Electric Shock Drowning and In-Water Electrocution

[Tomfoolery]

After the latest round of drownings due to electric shock in marina waters, especially those involving children, I started searching around for an authoritative explanation of the what and why, but was coming up dry. Coincidentally, just two days ago the ABYC released a presentation on Electric Shock Drowning, it's causes, a technical explanation of the physics involved, and how to prevent it. It's done in terms anyone can understand, so you don't need a physics or engineering degree to understand it.

The presenter is an ABYC Certification Instructor and Master Marine Technician who lost his son to electrocution while swimming in a marina. This presentation may only be available until August 19, according to the ABYC website, though I don't know why. This is something everyone with either a boat, a dock, a boat lift, or even who just hangs around a marina should watch. Incredibly informative, but very long at about 1-1/2 hours. I watched it in one sitting. So did my FIL, a powerboater of 50 years who can't sit still to watch a video for long, but couldn't pull himself away from this.

ABYC web site:

http://www.abycinc.org/

Direct link to the youtube video presentation "Hot Docks, Hot Boats, and Electric Shock Drowning":

http://www.youtube.com/watch?v=O7-s_mdE ... e=youtu.be

[mastreb]

Fresh water marinas should routinely check all new renters for current leakage when they sign in, and they should check their own floating docks annually.

[pokerrick1]

When I was living in San Felipe, Baja California, Mexico, they had just completed some new floating docks to lease, complete with electrity and water (more expensive than Marina Del Rey) - - and just before I got a slip it was learned that SOME of the slip electricity had been set up waaaaaaaaaay over the correct voltage and amperage (what a surprise - Mexican GOVERNMENT contractors) and that two boats had their entire electrical systems blown apart when they hooked up to the shorepower (I have no idea what would have happened to people if they jumped in the water to cool off???). Anyway, fortunately, it was repaired before I moved in and one of the other boaters checked everyones' shorepower for them after they were fixed.

Did the Mexican Government compensate anyone for the damages caused by their error? Ha Ha Ha Ha Ha Ha Ha!!! Funny!!!

Rick

[Boblee]

Not sure what the presentation showed but it takes very little voltage to kill and once the resistence of the skin is broken down especially in salt water very little amperage in fact a few millieamps if you are immersed in water, as then drowning is probably the actual cause of death.
Many people die in swimming pools from almost immeasurable stray voltage or even from placing a battery on the tongue on land let alone when immersed but certainly touching two low voltage (2-12v) probes with seperate hands while in saltwater would be dangerous.
Then Aussies per capita seem to find some strange ways to die.
http://www2b.abc.net.au/science/k2/stn/ ... 18991.shtm

[seahouse]

I guess maybe if they choked on the 9 volt battery(?)

[mastreb]

http://www.allaboutcircuits.com/vol_1/chpt_3/4.html

In a general sense, it's current that kills, not voltage, but there are resistance differences at the low and high end that modify that general rule a bit. 17 volts is the theoretically absolutely minimum deadly voltage under worst case condition (I.e., immersed is conductive liquid, and AC with sufficient current present). 28 volts is the lowest voltage known to have ever caused death and that was AC with a wet victim, 30 volts is the threshold considered dangerous, and above 50 volts is the voltage at which an electrical contractors license is required for installations.

I'm quite certain that these marina deaths are caused by shore power leakages. House 12 and 24 VDC systems can't kill a person by electrocution. They may startle and cause drowning, however.

[Boblee]

That could be correct Mastreb IF you are talking about purely electrocution being the cause of death but immersed in water especially salt water, drowning due to not being able to breath properly would be the cause of actual death the current flow prevents movement to access air or at least that is how I understood the explanation on swimming pool deaths, the same current on land would not be a problem and would need a much higher voltage to push it through the resistance barrier especially to cause actual electrocution.
ELCB's are normally 25 ma but have seen a fellow sparky (dry skin?) put one finger of each hand on terminals and then lick his fingers to check whether 240 or 415v but every situation is different, been booted many times, some a tingle and some like a steam train pushing through my chest, the difference being skin resistence (wet) or position and not being able to throw or fall off.
Also saw a TA lose his hand due to burns after the skin broke and I had trouble getting there quickly to pull him away that was 415 accross his hand and 240v through his body whenever he tried to push himself off the metal frame of the switchboard, didn't die but if underwater would have without doubt.