Grim reminder about electrical safety

[zipper]

We're these all on metal docks? I can't see a wood, concrete, or fiberglass deck causing this issue. I grew up on a salt water dock with shore power every 20'. This is the first I've ever heard of something like this. How is someone swimming going to be shocked if they are already grounded and not touching anything?

@Bill D above in post #9 explains it well. No metal dock or ladder needed, all it takes is a break in insulation or improper wire and contact with the water or metal pole supporting a wooden dock. Use a GFCI breaker.

 

[Noko]

I have shore power to the boat. I am always careful but I was going to upgrade how the power gets to the boat. Definitely going with a GFCI plug.

 

[Jgorm]

@Bill D above in post #9 explains it well. No metal dock or ladder needed, all it takes is a break in insulation or improper wire and contact with the water or metal pole supporting a wooden dock. Use a GFCI breaker.

No. You can't get shocked unless you connect hot to ground. If you stand on a plastic chair you can hold hot wires. If your in the water, ours the same as being grounded. If you put a hot wire into the water it will not electrocute everything in the water. If you are standing on the ground, in the water, near the hot wire you might get shocked. I had a short in my salt water reef tank. It would shock me every time I touched the water, unless I stood on a chair. My fish were unaffected.

 

[zipper]

Depends on the amount of current leaking and your proximity to it, and I am sure the folks who died from electrocution around docks and other scenarios wished they had your chair at the time. The point is to use GFCI protection around all wet areas. Had your tank had one it would have tripped instead of shocking you.

 

[zipper]

http://www.boatus.com/seaworthy/magazine/2013/july/electric-shock-drowning-explained.asp

 

[Bill D]

For electric current to flow, there are 2 things that are required; A potential difference, and a path for current to flow. In @Jgorm's example, the chair removed the path to ground. But if you are standing on the chair and touch another conductive item that is connected to ground, there is a path again. The human body has resistance to electric current flow (something like 2 mega-ohms) so there does need to be enough voltage to "push" through that resistance. In any situation where your body becomes the path for current to flow from one potential to another, you will be shocked.

A person in the water is not grounded, they are at the same potential voltage as the water. This is the same thing that happens when you touch the hot wire on the insulated chair or ladder. Therefore, there is no potential difference to push the electric current. The problem arises when they create a path by touching something at a different potential. That could be something grounded (0 volts) or something that is farther from the source of the voltage (1/2 or 1/3 of source voltage. The latter is commonly referred to as step potential. (http://stepandtouch.com/whatis/)

End of the day, electricity is a sneaky guy. A GFCI protected circuit is the best way to guarantee safety around your dock. And it doesn't cost but a few extra dollars.

 

[ripler]

@Jgorm Heres a paragraph from and engineering website explaining why you don't need to be touching anything and still get shocked.

Regardless of the size of the AC fault, the potential may rise to lethal levels as low as 15VAC. Even with a poor ground, a boat in salt water won't develop enough potential to cause a problem for a swimmer, making this an unheard of phenomenon with boats in the ocean. However, lakes are a different story. Fresh water is a very poor conductor by comparison, so an ungrounded fault will raise the potential on the hull as it attempts to enter the water. A swimmer represents a much lower resistance fault path, even if only in the electric field and not touching anything.

 

[Jgorm]

I did have a gfci on my tank, but it was obviously broken. Lots of gfcis are broken. I think they need to be tested monthly. I'm not trying to disagree, just understand how it happens. I spend a ton of time around water and would never want this to happen to anyone. I still think that the depth of the water, or the proximity to a conductive ground had to play a key role in these fresh water electricians. The swimmer would have to be part of the path conducting hot to ground. I can't see it happening in deep water near floating non conductive docks. I can easily interested in shallow water around metal docks. I've been shocked 1000 times and don't even bother to shut off breakers when replacing switches and outlets. I'd bet that if you feel a shock while in the water, you could back float and swim away from anything near by. It never hurts to have a potential exit plan!

 

[Noko]

I was surprised that if there was enough voltage to kill someone, why didn't the breaker trip? Who knows what strange things people do. Theres a meme here showing a circuit breaker being wired closed. So who knows.

 

[flyingnugget]

Good LORD! This is a horrible story...

I'm scared out of my mind now... Just rented a lake house on Lake Martin in AL for a week and I'm having second thoughts about my kids swimming at the dock..
Damn it all...

 

[Bill D]

I wouldn't fret about it @flyingnugget. Think about how many docks there are out here and how few stories you hear like this. If you wanted to be extra careful, you can check if the rental dock has shore power and just isolate it at the breaker panel during your stay.

 

[007]

The grim truth is that these types of accidents are usually just that, an accident. Sometimes its a wire frayed from rubbing up and down with a bobbing boat/lift, sometimes its wire insulation that just cracks overtime on an extension cord run from one place to another long ago. Sometimes its the neighbors dock that kills, not yours. We had the lake flood a year and a half ago and a few people lost their freaking minds because the condo complex cut the power to docks where the electric was submerged at the shore connection. That same summer on a different part of the lake a couple people were electrocuted similar to the stories on this thread. People don't think about electric and water! Heck, I grew up swimming around docks, but now I look down the row and see at least one poorly maintained boat running a splitter off of a pig tail that I am not sure is GFCI protected. I remember stories like these and I decide its more fun to go swimming off the boat in the middle of the lake.

 

[KXCam22]

Nomo. It takes 15A to trip a breaker but only 10mA to stop your heart. In most cases the water presents enough resistance that the 15A current level is never reached. Cam.