Grim reminder about electrical safety

[Bill D]

A couple swimmers were found in Lake Tuscaloosa last weekend after an apparent electrocution while swimming near their dock. This is a good time for everyone to check their electrical connections around the dock and remember the safety tips below.

• Check wiring often -- even a couple of times each year. Something as simple as a round of bad weather can cause damage.
• Make sure there's a ground fault breaker at the dock.
• Anyone who feels tingles or shocks while swimming, should move away from the dock, not toward it.
• Know where the power cutoff is and make sure others outside the water know, too.
• Plastic or wooden ladders are preferable, rather than metal or aluminum ones.

http://www.al.com/news/huntsville/index.ssf/2017/04/what_is_electric_shock_drownin.html

Edit: Authorities confirmed the COD was electric shock
http://www.al.com/news/birmingham/index.ssf/2017/04/2_lawyers_found_dead_in_lake_t.html

 

[tdonoughue]

Methinks this one deserves a sticky, [USERGROUP=3]@Administrative[/USERGROUP] ...

 

[PEARCE]

That's the very reason why our marina doesn't allow swimming around the docks. I realize this happened around the families private dock, but that is just awful.

 

[KXCam22]

Thats a good warning. I work with big electricity every day and it is invisible and likes to go everywhere. Cam.

 

[zipper]

Use GFCI breakers to feed circuits anywhere near water, a GFCI outlet only protects against faults downline from the outlet to an extent. It will not cut power from the feeder wire as the breaker will. If feeder wire becomes compromised and contacts the water it can kill.

 

[ripler]

I would never let anyone swim near a marina or a private dock that has shore power. I belong to a marina that has a water slide going into the river and I can't believe they allow this and I cringe every time I see kids using the slide. In my opinion every marina should not allow swimming around their docks. Even if the marina owner can guarantee that his dock wiring is safe you can't guarantee that every boat docked at the marina is safely wired. How many boat owners do you think hire a qualified marine electrician to wire their boat safely, or how many marinas hire a qualified marine electrician? Probably not many. How many do it yourselfers know that wiring in their boat is not the same as wiring in your house? The biggest issue is that most states do not require annual electrical safety inspections for marinas, this is a huge issue since there are a lot of marinas that disassemble their docks for the winter and reassemble in the summer without inspections. How many boat owners actually have their boats inspected to insure their wiring is not faulty and leaking current into the water? The issue of electrical shock around marinas has caused the National Electrical Code to react by making changes in the code for 2017, but most states don't require the use of the most recent NEC.

Here's a good explanation from Boat Us.

http://www.boatus.com/seaworthy/assets/pdf/marina-dock-safety.pdf

 

[haknslash]

I read the original story about their drowning when it happened and there was rumor of it on AL.com about it being from possible electrocution in the water. So sad for their families.

This will make me be more aware of swimming around docks.

 

[captainhook]

I'm trying to understand how this happened. Was the dock where the ladder was leaning metal too? I've always thought that electrical lines falling into a large body of water would trip a circuit breaker.

 

[Bill D]

Circuit breakers are designed for short circuit protection; where resistance goes to near zero and current instantly spikes. For a circuit breaker to trip, there needs to be an over-current in excess of 125% the rating of the breaker. In cases where there is enough of a load (resistance of the water x the distance) a circuit can form through the water and hold a steady current below the threshold to trip the breaker.

This situation requires the use of a Ground Fault Circuit Interrupter breaker. The breaker monitors the current on both the line and the load side of the circuit. Any small imbalance opens the breaker, removing the ground fault. A normal breaker doesn't pay attention to the load, just the supply.

 

[Speedling]

Circuit breakers are designed for short circuit protection; where resistance goes to near zero and current instantly spikes. For a circuit breaker to trip, there needs to be an over-current in excess of 125% the rating of the breaker. In cases where there is enough of a load (resistance of the water x the distance) a circuit can form through the water and hold a steady current below the threshold to trip the breaker.

This situation requires the use of a Ground Fault Circuit Interrupter breaker. The breaker monitors the current on both the line and the load side of the circuit. Any small imbalance opens the breaker, removing the ground fault. A normal breaker doesn't pay attention to the load, just the supply.

Excellent explanation! I don't have a dock or anything buti know what to look for now as we do rent slips from time to time.
I also look for this stuff with my camper since it is all outside connections. A gfci connection is small cost to what could happen

 

[haknslash]

I'm trying to understand how this happened. Was the dock where the ladder was leaning metal too? I've always thought that electrical lines falling into a large body of water would trip a circuit breaker.

They still don't know exactly the direct cause I believe. However a similar incident of another girl happened like this from the story so I'm guessing it wasn't the right type of circuit breaker:

The current that shocked Carmen Johnson was caused by water seeping into a light switch box at the family's dock, according to her mother. When the metal ladder was put in the water, the electrical current from the switch traveled through the dock, down the ladder and into the water.

"I think when Reagan touched the ladder and Carmen grabbed Reagan's legs trying to pull herself up, she got the full force of the current," Casey Johnson said.

 

[ripler]

Use GFCI breakers to feed circuits anywhere near water, a GFCI outlet only protects against faults downline from the outlet to an extent. It will not cut power from the feeder wire as the breaker will. If feeder wire becomes compromised and contacts the water it can kill.

The issue with this is that marinas are not required by the national electrical code (NEC) to install GFCI outlets, they are only required to install a ground fault protection (GFP) device which is for equipment protection and not personal protection like a GFCI. The old NEC allowed a trip current on the GFP to be a maximum of 100mA, the new code reduces this maximum to 30mA. Just for reference the GFCI in your house only allows about 5mA of current before it trips. The new NEC also requires marinas to install a warning sign that says "WARNING POTENTIAL SHOCK HAZARD-ELECTRICAL CURRENTS MAY BE PRESENT IN THE WATER", this is just a CYA.

To protect you, your family and friends do not let them swim within 100 yards of a marina or private dock.

 

[Bill D]

I read in another article that an investigator was shocked and they found electricity running through at least part of the pier. Such a shame. My wife said that they were at a family friends place.

 

[MattFX4]

Sad story. I have witnessed this same thing first hand at a lake also in Alabama. Was out with some friends wakeboarding and the guy we were towing let go near his dock. He instantly starting seizing up and was locked up due to the electricity. Us on the boat thought he was having a seizure so two guys jumped in to help him. Well right away the guys who jumped in started screaming and one sank to bottom of lake because he wasn't wearing a vest. This saved his life because he must of got away from the current. The other guy who jumped in was wearing a vest and was electrocuted. My friends granddad was on the shore and cut the power. We dragged him up on the dock, and performed CPR until the first responders arrived. Sadly he didn't make it and died on way to the hospital. Guys, this is no joke. One of the most tramatic things I have ever seen. I will never forget the look in my friends eyes when he was in the water being electrocuted. I thank god everyday I did not jump in the water that day and staid on the boat.

 

[Bill D]

That's terrible @MattFX4! Sorry you had to be a part of that.

 

[bronze_10]

Not just marinas... we had a teen age girl here who was working as a life gaurd. She grabbed the metal ladder to lean over to check the water ph level and was shocked. She fell in and died from it. A storm messed somethong up in the pump room that was not wired correctly.

 

[zipper]

The issue with this is that marinas are not required by the national electrical code (NEC) to install GFCI outlets, they are only required to install a ground fault protection (GFP) device which is for equipment protection and not personal protection like a GFCI. The old NEC allowed a trip current on the GFP to be a maximum of 100mA, the new code reduces this maximum to 30mA. Just for reference the GFCI in your house only allows about 5mA of current before it trips. The new NEC also requires marinas to install a warning sign that says "WARNING POTENTIAL SHOCK HAZARD-ELECTRICAL CURRENTS MAY BE PRESENT IN THE WATER", this is just a CYA.

To protect you, your family and friends do not let them swim within 100 yards of a marina or private dock.

I agree, but what I am trying to say is that GFCI outlets are not adequate protection at any dock. The line side is not protected, but using a GFCI breaker to feed the circuit will provide protection back to the panel.

 

[ripler]

I agree, but what I am trying to say is that GFCI outlets are not adequate protection at any dock. The line side is not protected, but using a GFCI breaker to feed the circuit will provide protection back to the panel.

I agree, didn't pay close enough attention to your last sentence. Sorry.

 

[Jgorm]

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?

 

[tdonoughue]

Unfortunately, very easily. In fresh water, electricity travels through the body (which is primarily salt water) more easily than it does through the fresh water. So, basically, the human body is a nice 'short cut' for the electricity wherever it is traveling in the fresh water. So if there is current flowing through the water and you get near it, it takes the short cut through you.

As to how the electricity gets into the water: that is why this is such a difficult issue and the advice is to not go in the water near docks. Yes, it may be a metal dock. But it may equally be a metal ladder on the dock that is shorted out through some trim metal, or a boat docked there that is leaking electricity through the prop/impeller. Or basically anything else that is metallic and touching the water. Could be caused by a corroded connection somewhere, or one that fell off or a rodent eating something... And if the electrical system is not designed to 'stop' when there is such leakage (like with the GFCI's back at the source as discussed above), then someone can get zapped. Without warning.

I am just about as big a do-it-yourselfer as they come. Built houses and the whole bit. But this is one area where if you have a dock with power, you had best have a real licensed electrician checking it out annually to make sure everything is good. Too much danger if it is done wrong. Not something with which to toy.