Power Line Grounds Near Water

[Randy Day]

In article <qim19b$knr$1@dont-email.me>, curd@notformail.com says...

[snip]

sheath breaks. This doesn't affect humans, however, as our feet are
normally always too close together.

At kilovolt potentials, even pacing can be
dangerous. We do Injection Polarization
mineral surveys, at levels up to 10KV. Our
crews are instructed to stand away from the
equipment, feet together, and not to walk
about while a test is in progress.

The same applies to people walking near
downed power lines...

If you're talking about 120/240v, then yes,
the risk is much lower.

 

[Bert Hickman]

Martin Brown wrote:

On 10/08/2019 06:05, Rick C wrote:
I read an interesting article about potential drownings around docks
with power connections.  Some researchers say the ground connection
which goes all the way back to the power line transformer allows power
surges to reach the dock where it can find its way into the water.

https://www.wsls.com/news/virginia/roanoke/did-you-know-you-could-be-shocked-at-virginia-lakes-researchers-say-politics-blocking-fix




It seems a bit odd and the drawing shows ground connections at the
pole, the house and at the dock.  It's hard to imagine that even
without any defects any sort of voltage would be transferred to the
water.

Anyone know much about this?

Evidently not the people who are "researching" it. We would just about
all be dead after using 741 opamps on full voltage if they were right.

I quote from their gibberish

}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.

Around 50v rms starts to sting and might actually be dangerous if you
were in the water making a good contact with it and unable to escape. See

https://www.ecmweb.com/shock-amp-electrocution/small-contact-voltage-exposures-not-lethal-human


If you have a sensitive electrometer you can find truly terrifying
voltages between well insulated metal plates at different heights.

We're all used to working with low to moderate voltages with little more
than a minor tingle during accidental contact. So, we're naturally
skeptical when presented with evidence of low-voltage electrocution.

However, if you're immersed in water for some time, your waterlogged
skin no longer provides its normal high-resistance barrier to current
flow. Under these conditions, the effective resistance (from
outstretched hands to feet) of a human drops to the order of 300 ohms or
so. Since a current of 50 - 100 mA at 50/60 Hz can induce ventricular
fibrillation, a potential of only 15 - 30 AC volts could kill you. And,
since only 18-20 mA is sufficient to induce respiratory arrest, less
than 6 volts AC across your body could potentially cause you to drown.
Some sobering information from an open source journal:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763825/

 

[Whoey Louie]

On Saturday, August 10, 2019 at 10:50:22 AM UTC-4, Rick C wrote:

On Saturday, August 10, 2019 at 10:30:04 AM UTC-4, Whoey Louie wrote:
On Saturday, August 10, 2019 at 1:05:39 AM UTC-4, Rick C wrote:
I read an interesting article about potential drownings around docks with power connections. Some researchers say the ground connection which goes all the way back to the power line transformer allows power surges to reach the dock where it can find its way into the water.

https://www.wsls.com/news/virginia/roanoke/did-you-know-you-could-be-shocked-at-virginia-lakes-researchers-say-politics-blocking-fix

It seems a bit odd and the drawing shows ground connections at the pole, the house and at the dock. It's hard to imagine that even without any defects any sort of voltage would be transferred to the water.

Anyone know much about this?

--

Rick C.

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

Google for "stray voltage". This has been a known problem in some areas
for decades. An example is people getting shocks touching metal near
pools at their homes. Many times the power companies have investigated
and can't even figure out what is wrong, but it appears to be power taking
unexpected paths that result in some unintended things becoming energized.
The cases I've heard of though have not been fatal or even enough to give
a serious shock, more of a tingle. But I can see it potentially being
worse in water. In these cases, what they are saying is that by having
the equipment grounding conductor at the dock connected to the house
the wet area at the lake could be a better ground than the grounding electrode
system at the house. Part of the neutral current from the house will
always flow through the ground rod system, back to the utility transformer,
instead of over the neutral wire. In this case, the grounded metal of
the electric system of the dock, through you, to the water, becomes an
alternate path. The rest depends on the relative resistances of the
grounding electrode system path at the house and the resistance of the
path that you are in. That's why they are proposing that dock systems be
separately grounded at the dock, not bonded to the grounding system at the
house panel. Even if the grounding electrode system at the house is very
good, the total resistance of the path to the transformer depends on the
earth in between. If that resistance is high, then more voltage could
appear on the alternate path through the metal at the lake, through you
and into the water.

Great explanation. I've never actually understood the reason for "grounding" electrical systems. Everything done by grounding can be accomplished by using a "safety" wire which is essentially a backup neutral. As long as neutral faults can be detected such as by GFCI, why does connecting to literal "earth" make a difference?

Lightning is one big thing. Or a fault where the high voltage primary
contacts the low voltage side. With one side grounded, it limits the
fault voltage. With no earthing, you'd have 12KV going into homes,
searching for whatever path it can find to complete a circuit.

But their standard of 15 volts seems very low and while I guess it might
be capable of somehow being lethal, I've never heard of a case with voltage
that low. 24V is used for all kinds of low voltage systems, eg door bells,
HVAC control, etc. I've never heard of anyone being electrocuted from that.

Yes, because not many use such devices while up to their necks in water. I believe the voltages referred to in the article are measured across the body, not at the source.

In which case it would take even higher circuit voltage.

 

[Whoey Louie]

On Saturday, August 10, 2019 at 11:47:59 AM UTC-4, Rick C wrote:

On Saturday, August 10, 2019 at 10:59:51 AM UTC-4, Whoey Louie wrote:
On Saturday, August 10, 2019 at 10:42:37 AM UTC-4, 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???



That from everything we know, including from our own personal experience,
15 volts isn't lethal period, forget about the 8 milliseconds? I suppose
maybe you could find someone with some underlying heart problems where
if you managed to apply it just right, 15V could be lethal, but I've
never heard of such a thing. So, where did these guys come up with that
standard? Why is there no number for current?

Does your standard of something higher than 15 volts apply when you are up to your armpits in water? Have you read any of the other posts in this thread where this is explained?

Why of course. And the cite says that a person soaked with water, immersed
in water, still has a resistance of 300 ohms and that it takes 100ma to
cause cardiac arrest. Do the math. If you have some examples of people
dying from being exposed to 15 volts, I'd be happy to see them. And if
you can read, I said I believed it might be possible, under some special
circumstances.

 

[Whoey Louie]

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!

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. And of course
when you have faults you can be shocked and killed, especially if there
are multiple faults and you don't have GFCI which any responsible dock owner
would have today. The guy worrying about the docks, what is he going to
solve? There never has been a reqt in NEC that old homes and facilities
have to be brought up to current code. Putting in GFCI where they don't
exist would likely save far more lives than his new code. And that code,
like almost all the rest of the code, would apply going forward, not to
what's out there already.




> 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.

ROFL

Was it someone who hijacked your computer that started off this thread with
this:


"It seems a bit odd and the drawing shows ground connections at the pole, the house and at the dock. It's hard to imagine that even without any defects any sort of voltage would be transferred to the water. "


First you say that you can't imagine how someone at a dock could get
a shock without a fault, so I and other posters had to explain to you
how that's possible because of the neutral being grounded and now you're explaining it to us?

Yes, clearly this is not an event that happens if you think of conductors as perfect and grounds as perfect.

No shit Sherlock,


> This is not a problem caused by light bulbs and coffee pots.

Who ever said it was?



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

BS. It's not really about transients. I could put 100 amps worth of static
light bulbs and coffee pots on the house circuits. And because the
eqpt grounding conductor is tied to earth ground and the neutral,
a person standing on the dock with wet feet is an alternate path for
some of that current. How much, what voltage develops, depends on the
relative resistance of
the neutral to the transformer, the resistance of the house grounding
electrode system, the resistance of the path from the grounding electrodes
back to the transformer and the resistance of the person standing at the dock
and that path back to the transformer.

And the lift motor causing a shock isn't transients. It's a fault
with the lift motor, because otherwise that lift motor is no different
than the AC compressor coming on or the coffee pot being plugged in
at the house.

--

Rick C.

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

You make much money with all that spamming?

 

[Rick C]

On Saturday, August 10, 2019 at 8:54:50 PM UTC-4, Whoey Louie wrote:

On Saturday, August 10, 2019 at 10:50:22 AM UTC-4, Rick C wrote:
On Saturday, August 10, 2019 at 10:30:04 AM UTC-4, Whoey Louie wrote:
On Saturday, August 10, 2019 at 1:05:39 AM UTC-4, Rick C wrote:
I read an interesting article about potential drownings around docks with power connections. Some researchers say the ground connection which goes all the way back to the power line transformer allows power surges to reach the dock where it can find its way into the water.

https://www.wsls.com/news/virginia/roanoke/did-you-know-you-could-be-shocked-at-virginia-lakes-researchers-say-politics-blocking-fix

It seems a bit odd and the drawing shows ground connections at the pole, the house and at the dock. It's hard to imagine that even without any defects any sort of voltage would be transferred to the water.

Anyone know much about this?

--

Rick C.

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

Google for "stray voltage". This has been a known problem in some areas
for decades. An example is people getting shocks touching metal near
pools at their homes. Many times the power companies have investigated
and can't even figure out what is wrong, but it appears to be power taking
unexpected paths that result in some unintended things becoming energized.
The cases I've heard of though have not been fatal or even enough to give
a serious shock, more of a tingle. But I can see it potentially being
worse in water. In these cases, what they are saying is that by having
the equipment grounding conductor at the dock connected to the house
the wet area at the lake could be a better ground than the grounding electrode
system at the house. Part of the neutral current from the house will
always flow through the ground rod system, back to the utility transformer,
instead of over the neutral wire. In this case, the grounded metal of
the electric system of the dock, through you, to the water, becomes an
alternate path. The rest depends on the relative resistances of the
grounding electrode system path at the house and the resistance of the
path that you are in. That's why they are proposing that dock systems be
separately grounded at the dock, not bonded to the grounding system at the
house panel. Even if the grounding electrode system at the house is very
good, the total resistance of the path to the transformer depends on the
earth in between. If that resistance is high, then more voltage could
appear on the alternate path through the metal at the lake, through you
and into the water.

Great explanation. I've never actually understood the reason for "grounding" electrical systems. Everything done by grounding can be accomplished by using a "safety" wire which is essentially a backup neutral. As long as neutral faults can be detected such as by GFCI, why does connecting to literal "earth" make a difference?

Lightning is one big thing. Or a fault where the high voltage primary
contacts the low voltage side. With one side grounded, it limits the
fault voltage. With no earthing, you'd have 12KV going into homes,
searching for whatever path it can find to complete a circuit.

You are talking about a 12 kV line that has the other side grounded. If none of this were grounded, it wouldn't matter if you touch the wire. That's why a lineman or a squirrel can touch a hot wire as long as he isn't grounded. If the neutral wasn't grounded what would complete the path?

But the lightning issue makes sense.

But their standard of 15 volts seems very low and while I guess it might
be capable of somehow being lethal, I've never heard of a case with voltage
that low. 24V is used for all kinds of low voltage systems, eg door bells,
HVAC control, etc. I've never heard of anyone being electrocuted from that.

Yes, because not many use such devices while up to their necks in water.. I believe the voltages referred to in the article are measured across the body, not at the source.

In which case it would take even higher circuit voltage.

Yeah, what's your point?

--

Rick C.

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

 

[Rick C]

On Saturday, August 10, 2019 at 8:48:18 PM 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!


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.

And of course
when you have faults you can be shocked and killed, especially if there
are multiple faults and you don't have GFCI which any responsible dock owner
would have today. The guy worrying about the docks, what is he going to
solve? There never has been a reqt in NEC that old homes and facilities
have to be brought up to current code.

He isn't trying to change the NEC. I think he has given up on that. He is lobbying the Virginia state legislature who sets the code for the state of VA, not the NEC.

Putting in GFCI where they don't
exist would likely save far more lives than his new code. And that code,
like almost all the rest of the code, would apply going forward, not to
what's out there already.

Actually, if you think a GFCI will do the job, you didn't read the article. The current isn't coming from a defect connecting the live wire to ground.. The problem seems to be voltage transients in the ground wire itself. The researchers believe this is from a large current spike creating voltage on the neutral which is tied to the ground wire.

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.

ROFL

Was it someone who hijacked your computer that started off this thread with
this:


"It seems a bit odd and the drawing shows ground connections at the pole, the house and at the dock. It's hard to imagine that even without any defects any sort of voltage would be transferred to the water. "


First you say that you can't imagine how someone at a dock could get
a shock without a fault, so I and other posters had to explain to you
how that's possible because of the neutral being grounded and now you're explaining it to us?

I was trying to say I've not seen any docks with a ground connection. I don't have power on my dock. But I've never seen a ground connection on any dock I've been on. I would have seen one at some point.

Yes, clearly this is not an event that happens if you think of conductors as perfect and grounds as perfect.

No shit Sherlock,


This is not a problem caused by light bulbs and coffee pots.

Who ever said it was?



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


BS. It's not really about transients. I could put 100 amps worth of static
light bulbs and coffee pots on the house circuits. And because the
eqpt grounding conductor is tied to earth ground and the neutral,
a person standing on the dock with wet feet is an alternate path for
some of that current. How much, what voltage develops, depends on the
relative resistance of
the neutral to the transformer, the resistance of the house grounding
electrode system, the resistance of the path from the grounding electrodes
back to the transformer and the resistance of the person standing at the dock
and that path back to the transformer.

And the lift motor causing a shock isn't transients. It's a fault
with the lift motor, because otherwise that lift motor is no different
than the AC compressor coming on or the coffee pot being plugged in
at the house.

So everything the guy said is a lie?

There are none so blind who will not see.

--

Rick C.

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

 

[Rick C]

On Saturday, August 10, 2019 at 8:51:37 PM UTC-4, Whoey Louie wrote:

On Saturday, August 10, 2019 at 11:47:59 AM UTC-4, Rick C wrote:

Does your standard of something higher than 15 volts apply when you are up to your armpits in water? Have you read any of the other posts in this thread where this is explained?

Why of course. And the cite says that a person soaked with water, immersed
in water, still has a resistance of 300 ohms and that it takes 100ma to
cause cardiac arrest. Do the math. If you have some examples of people
dying from being exposed to 15 volts, I'd be happy to see them. And if
you can read, I said I believed it might be possible, under some special
circumstances.

So you acknowledge that 15 can be a problem??? I'm confused...

Your 100 mA is for a fatal electric shock stopping the heart. A lower current causes a severe shock that can cause a person to drown, not by stopping the heart. I think the article says that.

Maybe you should try reading it???

--

Rick C.

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

 

[Cursitor Doom]

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. :/



--
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protocols constitutes acceptance of this condition.

 

[Cursitor Doom]

On Sat, 10 Aug 2019 17:44:43 +0200, Jeroen Belleman wrote:

Safety grounding seeks to put every conductor within reach at the same
potential, so that anyone touching two things at once won't be subjected
to a potential difference. In most cases, the earth is within reach, so
that it too must be connected to the safety ground. Obviously, vehicles
do not need to have their safety ground connected to earth, except maybe
when stationary and connected to other systems.

There is also the critical issue that (in the UK at least) mains live/
line/hot wires are earth-referenced so you can get electrocuted just be
touching one hot wire. That's why those of us that work on higher voltage
equipment use isolation transformers to 'strip-off' the earth reference.




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protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

 

[Jasen Betts]

On 2019-08-10, Martin Brown <'''newspam'''@nezumi.demon.co.uk> wrote:

On 10/08/2019 06:05, Rick C wrote:
I read an interesting article about potential drownings around docks
with power connections. Some researchers say the ground connection
which goes all the way back to the power line transformer allows
power surges to reach the dock where it can find its way into the
water.

https://www.wsls.com/news/virginia/roanoke/did-you-know-you-could-be-shocked-at-virginia-lakes-researchers-say-politics-blocking-fix

It seems a bit odd and the drawing shows ground connections at the
pole, the house and at the dock. It's hard to imagine that even
without any defects any sort of voltage would be transferred to the
water.

Anyone know much about this?

Evidently not the people who are "researching" it. We would just about
all be dead after using 741 opamps on full voltage if they were right.

I quote from their gibberish

}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.

Around 50v rms starts to sting and might actually be dangerous if you
were in the water making a good contact with it and unable to escape. See

Try again with wet hands, if you get them propperly wet with impure water (maybe
add a little table salt) 5V should be enough to suprise you.

I read of someone dying while working on a 36V wind generator during a
rainstorm, but it's possible that they triggered a load dump.

--
When I tried casting out nines I made a hash of it.

 

[Jasen Betts]

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.

--
When I tried casting out nines I made a hash of it.

 

[Cursitor Doom]

On Sun, 11 Aug 2019 16:53:49 +0300, upsidedown wrote:

As long as you are fully submerged and the water has at least some
conductivity (not distilled water), all your body parts are nearly at
the same potential. So even if your skin resistance drops to 300 ohms,
not much current can flow.

By this point the conductivity of the electrolyte becomes a factor that
needs to be considered as well I would guess.




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This message may be freely reproduced without limit or charge only via
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protocols, whether for profit or not, is conditional upon a charge of
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protocols constitutes acceptance of this condition.

 

On Sun, 11 Aug 2019 11:47:09 -0000 (UTC), Jasen Betts
<jasen@xnet.co.nz> wrote:

On 2019-08-10, Martin Brown <'''newspam'''@nezumi.demon.co.uk> wrote:
On 10/08/2019 06:05, Rick C wrote:
I read an interesting article about potential drownings around docks
with power connections. Some researchers say the ground connection
which goes all the way back to the power line transformer allows
power surges to reach the dock where it can find its way into the
water.

https://www.wsls.com/news/virginia/roanoke/did-you-know-you-could-be-shocked-at-virginia-lakes-researchers-say-politics-blocking-fix

It seems a bit odd and the drawing shows ground connections at the
pole, the house and at the dock. It's hard to imagine that even
without any defects any sort of voltage would be transferred to the
water.

Anyone know much about this?

Evidently not the people who are "researching" it. We would just about
all be dead after using 741 opamps on full voltage if they were right.

I quote from their gibberish

}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.

Around 50v rms starts to sting and might actually be dangerous if you
were in the water making a good contact with it and unable to escape. See

Try again with wet hands, if you get them propperly wet with impure water (maybe
add a little table salt) 5V should be enough to suprise you.

I read of someone dying while working on a 36V wind generator during a
rainstorm, but it's possible that they triggered a load dump.

As long as you are fully submerged and the water has at least some
conductivity (not distilled water), all your body parts are nearly at
the same potential. So even if your skin resistance drops to 300 ohms,
not much current can flow.

Of course, if you touch e.g. a ladder that is not in the water and the
ladder has an elevated potential above water potential, there is a
risk.

 

[Whoey Louie]

On Saturday, August 10, 2019 at 10:28:53 PM UTC-4, Rick C wrote:

On Saturday, August 10, 2019 at 8:54:50 PM UTC-4, Whoey Louie wrote:
On Saturday, August 10, 2019 at 10:50:22 AM UTC-4, Rick C wrote:
On Saturday, August 10, 2019 at 10:30:04 AM UTC-4, Whoey Louie wrote:
On Saturday, August 10, 2019 at 1:05:39 AM UTC-4, Rick C wrote:
I read an interesting article about potential drownings around docks with power connections. Some researchers say the ground connection which goes all the way back to the power line transformer allows power surges to reach the dock where it can find its way into the water.

https://www.wsls.com/news/virginia/roanoke/did-you-know-you-could-be-shocked-at-virginia-lakes-researchers-say-politics-blocking-fix

It seems a bit odd and the drawing shows ground connections at the pole, the house and at the dock. It's hard to imagine that even without any defects any sort of voltage would be transferred to the water.

Anyone know much about this?

--

Rick C.

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Google for "stray voltage". This has been a known problem in some areas
for decades. An example is people getting shocks touching metal near
pools at their homes. Many times the power companies have investigated
and can't even figure out what is wrong, but it appears to be power taking
unexpected paths that result in some unintended things becoming energized.
The cases I've heard of though have not been fatal or even enough to give
a serious shock, more of a tingle. But I can see it potentially being
worse in water. In these cases, what they are saying is that by having
the equipment grounding conductor at the dock connected to the house
the wet area at the lake could be a better ground than the grounding electrode
system at the house. Part of the neutral current from the house will
always flow through the ground rod system, back to the utility transformer,
instead of over the neutral wire. In this case, the grounded metal of
the electric system of the dock, through you, to the water, becomes an
alternate path. The rest depends on the relative resistances of the
grounding electrode system path at the house and the resistance of the
path that you are in. That's why they are proposing that dock systems be
separately grounded at the dock, not bonded to the grounding system at the
house panel. Even if the grounding electrode system at the house is very
good, the total resistance of the path to the transformer depends on the
earth in between. If that resistance is high, then more voltage could
appear on the alternate path through the metal at the lake, through you
and into the water.

Great explanation. I've never actually understood the reason for "grounding" electrical systems. Everything done by grounding can be accomplished by using a "safety" wire which is essentially a backup neutral. As long as neutral faults can be detected such as by GFCI, why does connecting to literal "earth" make a difference?

Lightning is one big thing. Or a fault where the high voltage primary
contacts the low voltage side. With one side grounded, it limits the
fault voltage. With no earthing, you'd have 12KV going into homes,
searching for whatever path it can find to complete a circuit.

You are talking about a 12 kV line that has the other side grounded. If none of this were grounded, it wouldn't matter if you touch the wire. That's why a lineman or a squirrel can touch a hot wire as long as he isn't grounded. If the neutral wasn't grounded what would complete the path?

What would complete the path is something, unpredictable, on the other side,
or in the case of 3 phase, sides. With the primary shorted to the service
going to a house, you'd have 12KV on one hot trying to find a path and
it would be unpredictable. Starting with that 12KV far exceeds the
insulation rating of the wire, eqpt, appliances, etc. So, who knows what
and where the path would be. That's one reason grounding is preferred.
With the path being one side of the service and/or the grounded metal and
earth, the situation becomes far more predictable. That 12KV short to the
service at the utility pole would quickly find a path, arc over, before most
of it ever got to the house. Grounded systems make it easy
to find faults, trigger on them to cut off power, etc. too. Isolated
systems if used in general areas, like to power homes, are very unpredictable
when it comes to faults, which is why they are confined to special
situations, eg specific industrial needs, where those possible faults
can be determined and appropriate protection used.

But the lightning issue makes sense.


But their standard of 15 volts seems very low and while I guess it might
be capable of somehow being lethal, I've never heard of a case with voltage
that low. 24V is used for all kinds of low voltage systems, eg door bells,
HVAC control, etc. I've never heard of anyone being electrocuted from that.

Yes, because not many use such devices while up to their necks in water. I believe the voltages referred to in the article are measured across the body, not at the source.

In which case it would take even higher circuit voltage.

Yeah, what's your point?

That if that's the case, then it takes even higher stray voltage to
be lethal.

 

[Whoey Louie]

On Saturday, August 10, 2019 at 10:19:07 PM UTC-4, Rick C wrote:

On Saturday, August 10, 2019 at 8:48:18 PM 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!


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.

I read that to mean that it was while it was being lowered and the lift
was powered. But I agree that they likely meant just the metal of the
lift creating the problem, so in that case, it's just a ground loop
issue, not a fault with the lift circuit.

And of course
when you have faults you can be shocked and killed, especially if there
are multiple faults and you don't have GFCI which any responsible dock owner
would have today. The guy worrying about the docks, what is he going to
solve? There never has been a reqt in NEC that old homes and facilities
have to be brought up to current code.

He isn't trying to change the NEC. I think he has given up on that. He is lobbying the Virginia state legislature who sets the code for the state of VA, not the NEC.

Doesn't matter, same thing still applies, unless VA is doing something very
unusual. I've yet to hear of a state where when new code is adopted they
typically make it apply retroactively to what is out there. For 99% or more,
they don't. You can still hook up a three wire circuit to a dryer, using
the neutral as the eqpt ground, for example, all across the US, AFAIK.
That changed in the code for new installations decades ago.

Putting in GFCI where they don't
exist would likely save far more lives than his new code. And that code,
like almost all the rest of the code, would apply going forward, not to
what's out there already.

Actually, if you think a GFCI will do the job, you didn't read the article.

I didn't say a GFCI would "do the job". I specifically addressed the lift
issue and said that if the water is becoming energized when the lift motor
is activated, then a GFCI would trip and that any responsible owner of a
dock today would have circuits there protected by GFCI.



The current isn't coming from a defect connecting the live wire to ground. The problem seems to be voltage transients in the ground wire itself.
The researchers believe this is from a large current spike creating voltage on the neutral which is tied to the ground wire.
>

It's interesting that these researchers didn't research all that much, from
what is presented here. Notably absent is any measurement of the grounding
electrode system resistance at the house, or even if there is a code compliant
grounding electrode system at the house that is properly bonded to the
neutral. Or any attempt to identify the
source of these transients, ie is it eqpt in the house pr something else.
They appear to want to just look at the dock. For all we know, there could
be various problems back at the panel and service. But the main point here
is that whatever brief imbalance a transient can create, you'd expect that
worse could be created by static loads that are on one hot leg. Put 100 amps
worth of tea pots and heaters on one leg and I'd bet that creates a higher
voltage that's constant at the dock.

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.

ROFL

Was it someone who hijacked your computer that started off this thread with
this:


"It seems a bit odd and the drawing shows ground connections at the pole, the house and at the dock. It's hard to imagine that even without any defects any sort of voltage would be transferred to the water. "


First you say that you can't imagine how someone at a dock could get
a shock without a fault, so I and other posters had to explain to you
how that's possible because of the neutral being grounded and now you're explaining it to us?

I was trying to say I've not seen any docks with a ground connection.

Say what? All circuits at docks, pools, etc have had to have a ground
connection and all metal bonded to it for the better part of the last
century.



> I don't have power on my dock. But I've never seen a ground connection on any dock I've been on. I would have seen one at some point.

You've never seen a three prong receptacle? Or are you talking about a
ground rod at the dock bonded to the electrical system? If it's the latter,
you should know why you haven't seen it, per the article it's not only
not required, it would be a code violation.

Yes, clearly this is not an event that happens if you think of conductors as perfect and grounds as perfect.

No shit Sherlock,


This is not a problem caused by light bulbs and coffee pots.

Who ever said it was?



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


BS. It's not really about transients. I could put 100 amps worth of static
light bulbs and coffee pots on the house circuits. And because the
eqpt grounding conductor is tied to earth ground and the neutral,
a person standing on the dock with wet feet is an alternate path for
some of that current. How much, what voltage develops, depends on the
relative resistance of
the neutral to the transformer, the resistance of the house grounding
electrode system, the resistance of the path from the grounding electrodes
back to the transformer and the resistance of the person standing at the dock
and that path back to the transformer.

And the lift motor causing a shock isn't transients. It's a fault
with the lift motor, because otherwise that lift motor is no different
than the AC compressor coming on or the coffee pot being plugged in
at the house.

So everything the guy said is a lie?

Wow, where do you come up with these things.

 

[Whoey Louie]

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.

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.










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

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.

 

[Rick C]

On Sunday, August 11, 2019 at 9:53:53 AM UTC-4, upsid...@downunder.com wrote:

On Sun, 11 Aug 2019 11:47:09 -0000 (UTC), Jasen Betts
jasen@xnet.co.nz> wrote:

On 2019-08-10, Martin Brown <'''newspam'''@nezumi.demon.co.uk> wrote:
On 10/08/2019 06:05, Rick C wrote:
I read an interesting article about potential drownings around docks
with power connections. Some researchers say the ground connection
which goes all the way back to the power line transformer allows
power surges to reach the dock where it can find its way into the
water.

https://www.wsls.com/news/virginia/roanoke/did-you-know-you-could-be-shocked-at-virginia-lakes-researchers-say-politics-blocking-fix

It seems a bit odd and the drawing shows ground connections at the
pole, the house and at the dock. It's hard to imagine that even
without any defects any sort of voltage would be transferred to the
water.

Anyone know much about this?

Evidently not the people who are "researching" it. We would just about
all be dead after using 741 opamps on full voltage if they were right.

I quote from their gibberish

}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.

Around 50v rms starts to sting and might actually be dangerous if you
were in the water making a good contact with it and unable to escape. See

Try again with wet hands, if you get them propperly wet with impure water (maybe
add a little table salt) 5V should be enough to suprise you.

I read of someone dying while working on a 36V wind generator during a
rainstorm, but it's possible that they triggered a load dump.

As long as you are fully submerged and the water has at least some
conductivity (not distilled water), all your body parts are nearly at
the same potential. So even if your skin resistance drops to 300 ohms,
not much current can flow.

Of course, if you touch e.g. a ladder that is not in the water and the
ladder has an elevated potential above water potential, there is a
risk.

That was the reasoning I used to say dropping a radio into the bath water would be safe. But that is not true. The conductivity of water is enough to cause problems, but not enough to essentially be a short circuit around your body.

--

Rick C.

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

 

[Rick C]

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.

--

Rick C.

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

 

[Rick C]

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.

--

Rick C.

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