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Electric Shock Drowning: three more dead this week


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#1 DA-WOODY

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Posted 11 July 2012 - 02:33 PM

Posted Image

July10th

Electric Shock Drowning: three more dead this week



From the Ed's Friends at SAIL - http://www.sailfeed....-more-dead-week

I wrote a draft of this post last week, and wanted Kevin Ritz, President of the Electric Shock Drowning Prevention Association, to check its accuracy before going to press. In the interim three more children have died from Electric Shock Drowning (ESD).

I first became aware of ESD when I showed up for my first day at Kevin's ABYC Marine Electrical Certification course. After the first hour of class Kevin had us riveted, when we were all expecting a fairly dull week of electrical standards study. Kevin has dedicated his life to marine electrical safety because in 1999 his eight-year-old son Lucas died from ESD while swimming near their marina in Oregon. Kevin is a man on a mission and he tasked us with preventing ESD deaths in the future.

Kevin's challenge has been not only to improve safety, but to make the world understand this invisible killer. Often misidentified as simple drowning, ESD leaves no trace: it simply stops the heart and paralyzes the lungs. Sometimes, as with Kevin's son, the victim's head never even goes underwater. In ESD the heart's electrical signals are disrupted so badly that the victim often can't be revived, even using a defibrillator.

When a strong swimmer who hasn't been drinking suddenly drowns near a fresh water marina, ESD should always be suspected. It is coming to light that ESD is the cause of death in many more of these incidents than previously imagined.

Most victims are young, because young people are more likely to be frolicking in the water. And often the first victim is followed by a second, who jumps in the water to help someone who appears to be drowning.

At least fifty people have died in the US from ESD since the mid-eighties, when people like Kevin first started putting two and two together. This list in inconclusive, and the number is probably much higher, because implicating ESD is circumstantial.

Sea water is 300 times more conductive than fresh water. You'd think this would make sea water more dangerous, but just the opposite: Our bodies are saline--about the same conductivity as sea water--so in sea water we're nothing special. In fresh water, however, we are a little floating island of good conductivity in a sea of poor conductivity. Stray current tries to get back to its source by the path of least resistance, so it will "jump" through a saline human who swims in fresh water. It only takes a small voltage gradient in the water (as little as 2 volts per foot) to cause cardiac and respiratory paralysis.

Sometimes a marina's wiring is implicated, but more often the culprit is inadequate grounding or bonding aboard a boat combined with an errant AC connection to the surrounding water, usually via the propeller shaft or a thru-hull.

A solution? The ELCI, mentioned in a previous blog post, would have prevented almost all of these ESD accidents. New to the standard in the US, I've installed several ELCIs this year, and I'm recommending them to everyone.

If you are swimming and feel a tingling sensation or muscle paralysis, back up! The voltage gradient radiates from the current leak and increases as you get closer. Also, stay upright. Upright, in a treading water position, you cover only a few feet of voltage gradient, but by swimming horizontally you could worsen the situation by covering voltage gradients with the entire length of your body.

As electricians we have to be careful what we say, because any kind of electricity can be dangerous, but AC is the culprit in most marine electrical accidents, and AC systems are where most confusion lies. Marine AC wiring is NOT the same as shore-based AC wiring, and a land-trained electrician can make some terrible mistakes on a boat. If you're not completely sure what you're doing with AC, hire a professional. Most marine electricians can carry out a fairly thorough AC safety survey in less than an hour, which doesn't cost much, and most are happy to do this as a "public service."

You can learn more about ESD on the nascent website www.electricshockdrowning.org, and on the ESD Facebook page. You can read Kevin's story here.



#2 kent_island_sailor

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Posted 11 July 2012 - 03:00 PM

Anyone who does or did work underwater in marinas is very sensitive to people doing half-assed or quarter-assed wiring jobs because they "don't believe in connecting the grounds because uncle Billy said it would corrode something" and who wants to waste money on a galvanic isolator and all that crap when extension cords are $15 at Walmart :rolleyes: :angry:

#3 Barkley

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Posted 11 July 2012 - 03:17 PM

DaWoody, thank you for posting this. Given the risks, we should all spread the word.

#4 kent_island_sailor

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Posted 11 July 2012 - 03:21 PM

What they left out is it takes even less current to drown you than kill you outright. It disrupts your muscles so you can't swim. This is why I go in with a BC full and only let the air out if I don't get shocked ;)
*this after a story at an ABYC conference about a diver floating around and looking like a frog connected to a bug zapper while his buddies desperately ran around trying to shut the power off :o

#5 FastBottoms

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Posted 11 July 2012 - 03:35 PM

Anyone who does or did work underwater in marinas is very sensitive to people doing half-assed or quarter-assed wiring jobs...

100% true. However, almost all electric shock drownings occur in freshwater. Not nearly as much of a hazard in saltwater marinas.

#6 SEMIJim

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Posted 11 July 2012 - 04:27 PM

Anyone who does or did work underwater in marinas is very sensitive to people doing half-assed or quarter-assed wiring jobs...

*snort* After having spent a few years around sailboats, powerboats, sailors, people who think they're sailors, marinas, etc. I have come to the conclusion that sailors (or other boat people) and electrical stuff is a Bad Combination.

In this environment, I've seen very few full-assed wiring jobs, believe me.

...because ... who wants to waste money on a galvanic isolator and all that crap when extension cords are $15 at Walmart :rolleyes: :angry:

Here is a case where the marine industry is doing safety no favours.

Galvanic isolators are mind-bogglingly, stupidly priced. $150 or more for essentially a bridge rectifier (less than $10 at an electronics parts store), a hunk of aluminium, a bit of wire and some terminations. Give. Me. A. Break.

Marine ELCI? Oh boy. Essentially a marinized DPST GFCI. 240VAC 30A GFCI breaker at a big box store: About $70. Blue Sea's (not picking on them, they're just the easiest reference) lowest-end ELCI inna box is over $300 at a marine discounter.

Gee... I wonder why boaters don't run right out and buy this stuff?

ETA: I don't even want to think what a "marine electrician" would charge to install this stuff. (Do I sense a get-rich-quick job opportunity, here...?)

Jim

#7 Speedskater

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Posted 11 July 2012 - 05:13 PM

In an electrician's forum, a safety guy wrote:

Basically, it only takes about 2 volts per foot gradient in water to paralyze a swimmer, and that quickly leads to a drowning death. If you extend your hands out 5 feet, then the 10 volts from finger tip to finger tip can exceed 10 mA current through your body, which is enough to cause paralysis. This is why you can be shocked unconscious in the water even if you're not directly touching a conduit or electrical box with a hot-skin condition on a boat dock. This gradient field produced shock potential is mostly a freshwater problem and can extend out dozens feet from a dock or boat hooked to shore power. Under proper freshwater conductivity conditions a 120 volt potential hot-skin on a dock or boat could reach out 60 feet and still meet the 2 volt per foot gradient where a swimmer can be paralyzed and drown.

#8 SEMIJim

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Posted 11 July 2012 - 05:20 PM

That is fascinating, and very good, information, Speedskater. I don't know as I would've expected that kind large a hazard zone.

Btw, DA-WOODY, thanks for the PSA.

Jim

#9 One eye Jack

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Posted 11 July 2012 - 07:46 PM

This was happening back in the 60s.. People were for no reason drowning ..they found the culprit was using a car battery charger on boats...A battery charger for boats are wired differently than a car battery charger.. A car battery charger will emit an electrical voltage into the water ..they are a lot cheaper and more available to get..BUT THEY ARE KILLERS on any boat that is in the water when they are in use...and think of the amount of amperage that charger is putting out..it far exceeds any thing that harbor wiring can ...

#10 One eye Jack

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Posted 11 July 2012 - 07:52 PM

1342018856[/url]' post='3782354']
Anyone who does or did work underwater in marinas is very sensitive to people doing half-assed or quarter-assed wiring jobs because they "don't believe in connecting the grounds because uncle Billy said it would corrode something" and who wants to waste money on a galvanic isolator and all that crap when extension cords are $15 at Walmart :rolleyes: :angry:


I have seen where bigger boats come into a harbor that only has 30 amp boxes..one time ..let me see if this is right.. Hooked up his 60 amp boat by splitting the two legs of the plug and used the ground for the 3 rd leg..sound right? I'm not an electrician.. But he used the ground as part of the electrical circuit.. Putting an electrical current into the ground.

#11 tommays

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Posted 11 July 2012 - 08:24 PM

Only in the USA is to dangerous to NOT HAVE GFCIs anyplace at home remotely close to water and A OK for nothing at the Marina on the docks because nobody ever dropped a plugged in shorepower cord overboard before :(

And the ones hanging in the water never leak current :( :(

#12 Speedskater

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Posted 11 July 2012 - 08:48 PM

Link to a technical thread:

http://forums.mikeho...ad.php?t=146299

#13 R Booze

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Posted 11 July 2012 - 09:06 PM

Despite being in the construction biz for years & years, electrical shit is one thing that still worries me----which is why I only hired licensed sparkys. I first heard of this ESD crap happening about seven years ago and it has frightened the hell out of me ever since....'specially since we spend a lot of time in Mexico and a couple of other countries that haven't the building standards that we ('sposedly) have. Stopped letting the Kidz jump into the marinas down there....and sometimes the pools. But also I worry 'cuz I've been shocked/hurt several times in my life in rather odd ways;

1). 3-1/4 hp. non-insulated Rockwell router shorts out in my hands in high school. Buddy yells for shop teacher to come over as my hair stands up straight. He kicks me in the chest which sends me backwards, with head slamming into the 30' surface planer. Ouch.

2). Visiting my Dad when I was about 15 at the RV park in Capo Beach. He asks me to turn on the outside hose and water the veggie garden. Grab the hose bib and......zzzzzzzzzzz. Dad kicks me in the wrist to break my grip. Ouch 2.

3). Living in Cantamar, Baja, and go to our favorite local butcher shop. Walk in wearing go-heads, the floor has just been washed and soaking wet, cruise back to the meat counter, say Hi and place both arms on the glass & stainless display case. Zzzzzzzzzzzzz. Ouch 3.

4). Yucca Valley motel, pretty nice place, beautiful evening. Talk The Nurse into getting into the built in Jacooz with me. Grab the little safety rail, lean down, stick my foot in the water......and more fuking zzzzzzzzzzzz. Dammit.

5). Drove my Econoline pick-up thru a water puddle one night and stalled under the freeway. Lifted the metal engine covered, dried off the wires, dizzy cap & rotor. Resting right arm on air cleaner (and elbow on coil wire), hit ignition with left hand. Fuk me but that one hurt worse than all the others, even at 12 VDC.

6). Went to a couple's house years ago for an estimate----husband meets me at the door and starts showing me their kitchen. Wife walks in a few minutes later, elbows bent at 90 degrees, in 2 separate casts, forearms pointing straight up. She saw the look in my eye and explained what happened-----seems they just had new aluminum windows installed a few weeks earlier. She went to put in one of the screens and both elbow touched the frame. Which had a hundred and twenty volts going thru it, due to some bad contracting. Nice job there, idiots.

There's probably a few more that I'm forgetting, but you get the picture----me and electricity don't mix very well. Too bad my parents aren't around to tell me if the doc left a fucking meteorite in my head when I was born.....

#14 Guitar

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Posted 11 July 2012 - 09:35 PM

Great post Woodman. Front Page!!!

#15 CyberBOB

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Posted 11 July 2012 - 09:42 PM

Despite being in the construction biz for years & years, electrical shit is one thing that still worries me----which is why I only hired licensed sparkys. I first heard of this ESD crap happening about seven years ago and it has frightened the hell out of me ever since....'specially since we spend a lot of time in Mexico and a couple of other countries that haven't the building standards that we ('sposedly) have. Stopped letting the Kidz jump into the marinas down there....and sometimes the pools. But also I worry 'cuz I've been shocked/hurt several times in my life in rather odd ways;

1). 3-1/4 hp. non-insulated Rockwell router shorts out in my hands in high school. Buddy yells for shop teacher to come over as my hair stands up straight. He kicks me in the chest which sends me backwards, with head slamming into the 30' surface planer. Ouch.

2). Visiting my Dad when I was about 15 at the RV park in Capo Beach. He asks me to turn on the outside hose and water the veggie garden. Grab the hose bib and......zzzzzzzzzzz. Dad kicks me in the wrist to break my grip. Ouch 2.

3). Living in Cantamar, Baja, and go to our favorite local butcher shop. Walk in wearing go-heads, the floor has just been washed and soaking wet, cruise back to the meat counter, say Hi and place both arms on the glass & stainless display case. Zzzzzzzzzzzzz. Ouch 3.

4). Yucca Valley motel, pretty nice place, beautiful evening. Talk The Nurse into getting into the built in Jacooz with me. Grab the little safety rail, lean down, stick my foot in the water......and more fuking zzzzzzzzzzzz. Dammit.

5). Drove my Econoline pick-up thru a water puddle one night and stalled under the freeway. Lifted the metal engine covered, dried off the wires, dizzy cap & rotor. Resting right arm on air cleaner (and elbow on coil wire), hit ignition with left hand. Fuk me but that one hurt worse than all the others, even at 12 VDC.

6). Went to a couple's house years ago for an estimate----husband meets me at the door and starts showing me their kitchen. Wife walks in a few minutes later, elbows bent at 90 degrees, in 2 separate casts, forearms pointing straight up. She saw the look in my eye and explained what happened-----seems they just had new aluminum windows installed a few weeks earlier. She went to put in one of the screens and both elbow touched the frame. Which had a hundred and twenty volts going thru it, due to some bad contracting. Nice job there, idiots.

There's probably a few more that I'm forgetting, but you get the picture----me and electricity don't mix very well. Too bad my parents aren't around to tell me if the doc left a fucking meteorite in my head when I was born.....



Ouch. You seem to have bad luck with electricity.

And the electro-shcok therapy explains a lot ;)

#16 Bitter Gnat

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Posted 11 July 2012 - 10:13 PM

Is there some sort of detection device you can use to sniff problems out? I'd love to walk the docks in our little marina and check around all the boats I know are using car battery chargers on board.

#17 SEMIJim

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Posted 11 July 2012 - 10:15 PM

5). Drove my Econoline pick-up thru a water puddle one night and stalled under the freeway. Lifted the metal engine covered, dried off the wires, dizzy cap & rotor. Resting right arm on air cleaner (and elbow on coil wire), hit ignition with left hand. Fuk me but that one hurt worse than all the others, even at 12 VDC.

ROFL! That's because the output of an automotive ignition coil is more on the order of 20KV, not 12V. :lol:

Jim

#18 MoeAlfa

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Posted 11 July 2012 - 10:19 PM

Is there some sort of detection device you can use to sniff problems out? I'd love to walk the docks in our little marina and check around all the boats I know are using car battery chargers on board.


Tape the electrodes of your multi-meter to a forked stick, put them in the water, rotate through a few planes, and read the AC voltage.

#19 R Booze

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Posted 11 July 2012 - 10:23 PM


5). Drove my Econoline pick-up thru a water puddle one night and stalled under the freeway. Lifted the metal engine covered, dried off the wires, dizzy cap & rotor. Resting right arm on air cleaner (and elbow on coil wire), hit ignition with left hand. Fuk me but that one hurt worse than all the others, even at 12 VDC.

ROFL! That's because the output of an automotive ignition coil is more on the order of 20KV, not 12V. :lol:

Jim


So I should stay away from the 49K volt MSD's that I put on my Fords when it rains?..... :lol:

#20 One eye Jack

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Posted 11 July 2012 - 11:03 PM

1342042948[/url]' post='3782895']

1342040765[/url]' post='3782849']
Despite being in the construction biz for years & years, electrical shit is one thing that still worries me----which is why I only hired licensed sparkys. I first heard of this ESD crap happening about seven years ago and it has frightened the hell out of me ever since....'specially since we spend a lot of time in Mexico and a couple of other countries that haven't the building standards that we ('sposedly) have. Stopped letting the Kidz jump into the marinas down there....and sometimes the pools. But also I worry 'cuz I've been shocked/hurt several times in my life in rather odd ways;

1). 3-1/4 hp. non-insulated Rockwell router shorts out in my hands in high school. Buddy yells for shop teacher to come over as my hair stands up straight. He kicks me in the chest which sends me backwards, with head slamming into the 30' surface planer. Ouch.

2). Visiting my Dad when I was about 15 at the RV park in Capo Beach. He asks me to turn on the outside hose and water the veggie garden. Grab the hose bib and......zzzzzzzzzzz. Dad kicks me in the wrist to break my grip. Ouch 2.

3). Living in Cantamar, Baja, and go to our favorite local butcher shop. Walk in wearing go-heads, the floor has just been washed and soaking wet, cruise back to the meat counter, say Hi and place both arms on the glass & stainless display case. Zzzzzzzzzzzzz. Ouch 3.

4). Yucca Valley motel, pretty nice place, beautiful evening. Talk The Nurse into getting into the built in Jacooz with me. Grab the little safety rail, lean down, stick my foot in the water......and more fuking zzzzzzzzzzzz. Dammit.

5). Drove my Econoline pick-up thru a water puddle one night and stalled under the freeway. Lifted the metal engine covered, dried off the wires, dizzy cap & rotor. Resting right arm on air cleaner (and elbow on coil wire), hit ignition with left hand. Fuk me but that one hurt worse than all the others, even at 12 VDC.

6). Went to a couple's house years ago for an estimate----husband meets me at the door and starts showing me their kitchen. Wife walks in a few minutes later, elbows bent at 90 degrees, in 2 separate casts, forearms pointing straight up. She saw the look in my eye and explained what happened-----seems they just had new aluminum windows installed a few weeks earlier. She went to put in one of the screens and both elbow touched the frame. Which had a hundred and twenty volts going thru it, due to some bad contracting. Nice job there, idiots.

There's probably a few more that I'm forgetting, but you get the picture----me and electricity don't mix very well. Too bad my parents aren't around to tell me if the doc left a fucking meteorite in my head when I was born.....



Ouch. You seem to have bad luck with electricity.

And the electro-shcok therapy explains a lot ;)


Getting some guy that tells you they are electricians are bad enough.. But some of these 3rd world guys will Absolutly shock you with their electrical work.. The Army Lost 4 or 5 guys in Iraq from bad wiring..one went to take a shower, one was using a pressure washer to knock off the mud on a humvee. Can't remember the rest.. But like your stories..it is getting to be a common practice..Somebody at the Santa Cruz,Ca harbor did a test one day with aluminum cans.. The one inside the harbor was gone in about a week.. The one that he placed in the bay lasted weeks...and think what happens to your zinks.I have even heard that your carbon fiber hull will attract wayward electrical currents.

#21 Steam Flyer

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Posted 11 July 2012 - 11:57 PM

Does anybody have a technical reference on how to find & diagnose stray current in the water around docks? I looked at the links given above and found a bunch of empty pages and one in Latin. Very erudite but not particularly helpful.

TIA

FB- Doug

#22 stranded

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Posted 12 July 2012 - 12:20 AM

a plug in earth leakage tripper at the shore outlet will tell you when things are bad

#23 R Booze

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Posted 12 July 2012 - 12:25 AM

And what if you're on the hook somewhere, with the big-assed genny running?....

#24 Cavelamb

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Posted 12 July 2012 - 12:33 AM

This was happening back in the 60s.. People were for no reason drowning ..they found the culprit was using a car battery charger on boats...A battery charger for boats are wired differently than a car battery charger.. A car battery charger will emit an electrical voltage into the water ..they are a lot cheaper and more available to get..BUT THEY ARE KILLERS on any boat that is in the water when they are in use...and think of the amount of amperage that charger is putting out..it far exceeds any thing that harbor wiring can ...


I'm calling BS.

Unless you can cite something more substantial.

#25 MoeAlfa

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Posted 12 July 2012 - 12:48 AM

Does anybody have a technical reference on how to find & diagnose stray current in the water around docks? I looked at the links given above and found a bunch of empty pages and one in Latin. Very erudite but not particularly helpful.

TIA

FB- Doug

See post 18. A gradient of 2 V/ft. is easily detectable and any current is irrelevant, inasmuch as the only one that matters in human safety terms is the one going through your body.

#26 One eye Jack

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Posted 12 July 2012 - 01:23 AM

1342053186[/url]' post='3783091']

1342036002[/url]' post='3782734']
This was happening back in the 60s.. People were for no reason drowning ..they found the culprit was using a car battery charger on boats...A battery charger for boats are wired differently than a car battery charger.. A car battery charger will emit an electrical voltage into the water ..they are a lot cheaper and more available to get..BUT THEY ARE KILLERS on any boat that is in the water when they are in use...and think of the amount of amperage that charger is putting out..it far exceeds any thing that harbor wiring can ...


I'm calling BS.

Unless you can cite something more substantial.


Go troll someplace else..people are be electrocuted by this and you want to add drivel.

#27 MSA

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Posted 12 July 2012 - 01:23 AM


Anyone who does or did work underwater in marinas is very sensitive to people doing half-assed or quarter-assed wiring jobs...

*snort* After having spent a few years around sailboats, powerboats, sailors, people who think they're sailors, marinas, etc. I have come to the conclusion that sailors (or other boat people) and electrical stuff is a Bad Combination.

In this environment, I've seen very few full-assed wiring jobs, believe me.

...because ... who wants to waste money on a galvanic isolator and all that crap when extension cords are $15 at Walmart :rolleyes: :angry:

Here is a case where the marine industry is doing safety no favours.

Galvanic isolators are mind-bogglingly, stupidly priced. $150 or more for essentially a bridge rectifier (less than $10 at an electronics parts store), a hunk of aluminium, a bit of wire and some terminations. Give. Me. A. Break.

Marine ELCI? Oh boy. Essentially a marinized DPST GFCI. 240VAC 30A GFCI breaker at a big box store: About $70. Blue Sea's (not picking on them, they're just the easiest reference) lowest-end ELCI inna box is over $300 at a marine discounter.

Gee... I wonder why boaters don't run right out and buy this stuff?

ETA: I don't even want to think what a "marine electrician" would charge to install this stuff. (Do I sense a get-rich-quick job opportunity, here...?)

Jim


Complaining about the cost of a safety item is not the right attitude.. Marine stuff is expensive.. Cough up what it costs or stick to racing Billy carts down your local grass hill.

The problem is we have an unregulated industry. There are attempts to regulate it but nothing is actually what I would call the equivalent of the Car manufacturing industry.

And its not just Sailing. Any small volume item anywhere in the world with be expensive, relative to High volume products..

#28 Cheesy

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Posted 12 July 2012 - 02:18 AM


This was happening back in the 60s.. People were for no reason drowning ..they found the culprit was using a car battery charger on boats...A battery charger for boats are wired differently than a car battery charger.. A car battery charger will emit an electrical voltage into the water ..they are a lot cheaper and more available to get..BUT THEY ARE KILLERS on any boat that is in the water when they are in use...and think of the amount of amperage that charger is putting out..it far exceeds any thing that harbor wiring can ...


I'm calling BS.

Unless you can cite something more substantial.


I think you will find that most automotive battery chargers only have a half bridge rectifier in them so there is still an AC component which is now connected to you engine/sail drive etc through the 12v wiring. Easy to check, plug in your charger and you should get approx 14v with a multi meter on DC, now switch the meter to AC and you will get a reading...

#29 CarbonComposite

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Posted 12 July 2012 - 05:49 AM

Not only marine environments. Should you find yourself in the vicinity of a live downed power line, move away by taking very small steps, or even hopping on one foot. do not bridge large power gradients with conducing body parts.

#30 kent_island_sailor

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Posted 12 July 2012 - 11:32 AM

Where I live the water can be fresh one day and salty another day. Depends on the tide, time of year, and recent rainfall. I once got shocked real good when I was standing on a floating dock and the air conditioning switched on aboard the boat I was about to get aboard. The discharge water was zapping me but good :o Turns out the green and white wires had been switched when the air conditioning was installed :angry:

As for automotive battery chargers, YMMV. Some of them are fine and some are really crappy chargers. What matters as far as danger to others is the isolation between the AC and DC side. You might find one with an autotransformer or some other cheap-ass arrangement that allows the shore power side access to the DC side.

I don't have time to write a long article on DC and AC grounding right now, but if you don't have a real shore power setup on your boat and need to run a cord for some work, PLEASE get one of those "construction" GFCI outlets like this one to plug into the dock outlet and run your cord from there. It will trip if any dangerous (to swimmers or YOU) leakage occurs.

#31 GybeSetŪ

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Posted 12 July 2012 - 11:44 AM

Is there some sort of detection device you can use to sniff problems out?


the no cost option is to get your OETS and dip that in the tide




#32 Vorwaerts

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Posted 12 July 2012 - 12:06 PM

Where I live the water can be fresh one day and salty another day. Depends on the tide, time of year, and recent rainfall. I once got shocked real good when I was standing on a floating dock and the air conditioning switched on aboard the boat I was about to get aboard. The discharge water was zapping me but good :o Turns out the green and white wires had been switched when the air conditioning was installed :angry:

As for automotive battery chargers, YMMV. Some of them are fine and some are really crappy chargers. What matters as far as danger to others is the isolation between the AC and DC side. You might find one with an autotransformer or some other cheap-ass arrangement that allows the shore power side access to the DC side.

I don't have time to write a long article on DC and AC grounding right now, but if you don't have a real shore power setup on your boat and need to run a cord for some work, PLEASE get one of those "construction" GFCI outlets like this one to plug into the dock outlet and run your cord from there. It will trip if any dangerous (to swimmers or YOU) leakage occurs.


Are GFCIs not integrated in every power socket placed outside (in general all low voltage installations should be protected by one)? Typically the will shut the power off if there is more than 30 mA current difference. I can not remember a marina power socket without the typical test button which are integrated in GFCIs. That should in theory solve a lot of problems.

#33 Sailabout

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Posted 12 July 2012 - 12:38 PM

put your clamp meter on the shore power cable and it should read zero if not something is going somewhere else..

#34 kent_island_sailor

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Posted 12 July 2012 - 12:40 PM

I have never ever seen a shore power outlet with a GFCI and frequently that is all you have. At my last marine they did have a few 15 amp outlets and they were not GFCIs either.


Where I live the water can be fresh one day and salty another day. Depends on the tide, time of year, and recent rainfall. I once got shocked real good when I was standing on a floating dock and the air conditioning switched on aboard the boat I was about to get aboard. The discharge water was zapping me but good :o Turns out the green and white wires had been switched when the air conditioning was installed :angry:

As for automotive battery chargers, YMMV. Some of them are fine and some are really crappy chargers. What matters as far as danger to others is the isolation between the AC and DC side. You might find one with an autotransformer or some other cheap-ass arrangement that allows the shore power side access to the DC side.

I don't have time to write a long article on DC and AC grounding right now, but if you don't have a real shore power setup on your boat and need to run a cord for some work, PLEASE get one of those "construction" GFCI outlets like this one to plug into the dock outlet and run your cord from there. It will trip if any dangerous (to swimmers or YOU) leakage occurs.


Are GFCIs not integrated in every power socket placed outside (in general all low voltage installations should be protected by one)? Typically the will shut the power off if there is more than 30 mA current difference. I can not remember a marina power socket without the typical test button which are integrated in GFCIs. That should in theory solve a lot of problems.



#35 Vorwaerts

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Posted 12 July 2012 - 01:02 PM

I have never ever seen a shore power outlet with a GFCI and frequently that is all you have. At my last marine they did have a few 15 amp outlets and they were not GFCIs either.


Having GFCIs in power outlets must be an European thing then?

#36 islanderboy32

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Posted 12 July 2012 - 01:03 PM

You can test the basic situation in a marina with your multimeter - one probe in the ground contact of an outlet on the pier, the other dropped in the water. Current and voltage should both be zero. Any reading indicates a ground fault issue somewhere fairly close. My club spent large $$ on a new floating marina, was the first thing I did in the slip first day.

#37 MoeAlfa

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Posted 12 July 2012 - 01:23 PM

You can test the basic situation in a marina with your multimeter - one probe in the ground contact of an outlet on the pier, the other dropped in the water. Current and voltage should both be zero. Any reading indicates a ground fault issue somewhere fairly close. My club spent large $ on a new floating marina, was the first thing I did in the slip first day.

That tests one outlet. Doesn't it make more sense to look for a field in the water, if you're not concerned about a particular source?

#38 kent_island_sailor

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Posted 12 July 2012 - 02:00 PM

Not so.
You are looking for voltage between the green wire ground, which is easy to get at by sticking a probe into the ground connection of the outlet, and various points in the water.



You can test the basic situation in a marina with your multimeter - one probe in the ground contact of an outlet on the pier, the other dropped in the water. Current and voltage should both be zero. Any reading indicates a ground fault issue somewhere fairly close. My club spent large $ on a new floating marina, was the first thing I did in the slip first day.

That tests one outlet. Doesn't it make more sense to look for a field in the water, if you're not concerned about a particular source?

Attached Files



#39 SEMIJim

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Posted 12 July 2012 - 02:01 PM

That tests one outlet. Doesn't it make more sense to look for a field in the water, if you're not concerned about a particular source?

You're concerned about the water being energized. All you need is one probe on a known good ground, and another in the water.

Personally, if there was nearby soil, as there is in most of my club's marina areas, I'd make myself a ground rod that wouldn't be likely to punch through underground wiring, sprinkler lines or what-have-you, and use that as my ground reference.

Jim

#40 SEMIJim

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Posted 12 July 2012 - 02:13 PM

Complaining about the cost of a safety item is not the right attitude.. Marine stuff is expensive..

So we should just bend over, because it's "marine?"

I don't think so.

The $300 ELCI box might almost be understandable, but the equivalent of a $10 bridge rectifier becoming a $150-$200 galvanic isolator?

Going by your reasoning, I should bring our 1976 boat up to current ABYC safety standards by spending $450-$600 on an ELCI box and galvanic isolator. If I had money to burn I wouldn't think twice about it. But I don't. If I thought that was really necessary, I'd dump shore power entirely, first. But my bigger point was: I understand the desirability of such safety measures, and I'm generally a cautious kind of guy. So if I'm disinclined to spend that kind of money (and remember: I wouldn't have to hire somebody to properly install that stuff), what does that say about the likelihood of wider adoption?

Jim

#41 MoeAlfa

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Posted 12 July 2012 - 03:20 PM

Not so.
You are looking for voltage between the green wire ground, which is easy to get at by sticking a probe into the ground connection of the outlet, and various points in the water.




You can test the basic situation in a marina with your multimeter - one probe in the ground contact of an outlet on the pier, the other dropped in the water. Current and voltage should both be zero. Any reading indicates a ground fault issue somewhere fairly close. My club spent large $ on a new floating marina, was the first thing I did in the slip first day.

That tests one outlet. Doesn't it make more sense to look for a field in the water, if you're not concerned about a particular source?

True enough, if you know that ground is actually at zero. I would maintain that fields much less intense than that mentioned above as lethal (2V/ft) would be very easy to measure between two closely spaced points in the water in any area you were concerned about.

If I'm wrong, please educate me.

#42 Speedskater

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Posted 12 July 2012 - 04:18 PM

Does anybody have a technical reference on how to find & diagnose stray current in the water around docks? I looked at the links given above and found a bunch of empty pages and one in Latin. Very erudite but not particularly helpful.
TIA
FB- Doug


They are working on it. See the last posts.

http://forums.mikeholt.com/showthread.php?t=146299

#43 kent_island_sailor

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Posted 12 July 2012 - 04:33 PM

You would have to take some PVC pipe or something and make a "probe spacer", but that would work too.


Not so.
You are looking for voltage between the green wire ground, which is easy to get at by sticking a probe into the ground connection of the outlet, and various points in the water.




You can test the basic situation in a marina with your multimeter - one probe in the ground contact of an outlet on the pier, the other dropped in the water. Current and voltage should both be zero. Any reading indicates a ground fault issue somewhere fairly close. My club spent large $ on a new floating marina, was the first thing I did in the slip first day.

That tests one outlet. Doesn't it make more sense to look for a field in the water, if you're not concerned about a particular source?

True enough, if you know that ground is actually at zero. I would maintain that fields much less intense than that mentioned above as lethal (2V/ft) would be very easy to measure between two closely spaced points in the water in any area you were concerned about.

If I'm wrong, please educate me.



#44 luminary

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Posted 12 July 2012 - 04:46 PM

Not only marine environments. Should you find yourself in the vicinity of a live downed power line, move away by taking very small steps, or even hopping on one foot. do not bridge large power gradients with conducing body parts.


oh! right. thx.

#45 my nuts

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Posted 12 July 2012 - 04:58 PM


Not so.
You are looking for voltage between the green wire ground, which is easy to get at by sticking a probe into the ground connection of the outlet, and various points in the water.




You can test the basic situation in a marina with your multimeter - one probe in the ground contact of an outlet on the pier, the other dropped in the water. Current and voltage should both be zero. Any reading indicates a ground fault issue somewhere fairly close. My club spent large $ on a new floating marina, was the first thing I did in the slip first day.

That tests one outlet. Doesn't it make more sense to look for a field in the water, if you're not concerned about a particular source?

True enough, if you know that ground is actually at zero. I would maintain that fields much less intense than that mentioned above as lethal (2V/ft) would be very easy to measure between two closely spaced points in the water in any area you were concerned about.

If I'm wrong, please educate me.

while I agree in principle with Moe, I'd change the methodology slightly. the impedance of a multimeter probe relative the the interface with water may be too high to get a useable reading. this would be classified as an electrode of the first kind. what you want is an electrode of the second kind with a salt interface. so, if you can get your hands on some ECG (or EEG in your case) leads, they would be much more sensitive, as the Ag/AgCl electrode will be much more sensitive. as an alternative, you can lower the interface impedance by using bigger hunks of metal.

I do agree with the point regarding the testing of one outlet. Unless you're 100% sure that the ground of the outlet that you're testing is connected properly to the rest of the pier, representing a true ground, I would not entirely confident in the results of that test. further, see above regarding multimeter probe impedance in water.

#46 MoeAlfa

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Posted 12 July 2012 - 04:59 PM

You would have to take some PVC pipe or something and make a "probe spacer", but that would work too.



Not so.
You are looking for voltage between the green wire ground, which is easy to get at by sticking a probe into the ground connection of the outlet, and various points in the water.




You can test the basic situation in a marina with your multimeter - one probe in the ground contact of an outlet on the pier, the other dropped in the water. Current and voltage should both be zero. Any reading indicates a ground fault issue somewhere fairly close. My club spent large $ on a new floating marina, was the first thing I did in the slip first day.

That tests one outlet. Doesn't it make more sense to look for a field in the water, if you're not concerned about a particular source?

True enough, if you know that ground is actually at zero. I would maintain that fields much less intense than that mentioned above as lethal (2V/ft) would be very easy to measure between two closely spaced points in the water in any area you were concerned about.

If I'm wrong, please educate me.

That was the idea and your reach wouldn't be limited by being wired to an outlet.

#47 DA-WOODY

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Posted 12 July 2012 - 09:37 PM

topping up house Batts in me Motor Home

I pull out the Multi-Meter and find testing the Batt Posts while charging w a rolling Auto Charger

15.9V-DC & 4V-AC Posted Image Posted Image Posted Image Posted Image


that AC can't help fill a DC Batt ???????

and dunno how it could make any diff on a Boat if running off boat/Gen power = Not connected to Earth ground

Just trying to figure this out as I play in water all the time all year

#48 MoeAlfa

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Posted 12 July 2012 - 09:54 PM

topping up house Batts in me Motor Home

I pull out the Multi-Meter and find testing the Batt Posts while charging w a rolling Auto Charger

15.9V-DC & 4V-AC Posted Image Posted Image Posted Image Posted Image


that AC can't help fill a DC Batt ???????

and dunno how it could make any diff on a Boat if running off boat/Gen power = Not connected to Earth ground

Just trying to figure this out as I play in water all the time all year

In some chargers, I understand the monitoring gizmotics inject an AC component across the battery. Perhaps an expert can confirm or deny.

#49 Sailabout

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Posted 13 July 2012 - 12:32 AM

its just poor rectification

#50 SEMIJim

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Posted 13 July 2012 - 03:07 AM

topping up house Batts in me Motor Home

I pull out the Multi-Meter and find testing the Batt Posts while charging w a rolling Auto Charger

15.9V-DC & 4V-AC Posted Image Posted Image Posted Image Posted Image


that AC can't help fill a DC Batt ???????

Probably just DC ripple. The output of an automotive/marine battery charging system doesn't need to be squeaky clean ;)

Jim

#51 Dawg Gonit

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Posted 13 July 2012 - 03:38 AM

Electrical Engineers are gods.

I love Tesla. I read a biography, what a Genius. We are still using his principals today. Kind of tells you how far the human race has come in the last 120 years (not far).

#52 SEMIJim

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Posted 13 July 2012 - 12:50 PM

Electrical Engineers are gods.

LOL! Well, they'd certainly like you to think so. Or wizards, at least :)

"Any sufficiently advanced technology is indistinguishable from magic." - Arthur C. Clarke

To somebody who does not understand how electricity works, I guess it's an "advanced technology" ;)

Jim

#53 my nuts

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Posted 13 July 2012 - 01:40 PM

Electrical Engineers are gods.

I love Tesla. I read a biography, what a Genius. We are still using his principals today. Kind of tells you how far the human race has come in the last 120 years (not far).

now I don't have to add the "bow" qualifier anymore? sweet!

Tesla was a great innovator, but you should look into the contributions of Faraday, Gauss, Maxwell, Ampere, and Volta. without their work on the fundamental underpinnings of electricity, none of this stuff would exist.

#54 Timo42

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Posted 13 July 2012 - 02:06 PM


Electrical Engineers are gods.

LOL! Well, they'd certainly like you to think so. Or wizards, at least :)

"Any sufficiently advanced technology is indistinguishable from magic." - Arthur C. Clarke

To somebody who does not understand how electricity works, I guess it's an "advanced technology" ;)

Jim



You guys trying to bait DT?:blink:

I've seen more halfassed wiring on old boats than in any car, a buddy's boat was a candidate for "There I fixed it" when he bought it, and it isn't much better now. :o And he is a former a&p mechanic working as a residential electrician. :huh: When you can get a 2 bank marine charger for $150, I don't understand the use of car chargers.

#55 kgw

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Posted 13 July 2012 - 03:38 PM

Could you describe the "forked stick" in more detail? :blink:


Is there some sort of detection device you can use to sniff problems out? I'd love to walk the docks in our little marina and check around all the boats I know are using car battery chargers on board.


Tape the electrodes of your multi-meter to a forked stick, put them in the water, rotate through a few planes, and read the AC voltage.



#56 SEMIJim

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Posted 13 July 2012 - 04:39 PM

You guys trying to bait DT?:blink:

Dunno who "DT" is, but... sure, why not? :P

I've seen more halfassed wiring on old boats than in any car, a buddy's boat was a candidate for "There I fixed it" when he bought it, and it isn't much better now. :o And he is a former a&p mechanic working as a residential electrician. :huh: When you can get a 2 bank marine charger for $150, I don't understand the use of car chargers.

There's some of that on Abracadabra. The embarrassing part is: I'm an electrical/electronics/radio/computer guy, we've had her for five years, and I haven't fixed it yet.

It happens. "The cobbler's children go unshod" is the old saying.

Not any more, tho. Recently the depth sounder stopped sounding. Turned out it was nothing more than whomever had installed the in-hull transducer having neglected to put the o-ring in, so all the mineral oil slowly dribbled out. That's something I would've caught if I'd taken the time to address the excess sounder cable laying loosely in the space under the v-berth--just waiting for some errant piece of equipment to snag it and shag it. But the boat's an hour away, there's only so much time in the world and, well, we kind of like spending boat time, you know, boating. The good part is that was a minor, easily-fixable thing that was a wake up call to tell me "FIX THIS SH*T, before Something Important breaks at A Really Bad Time."

Jim

#57 kent_island_sailor

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Posted 13 July 2012 - 04:53 PM

You need electrodes spaced out a foot or two. What you are measuring is the volts per foot gradient.

BTW, D(tee) is like Voldem*rt - name him at your peril :o :o


Could you describe the "forked stick" in more detail? :blink:



Is there some sort of detection device you can use to sniff problems out? I'd love to walk the docks in our little marina and check around all the boats I know are using car battery chargers on board.


Tape the electrodes of your multi-meter to a forked stick, put them in the water, rotate through a few planes, and read the AC voltage.



#58 R Booze

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Posted 13 July 2012 - 05:02 PM

Do NOT say his name three times, whilst clicking your heels.....

#59 CyberBOB

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Posted 14 July 2012 - 12:36 AM

Electrical Engineers are gods.

I love Tesla. I read a biography, what a Genius. We are still using his principals today. Kind of tells you how far the human race has come in the last 120 years (not far).


I don't know about that, Dawg. I once worked with an electrical engineer. She went out and bought herself a new car. A few weeks later, she came in to work late, apologizing profusely. She said her car was dead, and she needed to buy a new one. We asked her if it was maybe a dead battery, and had she left anything on. She claimed it couldn't be a dead battery. We asked her again if she left anything on. She said just her dome light, but that couldn't have done anything because "the dome light wouldn't be connected to the battery"!!!

Don't get me wrong, there are some amazing electrical engineers, but certainly not all of them.

#60 SEMIJim

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Posted 14 July 2012 - 03:50 PM

I don't know about that, Dawg. I once worked with an electrical engineer. She went out and bought herself a new car. A few weeks later, she came in to work late, apologizing profusely. She said her car was dead, and she needed to buy a new one. We asked her if it was maybe a dead battery, and had she left anything on. She claimed it couldn't be a dead battery. We asked her again if she left anything on. She said just her dome light, but that couldn't have done anything because "the dome light wouldn't be connected to the battery"!!!

Don't get me wrong, there are some amazing electrical engineers, but certainly not all of them.

LOL!

Reminds me of an "engineer" that worked where I used to. Seriously hawt Asian babe. One day, while a bunch of us were heating our lunches in the microwaves, she kept putting hers in the microwave, zapping it, checking to see if it was hot, yet, finding it was not, putting it back in, zapping it some more, wash, rinse, repeat. Meanwhile, others were standing around waiting to use the microwaves. Finally, after the Nth iteration of her doing this, I spoke up "You know, if you leave the lid on loosely, more moisture is retained by what you're trying to heat, and it'll heat faster. If there's not much moisture in there, adding a bit will speed it up." She looked at me disdainfully and asks "Really?" "Yeah," I replied, and briefly explained how microwave ovens worked. She looked at me as if I'd just said the most nonsensical thing she'd ever heard, and kept on doing what she'd been doing. I looked at the other engineers in disbelief to find them doing the looking-around-at-the-ceiling-and-whistling thing. Later on one of them informed me it was commonly believed in the department that the hot Asian babe "engineer" was primarily eye candy for visiting customers--the vast majority of whom were male. They let her do the impromptu presentations.

She was a goddess, all right, but not an engineering goddess ;)

Jim

#61 tommays

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Posted 14 July 2012 - 04:27 PM

While i do not have shorepower I do understand how to do the ground correctly to the battery

I kind of understand how connecting and AC ground to battery might make it safer for the people on the boat in a failure mode BUT do not see how that makes it safer for people in the water ?

#62 R Booze

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Posted 14 July 2012 - 04:34 PM

While i do not have shorepower I do understand how to do the ground correctly to the battery

I kind of understand how connecting and AC ground to battery might make it safer for the people on the boat in a failure mode BUT do not see how that makes it safer for people in the water ?



AC ground to negative on battery to engine block ground to tranny to prop shaft to prop to open water? Any stray AC current/short circuit gets spit out the prop and into the surrounding waters?

(I don't know, I'm just a f'ng carpenter)......

#63 SEMIJim

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Posted 14 July 2012 - 05:03 PM

I kind of understand how connecting and AC ground to battery might make it safer for the people on the boat in a failure mode BUT do not see how that makes it safer for people in the water ?

Assuming vessel's metal bits that are in the water (prop shaft, metallic through-hulls, etc.) are all bonded together and the vessel's DC "return" (nearly always battery negative in this day-and-age) is connected to that: Should shorepower AC "hot" become connected to the DC return, the water will be energized. If the shorepower AC earth/safety ground is bonded to the boat's "ground" system, and the AC hot becomes connected to it, the shorepower breaker should trip. That of course assumes the shorepower ground is actually connected to ground.

Jim

#64 歐開倫

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Posted 14 July 2012 - 05:22 PM


Electrical Engineers are gods.

I love Tesla. I read a biography, what a Genius. We are still using his principals today. Kind of tells you how far the human race has come in the last 120 years (not far).

now I don't have to add the "bow" qualifier anymore? sweet!

Tesla was a great innovator, but you should look into the contributions of Faraday, Gauss, Maxwell, Ampere, and Volta. without their work on the fundamental underpinnings of electricity, none of this stuff would exist.


Sounds like a law firm!

#65 R Booze

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Posted 14 July 2012 - 05:25 PM



Electrical Engineers are gods.

I love Tesla. I read a biography, what a Genius. We are still using his principals today. Kind of tells you how far the human race has come in the last 120 years (not far).

now I don't have to add the "bow" qualifier anymore? sweet!

Tesla was a great innovator, but you should look into the contributions of Faraday, Gauss, Maxwell, Ampere, and Volta. without their work on the fundamental underpinnings of electricity, none of this stuff would exist.


Sounds like a law firm!


I think they actually all work for one Mr. Ohm....

#66 my nuts

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Posted 14 July 2012 - 07:20 PM



Electrical Engineers are gods.

I love Tesla. I read a biography, what a Genius. We are still using his principals today. Kind of tells you how far the human race has come in the last 120 years (not far).

now I don't have to add the "bow" qualifier anymore? sweet!

Tesla was a great innovator, but you should look into the contributions of Faraday, Gauss, Maxwell, Ampere, and Volta. without their work on the fundamental underpinnings of electricity, none of this stuff would exist.


Sounds like a law firm!

Ha! yes, they all have laws named after them (as does Ohm). and importantly, Maxwell's laws are the first set that formally linked two fundamental forces of nature, electric and magnetic. Without this linking, we would not have generators or motors or any telecommunications.

#67 R Booze

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Posted 14 July 2012 - 08:48 PM




Electrical Engineers are gods.

I love Tesla. I read a biography, what a Genius. We are still using his principals today. Kind of tells you how far the human race has come in the last 120 years (not far).

now I don't have to add the "bow" qualifier anymore? sweet!

Tesla was a great innovator, but you should look into the contributions of Faraday, Gauss, Maxwell, Ampere, and Volta. without their work on the fundamental underpinnings of electricity, none of this stuff would exist.


Sounds like a law firm!

Ha! yes, they all have laws named after them (as does Ohm). and importantly, Maxwell's laws are the first set that formally linked two fundamental forces of nature, electric and magnetic. Without this linking, we would not have generators or motors or any telecommunications.



Thank gawd he discovered that one, or we'd still have zillions of frustrated, 'hysterical' women roaming the planet....

#68 MoeAlfa

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Posted 14 July 2012 - 09:18 PM

You need electrodes spaced out a foot or two. What you are measuring is the volts per foot gradient.

BTW, D(tee) is like Voldem*rt - name him at your peril :o :o



Could you describe the "forked stick" in more detail? :blink:



Is there some sort of detection device you can use to sniff problems out? I'd love to walk the docks in our little marina and check around all the boats I know are using car battery chargers on board.


Tape the electrodes of your multi-meter to a forked stick, put them in the water, rotate through a few planes, and read the AC voltage.

Nah. Apparently, 2 V/foot can be lethal. That's 500 mV over 3"! Anything on that order of magnitude ought to be easily measurable even with a crappy meter.

#69 clarkbeek

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Posted 17 July 2012 - 06:53 PM

Hi, I wrote the original post, but just discovered this thread and joined Sailing Anarchy.

Kent_Island_Sailor is right, most of the time with Electric Shock Drowning it's muscle paralysis that disables the victim, and they drown. I screwed up, and this definition (the muscle paralysis one) is the common definition of ESD. We went over so many cases where the voltage differential was so pronounced that it just stopped the victim's heart, that I thought this was what always happened.

I agree that this stuff is expensive, but we marine electricians aren't getting rich installing galvanic isolators and ELCIs! Call it $450 in materials for a basic 30 Amp ELCI and galvanic isolator. It's very quick install on both of these, 1-2 hours, so not much billable time, and nobody every makes money off a job that's only 1-2 hours. And it's an Internet buying world now, so nobody makes much markup and parts either. Installing ELCIs is more of a public service.

My boat doesn't have either an ELCI or galvanic isolator, but it hasn't been plugged into shore power for about 12 years. The only AC I have is a portable inverter, and there's a reasonable argument for not having AC on a boat at all, but that's probably not for those of you who live where you'd suffocate without air conditioning.

Excuse me if this has been addressed before, but the done thing to check for leaks is clamping your shore power cord. You put an amp clamp around the whole cord (this is not how we're taught to use amp clamps...you normally clamp individual conductors) and measure AC amperage. If more than fractions of an amp show up, that juice is getting off the boat somewhere else. A few amps is enough to be sending a deadly current out in fresh water. If you randomly clamp cords in an average marina, the findings will be shocking (sorry). An ELCI is doing exactly what you're doing with your amp clamp, but it has circuitry that then cuts the juice.

#70 kent_island_sailor

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Posted 17 July 2012 - 07:29 PM

A flat out short of hot to ground *should* blow the breaker. Small amounts of leakage current have two choices to get off the boat - one is through water to ground and the other is through nice copper wire to a nice copper ground rod. You do NOT want to remove option 2 and send it all the first way!


I kind of understand how connecting and AC ground to battery might make it safer for the people on the boat in a failure mode BUT do not see how that makes it safer for people in the water ?

Assuming vessel's metal bits that are in the water (prop shaft, metallic through-hulls, etc.) are all bonded together and the vessel's DC "return" (nearly always battery negative in this day-and-age) is connected to that: Should shorepower AC "hot" become connected to the DC return, the water will be energized. If the shorepower AC earth/safety ground is bonded to the boat's "ground" system, and the AC hot becomes connected to it, the shorepower breaker should trip. That of course assumes the shorepower ground is actually connected to ground.

Jim



#71 DA-WOODY

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Posted 17 July 2012 - 07:44 PM

Hi, I wrote the original post, but just discovered this thread and joined Sailing Anarchy.

Kent_Island_Sailor is right, most of the time with Electric Shock Drowning it's muscle paralysis that disables the victim, and they drown. I screwed up, and this definition (the muscle paralysis one) is the common definition of ESD. We went over so many cases where the voltage differential was so pronounced that it just stopped the victim's heart, that I thought this was what always happened.

I agree that this stuff is expensive, but we marine electricians aren't getting rich installing galvanic isolators and ELCIs! Call it $450 in materials for a basic 30 Amp ELCI and galvanic isolator. It's very quick install on both of these, 1-2 hours, so not much billable time, and nobody every makes money off a job that's only 1-2 hours. And it's an Internet buying world now, so nobody makes much markup and parts either. Installing ELCIs is more of a public service.

My boat doesn't have either an ELCI or galvanic isolator, but it hasn't been plugged into shore power for about 12 years. The only AC I have is a portable inverter, and there's a reasonable argument for not having AC on a boat at all, but that's probably not for those of you who live where you'd suffocate without air conditioning.

Excuse me if this has been addressed before, but the done thing to check for leaks is clamping your shore power cord. You put an amp clamp around the whole cord (this is not how we're taught to use amp clamps...you normally clamp individual conductors) and measure AC amperage. If more than fractions of an amp show up, that juice is getting off the boat somewhere else. A few amps is enough to be sending a deadly current out in fresh water. If you randomly clamp cords in an average marina, the findings will be shocking (sorry). An ELCI is doing exactly what you're doing with your amp clamp, but it has circuitry that then cuts the juice.


Welcome to SA - FO&SUYWOGFT's

Hope you feel I gave proper credit to you for your helpfull imput

this post might fit better in CA BUT the message needs to go out to the masses and for that only SA will do

You have come to quite the sorce for help with all things Sailing now including the proper way to Sail without Shorts Posted Image

Warning do Not venture into AC-A or PA Jus Sayin Posted Image

#72 Great Red Shark

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Posted 17 July 2012 - 08:22 PM

Electrical Engineers are gods.

I love Tesla. I read a biography, what a Genius. We are still using his principals today. Kind of tells you how far the human race has come in the last 120 years (not far).


" Because you just can't spell GEEK without an EE. "

Tesla was perhaps one of the greatest innovators ever. Edison (who most folks think was pretty bright) was convinced we'd run the world on DC !

My take on the matter ? (in the words of Michael Keaton from 'Mr. Mom' to martin Mull)
" 220, 221 - whatever it takes..."

But stray currents can and DO kill, and Marine wiring is often a scary matter.
Have a good buddy that is a marine electrician whe regularly entertains us with (literal) hair-raising tales.

Recent accout: big new production cat isn't charging as it should, JG is down in the engine room tracing the wiring to find the issue and as some point puts his hand on a wiring bundle and feels real HEAT coming off the conductors throught the insulation. Ah ha.

Calls the owner over, "Feel this ?"
"Yeah" says the guy
"That's Bad...."

Your wiring harness shouldn't act like a heat trace - you risk letting the magic smoke out.

#73 MattZ

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Posted 17 July 2012 - 10:46 PM

Yikes. This thread is freaking me out, and I'm real glad I read it. Let me add my thanks to Da-Woody for the PSA and to clarkbeek for your work in this area.

'Leakage' from a boat and AC/DC grounding, etc aside and to simplify this as much as possible, I assume that a live 120v wire in (fresh) water will create a lethal voltage field for some distance around it, up to 60 ft. Is that correct?

The reason I ask is that I'm not concerned with boats, but with old docks and their aging wiring. I have 4 docks within 60 ft of my dock. One is relatively new, 3 should be condemned.

While the ELCI and galvanic isolators sound like a good idea, their installation won't be much consolation if I (or a family member) get electrocuted by someone else's nearby faulty wiring. There's definitely a business opportunity here, I need the ESD version of a smoke detector that'll sound an alarm if the conditions warrant it.

Maybe we should design one here as a group effort, like the FT10. We could save lives... That's pretty cool.

#74 Sailabout

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Posted 17 July 2012 - 11:59 PM

stay in salt water is way safer




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