Power Line Grounds Near Water

[Martin Brown]

On 11/08/2019 21:32, 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. 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.

The strange thing is that despite using half the voltage in the US as
compared to the UK you electrocute a heck of a lot more people in the
home every year. By about two orders of magnitude today if the ONS
statistics and US electrocutions stats are to be believed.

https://www.rightdiagnosis.com/e/electrocution/stats.htm

https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=61494

UK is also mostly TN-S now although many homes also have a local earth
bond into the soil at the premises - a hangover from the original TT.
Our soil is really rather wet most of the time so it works quite well.

And at least some of those UK electrocutions are Darwin award candidates
balancing electric fires on the corner of their baths in winter.

--
Regards,
Martin Brown

 

[Rick C]

On Monday, August 12, 2019 at 3:43:40 PM UTC-4, Martin Brown wrote:

On 11/08/2019 21:32, 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. 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.

The strange thing is that despite using half the voltage in the US as
compared to the UK you electrocute a heck of a lot more people in the
home every year. By about two orders of magnitude today if the ONS
statistics and US electrocutions stats are to be believed.

https://www.rightdiagnosis.com/e/electrocution/stats.htm

https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=61494

UK is also mostly TN-S now although many homes also have a local earth
bond into the soil at the premises - a hangover from the original TT.
Our soil is really rather wet most of the time so it works quite well.

And at least some of those UK electrocutions are Darwin award candidates
balancing electric fires on the corner of their baths in winter.

The hams I talk to seem to feel dry, sandy soils are not at all uncommon. They are the ones telling me it is not uncommon to have difficulty achieving an earth that is conductive enough to meet the requirements.

I expect the statistic you are citing is not evaluated the same as in the US. I can't find a source for that number. One number I found says "around 30". I also noticed the number in the forum you found are for deaths "caused by electric shocks in the home". I believe the number for the US is all locations. I'm also not sure what number you are using.

I found from the National Center for Health Statistics (NCHS) 257 deaths from electrocution occurred in the US during 2013, the lowest of the steadily declining numbers over the 10 year period.

The only number I can find for the UK is 30 from the "Health and Safety Executive" for an unstated year. I did find another forum with numbers up to 2005 for "fatalities from accidental exposure to electric current in England & Wales" which is 25 in 2003. The number for "fatalities in the home" for all of Great Britan in 2006 rises to 13.

Until you find better sources of data, I don't see how you can compare US and UK.

--

Rick C.

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

 

[Rick C]

On Monday, August 12, 2019 at 8:01:43 PM UTC-4, George Herold 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

I'm late to reading any of this... seems to me the problem
is mostly associated with metal boat launches.... so maybe
some guide lines/ rules there.

(knowing almost nothing of power engineering),
Couldn't we make boat launches that floated the
ground some* DC to 60 Hz... and a few harmonics.?

George H.
*some, means (about) a factor of ten in amplitude,
20 dB in power.

Huh? What will that do? Sounds like it would be even more dangerous. But it is only practical if galvanically isolated with a transformer. Then you can ground the dock to whatever you want and not worry about common mode transients.

--

Rick C.

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

 

[George Herold]

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

I'm late to reading any of this... seems to me the problem
is mostly associated with metal boat launches.... so maybe
some guide lines/ rules there.

(knowing almost nothing of power engineering),
Couldn't we make boat launches that floated the
ground some* DC to 60 Hz... and a few harmonics.?

George H.
*some, means (about) a factor of ten in amplitude,
20 dB in power.

 

[Phil Hobbs]

On 8/12/19 3:43 PM, Martin Brown wrote:

On 11/08/2019 21:32, 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.  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.

The strange thing is that despite using half the voltage in the US as
compared to the UK you electrocute a heck of a lot more people in the
home every year. By about two orders of magnitude today if the ONS
statistics and US electrocutions stats are to be believed.

https://www.rightdiagnosis.com/e/electrocution/stats.htm

https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=61494


UK is also mostly TN-S now although many homes also have a local earth
bond into the soil at the premises - a hangover from the original TT.
Our soil is really rather wet most of the time so it works quite well.

And at least some of those UK electrocutions are Darwin award candidates
balancing electric fires on the corner of their baths in winter.

We went round this mulberry bush here some months ago. Turns out that
per capita, slightly fewer folks die over here than OYOSTOP.

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

 

On Sun, 11 Aug 2019 12:29:07 -0700, Wolf Bagger <wolfbagger@pm.me>
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.

The soil must be very wet in UK and hence have a good conductivity to
allow the TT system work as intended.

Assuming the grounding resistance between house and distribution
transformer is as low as 10 ohms. A ground fault from 240 V will cause
a 24 A ground current. It takes a looong time (minutes) to blow even a
13 A fuse.

In practice RCDs must be used to disconnect the mains voltage fast
enough in case of a fault.

 

On Mon, 12 Aug 2019 22:52:43 -0700 (PDT), Rick C
<gnuarm.deletethisbit@gmail.com> wrote:

On Tuesday, August 13, 2019 at 12:28:53 AM UTC-4, upsid...@downunder.com wrote:
On Sun, 11 Aug 2019 12:29:07 -0700, Wolf Bagger <wolfbagger@pm.me
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.

The soil must be very wet in UK and hence have a good conductivity to
allow the TT system work as intended.

For one, that's an unfounded assumption since you can get adequate conductivity in poor locations, it just costs more. The other issue is that there are always variations. I seriously doubt the entire UK has the same soil.


Assuming the grounding resistance between house and distribution
transformer is as low as 10 ohms. A ground fault from 240 V will cause
a 24 A ground current. It takes a looong time (minutes) to blow even a
13 A fuse.

In practice RCDs must be used to disconnect the mains voltage fast
enough in case of a fault.

I'm confused. Isn't the neutral bonded to ground at both ends? Blowing a fuse on a ground fault is not why the neutral is grounded.

If the N and PE are both connected to a ground electrode, then N and
PE are also connected together. That sounds like a TN-C-S, in which
there is a shared PEN conductor from distribution transformer to house
and in the house the PEN is split to N and PE. The splitting point can
then be connected to a local grounding electrode, in case the PEN wire
is broken.

 

[Rick C]

On Tuesday, August 13, 2019 at 12:28:53 AM UTC-4, upsid...@downunder.com wrote:

On Sun, 11 Aug 2019 12:29:07 -0700, Wolf Bagger <wolfbagger@pm.me
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.

The soil must be very wet in UK and hence have a good conductivity to
allow the TT system work as intended.

For one, that's an unfounded assumption since you can get adequate conductivity in poor locations, it just costs more. The other issue is that there are always variations. I seriously doubt the entire UK has the same soil.

Assuming the grounding resistance between house and distribution
transformer is as low as 10 ohms. A ground fault from 240 V will cause
a 24 A ground current. It takes a looong time (minutes) to blow even a
13 A fuse.

In practice RCDs must be used to disconnect the mains voltage fast
enough in case of a fault.

I'm confused. Isn't the neutral bonded to ground at both ends? Blowing a fuse on a ground fault is not why the neutral is grounded.

--

Rick C.

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

 

[Martin Brown]

On 13/08/2019 06:52, Rick C wrote:

On Tuesday, August 13, 2019 at 12:28:53 AM UTC-4,
upsid...@downunder.com wrote:
On Sun, 11 Aug 2019 12:29:07 -0700, Wolf Bagger <wolfbagger@pm.me
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.

The soil must be very wet in UK and hence have a good conductivity
to allow the TT system work as intended.

Most regions of the UK get around 1m of rain per year. Some get more a
few get less. My top soil dries out in summer sometimes but the water
table is so high that the grounding rod goes deep into a permanent wet
clay soil. I have to siphon water out of my garage pit to use it.

Telecoms have problems with junction boxes here filling with water.

Dig down almost anywhere in the UK and you often find water filling your
trench. It makes water divining something of a doddle...

It rains enough that chemical corrosion of the grounding conductor is
probably more of a worry than it not making good electrical contact.

Assuming the grounding resistance between house and distribution
transformer is as low as 10 ohms. A ground fault from 240 V will
cause a 24 A ground current. It takes a looong time (minutes) to
blow even a 13 A fuse.

In practice RCDs must be used to disconnect the mains voltage fast
enough in case of a fault.

I'm confused. Isn't the neutral bonded to ground at both ends?
Blowing a fuse on a ground fault is not why the neutral is grounded.

New UK build is now mostly TN-C-S with neutral and earth combined but
where I live the distribution system is rural TT and in older homes the
older system was buried armoured cable with the steel sheath as pure
earth and separate live and neutral insulated cables inside it TN-S.
Made things safer if you put a spade through the buried cable.

Historically the UK kept protective earth and neutral distinct. You
could often measure a modest potential difference between neutral and
earth. I have seen my neutral rise quite a way from earth when a single
phase went down under a fault condition recently. LED bulbs, TV and
computers worked fine but classic filament bulbs glowed a dim orange.

--
Regards,
Martin Brown

 

[David Lesher]

Speaking of fish, the Pacific Intertie has ground grids at each
end in case they must dump a few gigawatts somewhere....

<https://en.wikipedia.org/wiki/Pacific_DC_Intertie#Components>
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[Whoey Louie]

On Monday, August 12, 2019 at 8:28:16 PM UTC-4, Rick C wrote:

On Monday, August 12, 2019 at 8:01:43 PM UTC-4, George Herold 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

I'm late to reading any of this... seems to me the problem
is mostly associated with metal boat launches.... so maybe
some guide lines/ rules there.

(knowing almost nothing of power engineering),
Couldn't we make boat launches that floated the
ground some* DC to 60 Hz... and a few harmonics.?

George H.
*some, means (about) a factor of ten in amplitude,
20 dB in power.

Huh? What will that do? Sounds like it would be even more dangerous. But it is only practical if galvanically isolated with a transformer. Then you can ground the dock to whatever you want and not worry about common mode transients.

--

Rick C.

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

More with the galvanic BS. No one in the code talks about "galvanic"
anything with regard to earthing.

This thread as usual has moved on to BS and the absurd. Those guys in
the article gave a solution. Disconnect the dock connection to the
equipment grounding conductor and use an earthing system at the dock
instead. Alternatively, you could just create an earthing electrode
system at the dock and tie it to the eqpt grounding conductor and that
would likely solve it too. Neither is code compliant.

 

On Tue, 13 Aug 2019 08:09:22 -0700 (PDT), Whoey Louie
<trader4@optonline.net> wrote:

On Monday, August 12, 2019 at 8:28:16 PM UTC-4, Rick C wrote:
On Monday, August 12, 2019 at 8:01:43 PM UTC-4, George Herold 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

I'm late to reading any of this... seems to me the problem
is mostly associated with metal boat launches.... so maybe
some guide lines/ rules there.

(knowing almost nothing of power engineering),
Couldn't we make boat launches that floated the
ground some* DC to 60 Hz... and a few harmonics.?

George H.
*some, means (about) a factor of ten in amplitude,
20 dB in power.

Huh? What will that do? Sounds like it would be even more dangerous. But it is only practical if galvanically isolated with a transformer. Then you can ground the dock to whatever you want and not worry about common mode transients.

--

Rick C.

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

More with the galvanic BS. No one in the code talks about "galvanic"
anything with regard to earthing.

Sounds like the IT system, As long as you have a ground on only one
phase, the system works normally. You just get an alarm of a ground
fault so it is a good idea to fix the ground fault before a ground
faults develops on an other phase.

Galvanic isolation is used with Safety Extra Low Voltage (SELV)
supplies (less than 50 Vac). Often required when working inside a
metallic tank.

This thread as usual has moved on to BS and the absurd. Those guys in
the article gave a solution. Disconnect the dock connection to the
equipment grounding conductor and use an earthing system at the dock
instead. Alternatively, you could just create an earthing electrode
system at the dock and tie it to the eqpt grounding conductor and that
would likely solve it too. Neither is code compliant.

 

[Bill Sloman]

On Monday, August 12, 2019 at 6:07:39 AM UTC+10, Cursitor Doom wrote:
> On Sun, 11 Aug 2019 10:17:18 -0700, Rick C wrote:

<snip>

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.

Cursitor Doom has clearly never tried to read E.C.Snelling on Soft Ferrites..

https://www.amazon.co.uk/Soft-Ferrites-Applications-C-Snelling/dp/0592027902

The grammar might have been okay, but it was a pedagogic disaster.

The main advantage that older text books have is that the junk never got reprinted, and the good stuff went through lots of editions.

And I do have to wonder what kinds of school Cursitor Doom thinks that I might approve of. I can't remember ever posting anything about schools here - beyond that universal education is a good thing, and that American primary and secondary schools have very variable funding from one school district to the next.

If the kids come out able to read, write and do arithmetic, the school has done it job, and the kids are in a state where they can learn more for themselves by reading books - if they are a bit brighter than Cursitor Doom and can recognise nonsense when they run into it (which he clearly can't) and can chuck the bad books.

--
Bill Sloman, Sydney