Power Line Grounds Near Water

[Rick C]

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
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[Martin Brown]

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.

--
Regards,
Martin Brown

 

[Phil Hobbs]

On 8/10/19 1:05 AM, 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?

No, but it seems intuitively clear that a lake could be a better ground
than a copper rod pounded into the soil.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[N_Cook]

On 10/08/2019 10:03, Cursitor Doom wrote:

On Sat, 10 Aug 2019 04:33:36 -0400, Phil Hobbs wrote:

No, but it seems intuitively clear that a lake could be a better ground
than a copper rod pounded into the soil.

Indeed. The only similar instance I can think of is when cattle and
racehorses can get electrocuted from the earth by a potential difference
arising between their front and back legs when a nearby underground cable
sheath breaks. This doesn't affect humans, however, as our feet are
normally always too close together.

From a utility company engineer, relating to local house flooding
issues at a meeting of residents. Apparently fresh-water flooding is
worse than sea-water flooding, as
a/ sea-water is more likely to trip protection devices and quicker
b/ the area of electrified water is much greater for fresh water


--
Monthly public talks on science topics, Hampshire , England
<http://diverse.4mg.com/scicaf.htm>

 

[Cursitor Doom]

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!



--
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protocols constitutes acceptance of this condition.

 

[Cursitor Doom]

On Sat, 10 Aug 2019 04:33:36 -0400, Phil Hobbs wrote:

No, but it seems intuitively clear that a lake could be a better ground
than a copper rod pounded into the soil.

Indeed. The only similar instance I can think of is when cattle and
racehorses can get electrocuted from the earth by a potential difference
arising between their front and back legs when a nearby underground cable
sheath breaks. This doesn't affect humans, however, as our feet are
normally always too close together.




--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
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.

 

On Saturday, 10 August 2019 08:48:55 UTC+1, Martin Brown wrote:

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.

Much lower voltages than that can be unpleasant if you are partly
immersed in water. I once had a very painful shock from two series-
connected 9V batteries in a hydrophone amplifier when I was standing
waist deep in sea water. (I was fitting new batteries to the amplifier
which was in a waterproof housing floating above a coral reef. The
battery negative was grounded to the seawater through defects in the
outer sheath of the shielded cable which was a few hundred metres
long and I touched the positive terminal which would have been at
about +20Vdc.)

John

 

On Sat, 10 Aug 2019 04:21:49 -0700 (PDT), jrwalliker@gmail.com wrote:

On Saturday, 10 August 2019 08:48:55 UTC+1, Martin Brown wrote:

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.

Much lower voltages than that can be unpleasant if you are partly
immersed in water. I once had a very painful shock from two series-
connected 9V batteries in a hydrophone amplifier when I was standing
waist deep in sea water. (I was fitting new batteries to the amplifier
which was in a waterproof housing floating above a coral reef. The
battery negative was grounded to the seawater through defects in the
outer sheath of the shielded cable which was a few hundred metres
long and I touched the positive terminal which would have been at
about +20Vdc.)

In the old days the standard method to determine why a flashlight did
not work, was the bulb dead or the battery empty. Just touch both
electrodes of the 4.5 V flashlight battery with your tongue. If you
get an unpleasant jolt, the battery was OK, hence the bulb was faulty.

 

[amdx]

On 8/10/2019 4:03 AM, Cursitor Doom wrote:

On Sat, 10 Aug 2019 04:33:36 -0400, Phil Hobbs wrote:

No, but it seems intuitively clear that a lake could be a better ground
than a copper rod pounded into the soil.

Indeed. The only similar instance I can think of is when cattle and
racehorses can get electrocuted from the earth by a potential difference
arising between their front and back legs when a nearby underground cable
sheath breaks. This doesn't affect humans, however, as our feet are
normally always too close together.



I have a friend that does some underwater welding, on occasion

it has been a shocking experience.
I wish I could remember the reasons that caused this to happen,
but I don't, next time I see him I'll ask.
Mikek

 

[Rick C]

On Saturday, August 10, 2019 at 4:33:41 AM UTC-4, Phil Hobbs wrote:

On 8/10/19 1:05 AM, 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?


No, but it seems intuitively clear that a lake could be a better ground
than a copper rod pounded into the soil.

Not sure what your point is exactly. What are you trying to say but not actually saying?

--

Rick C.

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

 

[Rick C]

On Saturday, August 10, 2019 at 3:48:55 AM UTC-4, 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.

You seem to have gone off half cocked... I have a friend who is knowledgeable and told me about early firearms. I now know where this expression came from. Half cocked is a safety position in flintlocks where the flint is no longer near the pan, but the trigger is locked and so not capable of firing until the hammer is fully cocked. So going off half cocked means firing for no good reason and potentially causing damage or harm... go figure.

All the data you posted above do not apply when a person is immersed in water. Note the title of the article you reference... "Small Contact Voltage Exposures". Small contact is used to specifically exclude situations where the current can enter the skin over larger areas such as when wet or in water.

Then there is this statement by the author...

"Work by Charles F. Dalziel, Richard H. Kaufmann, Edward C. Cantwell, and others have shown that it is the volt-amps (VA) energy, or power measured in watt-seconds (W-sec), that ultimately determines if an electrical shock will be lethal"

Maybe you can tell me what is wrong with it? I think such a mistake precludes believing much the author has to say. Heck, the author doubles down by making the same mistake elsewhere showing it is not a simple typo.

--

Rick C.

+ Get 1,000 miles of free Supercharging
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[Whoey Louie]

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.

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..

 

On Saturday, 10 August 2019 13:59:22 UTC+1, amdx wrote:

On 8/10/2019 4:03 AM, Cursitor Doom wrote:
On Sat, 10 Aug 2019 04:33:36 -0400, Phil Hobbs wrote:

No, but it seems intuitively clear that a lake could be a better ground
than a copper rod pounded into the soil.

Indeed. The only similar instance I can think of is when cattle and
racehorses can get electrocuted from the earth by a potential difference
arising between their front and back legs when a nearby underground cable
sheath breaks. This doesn't affect humans, however, as our feet are
normally always too close together.



I have a friend that does some underwater welding, on occasion
it has been a shocking experience.
I wish I could remember the reasons that caused this to happen,
but I don't, next time I see him I'll ask.
Mikek

An Icelandic welder died (of electrocution) when a wave washed
over him while he was repairing his ship's hull during one of
the "Cod Wars".

John

 

[Rick C]

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???

--

Rick C.

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

 

[Whoey Louie]

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?

 

[Whoey Louie]

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.

 

[Rick C]

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?

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.

--

Rick C.

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

 

[Jeroen Belleman]

On 2019-08-10 16:50, Rick C wrote:

On Saturday, August 10, 2019 at 10:30:04 AM UTC-4, Whoey Louie
wrote:
[Poorly informed blather]

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?

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.

The current flowing through electrical appliances should flow
from hot to neutral, never to earth. If the earth conductor
has a current, that's a fault! The neutral conductor is called
that way because at some point, it's connected to ground too,
however, since it has a finite resistance and conducts a current,
its potential is not necessarily the same as the safety ground.

Jeroen Belleman

 

[Rick C]

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?

--

Rick C.

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

 

[Rick C]

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

--

Rick C.

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