Power Line Grounds Near Water

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
I read an interesting article about potential drownings around docks with p
ower connections.  Some researchers say the ground connection which goes al
l the way back to the power line transformer allows power surges to reach t
he dock where it can find its way into the water.  

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

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

Anyone know much about this?  

--  

  Rick C.

  - Get 1,000 miles of free Supercharging
We've slightly trimmed the long signature. Click to see the full one.
Re: Power Line Grounds Near Water
On 10/08/2019 06:05, Rick C wrote:
Quoted text here. Click to load it
It seems a bit odd and the drawing shows ground connections at the
Quoted text here. Click to load it

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

Re: Power Line Grounds Near Water
On Saturday, 10 August 2019 08:48:55 UTC+1, Martin Brown  wrote:

Quoted text here. Click to load it

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

Re: Power Line Grounds Near Water
On Sat, 10 Aug 2019 04:21:49 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

Quoted text here. Click to load it

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.
  

Re: Power Line Grounds Near Water
On Saturday, August 10, 2019 at 3:48:55 AM UTC-4, Martin Brown wrote:
Quoted text here. Click to load it
ocked-at-virginia-lakes-researchers-say-politics-blocking-fix
Quoted text here. Click to load it
sures-not-lethal-human
Quoted text here. Click to load it

You seem to have gone off half cocked... I have a friend who is knowledgeab
le 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 n
o longer near the pan, but the trigger is locked and so not capable of firi
ng 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 wat
er.  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 wa
ter.  

Then there is this statement by the author...

"Work by Charles F. Dalziel, Richard H. Kaufmann, Edward C. Cantwell, and o
thers 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 wi
ll be lethal"

Maybe you can tell me what is wrong with it?  I think such a mistake preclu
des 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
We've slightly trimmed the long signature. Click to see the full one.
Re: Power Line Grounds Near Water
Martin Brown wrote:
Quoted text here. Click to load it

Quoted text here. Click to load it

Quoted text here. Click to load it

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/

Re: Power Line Grounds Near Water
Quoted text here. Click to load it

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.

Re: Power Line Grounds Near Water
On Sun, 11 Aug 2019 11:47:09 -0000 (UTC), Jasen Betts

Quoted text here. Click to load it

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.

Re: Power Line Grounds Near Water
On Sun, 11 Aug 2019 16:53:49 +0300, upsidedown wrote:

Quoted text here. Click to load it

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




--  
This message may be freely reproduced without limit or charge only via  
the Usenet protocol. Reproduction in whole or part through other  
We've slightly trimmed the long signature. Click to see the full one.
Re: Power Line Grounds Near Water
On Sunday, August 11, 2019 at 9:53:53 AM UTC-4, snipped-for-privacy@downunder.com wrote:
Quoted text here. Click to load it

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
We've slightly trimmed the long signature. Click to see the full one.
Re: Power Line Grounds Near Water
On 8/10/19 1:05 AM, Rick C wrote:
Quoted text here. Click to load it

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
We've slightly trimmed the long signature. Click to see the full one.
Re: Power Line Grounds Near Water
On Sat, 10 Aug 2019 04:33:36 -0400, Phil Hobbs wrote:

Quoted text here. Click to load it

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  
We've slightly trimmed the long signature. Click to see the full one.
Re: Power Line Grounds Near Water
On 10/08/2019 10:03, Cursitor Doom wrote:
Quoted text here. Click to load it

 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

Re: Power Line Grounds Near Water
On 8/10/2019 4:03 AM, Cursitor Doom wrote:
Quoted text here. Click to load it
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

Re: Power Line Grounds Near Water
On Saturday, 10 August 2019 13:59:22 UTC+1, amdx  wrote:
Quoted text here. Click to load it

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

Re: Power Line Grounds Near Water

[snip]

Quoted text here. Click to load it

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.

Re: Power Line Grounds Near Water
On Saturday, August 10, 2019 at 4:33:41 AM UTC-4, Phil Hobbs wrote:
Quoted text here. Click to load it

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
We've slightly trimmed the long signature. Click to see the full one.
Re: Power Line Grounds Near Water
On Fri, 09 Aug 2019 22:05:35 -0700, Rick C wrote:

Quoted text here. Click to load it

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!



--  
This message may be freely reproduced without limit or charge only via  
the Usenet protocol. Reproduction in whole or part through other  
We've slightly trimmed the long signature. Click to see the full one.
Re: Power Line Grounds Near Water
On Saturday, August 10, 2019 at 5:06:07 AM UTC-4, Cursitor Doom wrote:
Quoted text here. Click to load it

What is wrong with this statement???

--  

  Rick C.

  -+ Get 1,000 miles of free Supercharging
We've slightly trimmed the long signature. Click to see the full one.
Re: Power Line Grounds Near Water
On Saturday, August 10, 2019 at 10:42:37 AM UTC-4, Rick C wrote:
Quoted text here. Click to load it


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?





Site Timeline