what do ya think

[STOGEY]

The last time I went on a charted dive with the Day Breaker and Capt. Fran Marcoux. He was telling us how many divers end up getting cardiac arrest while doing a dive from a boat dock. Sometimes these boat docks have electrical outlets, and with these outlets sometimes there is a lot of stray high voltage that seeps into the water.

Sometimes this stray voltage may affect the rythym of peoples hearts and causing them to go into cardiac arrest.

Has anyone else here heard of this happening, and how often do you think that this occurs?

 

[Cacia]

wow

I have only heard about the electricty in the marina as it relates to electrolysis and boat maintenance.

Usually we don't dive in these areas for other reasons....traffic and murky water.

 

[diverrick]

If a single leg of a 110 volt circuit is in salt water, or both for that matter, I would have to guess that the circuit breaker would trip right away, as that would be a direct short to ground. Add to that, that GFI's have been required on all curcuits, even remotely near water, for many years, (at least in the USA) I find that story very hard to believe. Maybe it has occured, sometime in the past, but as the issue of electricity "straying" into the water... hog wash IMHO. Any one else have an opnion?

 

[1_T_Submariner]

Stray voltage in the water. Umm hard to believe. Not sure how regular outlet would give you that.

 

[JahJahwarrior]

Well, the wiring in a marina can often set you up to be the "zinc anode" for all of the other boats in the harbor.....some great photos of swiss-cheese engines from that effect, which is preventable with...want to say an isolation transformer?


As per stray electricity, I don't think that's plausible. If the person talking to you isn't an electrical engineer and they are talking more indepth than "stick a fork in an outlet and you get shocked," then take what they say with a grain of salt. Electricity and more specifically, electromagnetism (as the two are related) is very difficult to understand. There could be a magnetic field near wires, you can see this, Ithink, from the way a flourescent tube glows very very subtlely if you stand under high voltage power lines. (might be wrong, I'm not an electrical engineer!) But there shoudln't be "stray voltage." Capitalism prevents it. Stray voltage means electricity flowed, when electricity flows, someone pays. If the marina has a super high bill, they call and electrician and fix the problem. If the electric company is losing electricity somewhere, they fix it, otherwise, they are losing money!


Pics or shens!

 

[dbg40]

Sounds like pure crap to me. And an injury like that in the US that was found to be a common occourance would have a new code installed overnight to prevent it.

 

[Charlie99]

Sounds like pure crap to me. And an injury like that in the US that was found to be a common occourance would have a new code installed overnight to prevent it.

Having a code and having everyone one in the world build and maintain their systems to the code are two different things.

All it takes is a GFI that is defective, hasn't been installed properly, or was bypassed because it was defective (or kept tripping for good reason). Then that unprotected circuit feeds shore power to a boat with electrical problems ---- sometimes as simple as hot and neutral exchanged in the shore power cables, or more often the adaptors whipped up on the spot because cables and plugs are different. (Typically 20A, 30A, and 50A feeds have different cables and plugs and boaters get frustrated when they are setup for something different that what's on that marina's dock.)

Thankfully, these sorts of problems are most often detected by extremely rapid corrosion on boats.

Bad shore power feeds is one of the hazards of divers doing hull cleaning and other ship husbandry.

 

[turtle_guy]

From what i understand about electricity it always flows in a circut unles it its the static kind so i dont see how stray electricity is even possible unles the outlet was comepletly under water and still flowing

 

[Charlie99]

As per stray electricity, I don't think that's plausible. If the person talking to you isn't an electrical engineer and they are talking more indepth than "stick a fork in an outlet and you get shocked," then take what they say with a grain of salt. Electricity and more specifically, electromagnetism (as the two are related) is very difficult to understand. There could be a magnetic field near wires, you can see this, Ithink, from the way a flourescent tube glows very very subtlely if you stand under high voltage power lines. (might be wrong, I'm not an electrical engineer!) But there shoudln't be "stray voltage." Capitalism prevents it. Stray voltage means electricity flowed, when electricity flows, someone pays. If the marina has a super high bill, they call and electrician and fix the problem. If the electric company is losing electricity somewhere, they fix it, otherwise, they are losing money!

If you manage to get the hot side of a 110VAC line connected to a steel hulled fishing boat, current will flow from that ship to a ground. (Or more specifically, from hot to gound then to neutral, but the ground and neutral will be tied together at the main power panel). Often the nearest return path is other boats. Anywhere between the two you can get quite a shock.

You can feel tingles at less than 1mA (0.001A). On an arm to arm path, since it goes through the heart area, just 5mA can be enough to stop the heart or put it into fillibration. I doubt that a harbor would notice if a boat was shoving 1 full amp (1000mA) into the water since that about the same as a 100W bulb.

This sort of problem shouldn't be common, but it does happen. Usually due to improper wiring. Most boat owners do a lot of their own work and not many of the them are electricians.

http://uscgboating.org/recalls/pdfs/BSC81.pdf is a US Coast Guard Safety Circular that reviews shore power problems. It also mentions a case of a swimmer being electrocuted.

 

[Charlie99]

http://neccode.com/newsletters.php?action=reply&inResponseTo=26&letterID=36 has a list of 25+ electrocutions, and a bunch of near misses.

A lot more than I expected. This source has managed to compile a list of 2 or 3 electrocutions per year, mostly of swimmers, caused by shore power and boat wiring problems that energized the water around boats and docks.

(It was one of the top results of googling "swimmer shore power electrocution".)