick C wrote:

Huh? A GFCI is designed to detect unbalance of current in the neutral and hot wires. I don't follow what you are saying about cutting the ground wire. Where do you cut it? I believe this no longer adheres to code no matter what... unless you are talking about providing a separate ground rod for the dock.

What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

The sources of the transients are not actually known.

I noted that and that there was no indication that any attempt was made
to find the source.



> It may be that there are issues with grounding at the source

I specifically noted that when I said there is no indication they
even examined the grounding electrode system or took any measurements
there.




>and there are transients on both the hot and neutral lines. A GFCI won't prevent common mode currents from flowing in both sides of the power line.

Nor will it prevent a large static neutral current from generating
a voltage capable of shocking at the dock.

Of course we haven't heard the other side of the story, ie why the NEC
folks don't appear to buy into it, what their concerns are. In issues
like this, there frequently isn't an ideal solution, you're frequently
having to trade off one potential problem for another, but reducing the
chances of getting a shock, you would think would override most other
concerns.

From the article the NEC guys just don't want to hear about it.

I find that hard to believe, as they are updating the code every year
and from all that I see, they are very concerned about safety,
so I would think they looked into the merits of this. What their
position is, we don't know.



> I get that. I expect they hear from any number of individuals with suggestions.

It's not the numbers, it's what the issue they have identified is,
whether it;s legitimate and if there is a solution that makes overall
safety better. It could be that despite all the measuring, there
are few or no cases of people being injured or dead due to this.
Isn't it a bit curious that in that article there are no examples,
no cites of actual numbers?




If these guys get enough attention from the Virginia legislature maybe the NEC will pick up the ball and run with it. Maybe these guys are wrong about some aspects of the problem. But *something* kills people in the water around docks and these guys have measured dangerous voltages which should be investigated.

I have read reports of this before including people who died trying to save others. The news reports are not investigations and the assumption is always that there is something wrong with the wiring.

It's almost never an assumption, these fatalities are investigated
and the cause usually determined. And in all the lethal shocks that
I've seen reported, there has been a fault.

 

[Wolf Bagger]

On 2019-08-11 10:11, Whoey Louie wrote:

What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

This is a recognised configuration in UK wiring regulations, and is
called a TT system in IEC terminology.

https://en.m.wikipedia.org/wiki/Earthing_system#TT_network

The US is still using technology considered modern in 1876 as usual.

 

[Rick C]

On Sunday, August 11, 2019 at 3:29:17 PM UTC-4, Wolf Bagger wrote:

On 2019-08-11 10:11, Whoey Louie wrote:
What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

This is a recognised configuration in UK wiring regulations, and is
called a TT system in IEC terminology.

https://en.m.wikipedia.org/wiki/Earthing_system#TT_network

The US is still using technology considered modern in 1876 as usual.

Lol! Yes, I am very familiar with TT installations. They were done to save a single conductor in the local power line. I am told they are deprecated in the UK and most modern installations have the TN-S like the US. Not sure if that is true. I'm also told many TN-S installations are converted to TT when the foil used for the earth connections corrodes and not replaced.. Then a local ground must be installed and bonded to all earth wires in the house. I'd rather see them fix the wire.

I'm glad the US uses TN-S. It is the safest of any of the conventions. I think you must be confusing this with something else.

--

Rick C.

--+- Get 1,000 miles of free Supercharging
--+- Tesla referral code - https://ts.la/richard11209

 

[Rick C]

On Sunday, August 11, 2019 at 3:29:17 PM UTC-4, Wolf Bagger wrote:

On 2019-08-11 10:11, Whoey Louie wrote:
What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

This is a recognised configuration in UK wiring regulations, and is
called a TT system in IEC terminology.

https://en.m.wikipedia.org/wiki/Earthing_system#TT_network

The US is still using technology considered modern in 1876 as usual.

Lol! Yes, I am very familiar with TT installations. They were done to save a single conductor in the local power line. I am told they are deprecated in the UK and most modern installations have the TN-S like the US. Not sure if that is true. I'm also told many TN-S installations are converted to TT when the foil used for the earth connections corrodes and not replaced.. Then a local ground must be installed and bonded to all earth wires in the house. I'd rather see them fix the wire.

I'm glad the US uses TN-S. It is the safest of any of the conventions. I think you must be confusing this with something else.

--

Rick C.

--+- Get 1,000 miles of free Supercharging
--+- Tesla referral code - https://ts.la/richard11209

 

[Whoey Louie]

On Sunday, August 11, 2019 at 4:07:39 PM UTC-4, Cursitor Doom wrote:

On Sun, 11 Aug 2019 10:17:18 -0700, Rick C wrote:

I realize the dangerous current happens when the voltage is above 15
volts.

OK, fine. But when I'm reading through an article like that and come
across such sloppy writing it really shakes my faith in the veracity of
the entire contents and I generally don't bother reading any further.
This is something that would never happen fifty or sixty years ago, which
is why I prefer text books from the 1930s and 1940s. The clarity and
precision of language back then was immeasurably better than what we find
today. And it's really no surprise when there are so many writers around
nowadays who learned English in the kind of school Bill Sloman would
approve of.




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Really? This is a local TV station article, not one published in the IEEE.
Actually for something written by a TV reporter, I'd say it's excellent,
much better than 99% of the ones I've seen over the ages.

 

[Whoey Louie]

On Sunday, August 11, 2019 at 3:29:17 PM UTC-4, Wolf Bagger wrote:

On 2019-08-11 10:11, Whoey Louie wrote:
What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

This is a recognised configuration in UK wiring regulations, and is
called a TT system in IEC terminology.

https://en.m.wikipedia.org/wiki/Earthing_system#TT_network

The US is still using technology considered modern in 1876 as usual.

From your cite:


"TT networkEdit

In a TT (terre-terre) earthing system, the protective earth connection for the consumer is provided by a local earth electrode, (sometimes referred to as the Terra-Firma connection) and there is another independently installed at the generator. There is no 'earth wire' between the two. "


That exactly describes the system in place in the article, that's showing
potentially dangerous voltage at the dock. It's what I have here, it's
exactly what just about all homes have in the US. They have a grounding
electrode system at the disconnect at the house, there is no ground wire
back to the generator. Was there ever? Hello?

 

[Cursitor Doom]

On Sun, 11 Aug 2019 10:17:18 -0700, Rick C wrote:

I realize the dangerous current happens when the voltage is above 15
volts.

OK, fine. But when I'm reading through an article like that and come
across such sloppy writing it really shakes my faith in the veracity of
the entire contents and I generally don't bother reading any further.
This is something that would never happen fifty or sixty years ago, which
is why I prefer text books from the 1930s and 1940s. The clarity and
precision of language back then was immeasurably better than what we find
today. And it's really no surprise when there are so many writers around
nowadays who learned English in the kind of school Bill Sloman would
approve of.




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[Rick C]

On Sunday, August 11, 2019 at 4:22:39 PM UTC-4, Whoey Louie wrote:

On Sunday, August 11, 2019 at 3:29:17 PM UTC-4, Wolf Bagger wrote:
On 2019-08-11 10:11, Whoey Louie wrote:
What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

This is a recognised configuration in UK wiring regulations, and is
called a TT system in IEC terminology.

https://en.m.wikipedia.org/wiki/Earthing_system#TT_network

The US is still using technology considered modern in 1876 as usual.

From your cite:


"TT networkEdit

In a TT (terre-terre) earthing system, the protective earth connection for the consumer is provided by a local earth electrode, (sometimes referred to as the Terra-Firma connection) and there is another independently installed at the generator. There is no 'earth wire' between the two. "


That exactly describes the system in place in the article, that's showing
potentially dangerous voltage at the dock. It's what I have here, it's
exactly what just about all homes have in the US. They have a grounding
electrode system at the disconnect at the house, there is no ground wire
back to the generator. Was there ever? Hello?

You should learn about things before you post. There is no galvanic connection to the generator, so it would not matter if it was grounded or not. The galvanic connection is from the transformer which IS grounded and an earth wire is provided to the house. There can be another ground at the house, but that is usually to the water or gas line coming in from underground rather than a separate ground rod connection like they use in a TT system where the ground connection must be below some resistance. One of the problems with a TT system is poor soil not providing a good enough ground connection.

Hello?

--

Rick C.

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[Cursitor Doom]

On Sun, 11 Aug 2019 13:24:52 -0700, Whoey Louie wrote:

Really? This is a local TV station article, not one published in the
IEEE.
Actually for something written by a TV reporter, I'd say it's excellent,
much better than 99% of the ones I've seen over the ages.

Oh, a TV reporter? In that case it's an amazingly accurate, beautifully-
crafted piece of journalistic excellence!




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[Whoey Louie]

On Sunday, August 11, 2019 at 4:32:26 PM UTC-4, Rick C wrote:

On Sunday, August 11, 2019 at 3:29:17 PM UTC-4, Wolf Bagger wrote:
On 2019-08-11 10:11, Whoey Louie wrote:
What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

This is a recognised configuration in UK wiring regulations, and is
called a TT system in IEC terminology.

https://en.m.wikipedia.org/wiki/Earthing_system#TT_network

The US is still using technology considered modern in 1876 as usual.

Lol! Yes, I am very familiar with TT installations. They were done to save a single conductor in the local power line.

Wrong again. Look at the diagram shown in his link of the TT installation,
It shows 3-phase Wye to a consumer, with neutral. The earth is not used
to transfer power. What you are talking about now is a single wire earth
return, even further off into the wilderness.






I am told they are deprecated in the UK and most modern installations have the TN-S like the US. Not sure if that is true. I'm also told many TN-S installations are converted to TT when the foil used for the earth connections corrodes and not replaced. Then a local ground must be installed and bonded to all earth wires in the house. I'd rather see them fix the wire.

I'm glad the US uses TN-S. It is the safest of any of the conventions. I think you must be confusing this with something else.

Now you're telling us what is safer, when you started this by not being
able to understand how there was stray voltage at the dock?
And BTW, even the title of the thread is wrong. That article you cited
is not about "power lines near docks". There is no power line near
the dock. It's about voltages from unintended ground current from the
equipment grounding conductor at a dock.

And those diagrams of the power systems are incomplete and misleading.
They show a "consumer" and then talk about power being delivered to
devices. WTF does any of that mean? Is the consumer boundary at
the house panel or the toaster? It's important because in the US
there is a huge difference. The US has no separate ground
wire between generator or transformer and your house. It's a
neutral earthed at the transformer and at the main disconnect at the
house. From there into the house, it's a separate neutral and ground.
None of those diagrams show that, none show the required earthing at
the house, which has been part of code forever. It's wrong, very wrong.

 

[Whoey Louie]

On Sunday, August 11, 2019 at 4:39:01 PM UTC-4, Rick C wrote:

On Sunday, August 11, 2019 at 4:22:39 PM UTC-4, Whoey Louie wrote:
On Sunday, August 11, 2019 at 3:29:17 PM UTC-4, Wolf Bagger wrote:
On 2019-08-11 10:11, Whoey Louie wrote:
What he's saying is to use a GFCI on the dock circuit, which has been
required in code for decades and to cut the ground
wire that runs to the house panel. The GFCI will protect if there is any fault
by detecting the current imbalance. I would also install at least one
good ground rod at the dock and bond that to the electric grounds there
instead of having it tied
to the house ground system. Of course that is not code compliant, but
it appears better to me than the alternative and if you include the new
ground rod at the dock, it's what the guys in that article are trying to
get implemented.

This is a recognised configuration in UK wiring regulations, and is
called a TT system in IEC terminology.

https://en.m.wikipedia.org/wiki/Earthing_system#TT_network

The US is still using technology considered modern in 1876 as usual.

From your cite:


"TT networkEdit

In a TT (terre-terre) earthing system, the protective earth connection for the consumer is provided by a local earth electrode, (sometimes referred to as the Terra-Firma connection) and there is another independently installed at the generator. There is no 'earth wire' between the two. "


That exactly describes the system in place in the article, that's showing
potentially dangerous voltage at the dock. It's what I have here, it's
exactly what just about all homes have in the US. They have a grounding
electrode system at the disconnect at the house, there is no ground wire
back to the generator. Was there ever? Hello?

You should learn about things before you post. There is no galvanic connection to the generator,

Maybe you should learn terms before you use them. Galvanic ISOLATION is
used to avoid corrosion with dissimilar metals, it has nothing whatever
to do with earthing of electrical systems, the term is never used.
If you're claiming that generators at the power plant are not earthed,
I'd like to see some references for that.

More to the point, you have an incredible ability to take something
relatively simple and go off into the wilderness, now you're talking
about generators, when the dock issue has absolutely nothing to do
with generators. It's a simple multi-path earth ground problem.
And that house system with dock is earthed at the main disconnect,
just like the example of that TT system, that was presented as some
European better idea. Capiche?



>so it would not matter if it was grounded or not. The galvanic connection is from the transformer which IS grounded and an earth wire is provided to the house.

Maybe you should read before you post? NEC says nothing about "galvanic"
anything at the panel or at the transformer. And it's wrong too.
The transformer is earthed at the street and the house system ground
system is earthed at the main disconnect. At both the transformer end
and at the house main disconnect end they are bonded to the neutral.



> There can be another ground at the house, but that is usually to the water or gas line coming in from underground rather than a separate ground rod connection like they use in a TT system where the ground connection must be below some resistance.

More BS. It's required by code that the service be earthed at the main
disconnect, there is no option. It's been like that practically forever.
And if a metal underground water line is
present, it *must* be part of the grounding electrode system. Other
permissible ground electrodes include ground rods, Ufers, ground rings,
ground plates, etc... One or more of those can be used as the grounding
electrode system. Of course we don't know what was used, or if it's
even connected correctly in the example from that article, because
they showed no interest in anything at the house panel, which is quite
remarkable.

One of the problems with a TT system is poor soil not providing a good enough ground connection.

Hello?

Yes, hello indeed. That's a potential problem with just about any
earthing system. What was the resistance of the grounding electrodes
at the system in the dock example? What was used? We don't know,
because apparently they didn't bother to check any of that. Maybe
that's part of why the NEC folks didn't pay much attention to them?

 

[Rick C]

On Sunday, August 11, 2019 at 9:46:22 PM UTC-4, Wolf Bagger wrote:

On 2019-08-11 13:32, Rick C wrote:
I'm glad the US uses TN-S. It is the safest of any of the conventions. I think you must be confusing this with something else.


This is what the UK almost universally uses for the primary supply as
well (where it was traditionally known as PME - "protective multiple
earthing"), with the exception of rural locations which might be
supplied by a pole transformer instead of a substation with substantial
earthing provision.

I'm pretty sure PME uses a single conductor for earth and neutral from the transformer to the premises. TN-S uses a separate conductors for earth and neutral.

--

Rick C.

-+-- Get 1,000 miles of free Supercharging
-+-- Tesla referral code - https://ts.la/richard11209

 

[Wolf Bagger]

On 2019-08-11 13:32, Rick C wrote:>

I'm glad the US uses TN-S. It is the safest of any of the conventions. I think you must be confusing this with something else.

This is what the UK almost universally uses for the primary supply as
well (where it was traditionally known as PME - "protective multiple
earthing"), with the exception of rural locations which might be
supplied by a pole transformer instead of a substation with substantial
earthing provision.

TT is still indicated for external locations removed from the primary
location where a supply is terminated such as sheds, garages,
poolhouses, docks, etc. to deal with problems caused by conductor
resistance.