Marina Dock Safety and Electric Shock Drowning

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Instructor Bio - Chris Dolan Senior Applications Engineer 13 years of experience with Eaton - Marina Power and

Lighting Oversees more than 600 electrical designs a year Experienced in power pedestals and distribution, and

electrical safety and efficiency Speaker at numerous industry events Contributor to the upcoming ASCE manual for marina

design

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Instructor Bio Ed Sherman Director, Educational Programming, American Boat &

Yacht Council (ABYC) Award winning author of multiple best selling marine

books. Titles include: Outboard Engines, Power Boaters Guide to

Electrical Systems, 12 Volt Bible for Boats 2nd Edition, Advanced Marine Electrics and Electronic Troubleshooting, Co-Author, Fundamentals of Marine Service Technology

Frequent IBEX speaker. Contributor to Cruising World, Boating, Professional Boat

Builder magazines. Owner, www.EDSBoattips.com

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Electric Shock Drowning and the Causes

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What is Electric Shock Drowning?

Electric Shock Drowning occurs when faulty wiring on a boat or in a marina causes underwater metals to become energized.

Examples of underwater metals that could become energized:

Boat Props Dock Frames

This creates an electrical eld in the water. The magnitude and intensity of the electrical eld is determined

by how much current is being leaked into the water.

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A swimmer enters the electrical eld and completes the electrical circuit to ground.

The swimmer becomes a target for the electrical current leakage because the human body is a beFer conductor of electricity than fresh water

Fresh water is close to 70 times more resistive than salt water. This makes electric current leakage in fresh water marinas a major concern.

Depending on the amount of current in the water and a swimmers location relative to the electrical eld, a person may experience eects ranging from a slight tingle, to complete loss of muscle control, to ventricular brillation.

What is Electric Shock Drowning?

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50mA of Leakage

20mA of Leakage

5mA of Leakage

Underwater Electrical Field

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Current not Voltage Light Bulb

100 mA

Current Effects 1 mA to 8 mA Tingle, sensation of shock, not

painful, muscle control not lost

8 mA to 15 mA Painful shock, muscle control not lost

15 mA to 20 mA Pain shock, muscle control is lost, paralysis / inability to swim occurs, labored breathing

50 mA to 100 mA Ventricular Fibrillation possible

100 mA to 200 mA Ventricular Fibrillation occurs

200+ mA Burn marks may appear, chest muscles clamp heart

Electric Shock Drowning Medical Facts

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Line 1 (Black) current carrying conductor

Line 2 (Red) current carrying conductor

Neutral (White) returns current to complete circuit

Ground (Green) oers current another path to complete circuit if short or overload occurs

Basics of the Electrical System

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Basics of the Electrical System

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Example: 30 amps out on line to the receptacle

29.5 amps returned via the neutral

Grounding conductor picks up the remaining 0.5 amps before it can leak

into the water

Properly Functioning Electrical Circuit

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Example: 30 amps out on line to the receptacle

29.0 amps returned via the neutral

Faulty ground only picks up 0.5 amps

0.5 amps are leaked into water, presenting a potential problem.

Inadequate Electrical Circuit

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Two things are required for Electric Shock Drowning:

1. An electrical fault to ground either in the marina or on a boat

2. An incomplete circuit caused by a faulty or nonexistent circuit back to the docks grounding system.

Brief Review Two Keys to Remeber

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NEC 555.3 Ground-Fault Protection

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New to the 2011 National Electrical Code The main overcurrent protective device that feeds the marina

shall have ground fault protection not exceeding 100mA. Ground-protection of each individual circuit breaker or feeder circuit shall be permiFed as a suitable alternative.

Overcurrent protection device the device that disrupts power to a circuit or piece of electrical equipment in the event of an electrical problem. Examples include circuit breakers and fuses. Circuit breakers are the most common form of ground-fault protection devices.

There is a similar code that applies to oating buildings also requiring no less than 100mA protection for oating buildings NEC 553.4.

NEC 555.3 Ground-Fault Protection

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Where can 100mA Ground-Fault Protection be Located?

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Circuit breaker protection can be located where the incoming power enters the facility from the utility company.

While an economical solution, it may be dicult to pinpoint the exact cause or causes of the current leakage.

Protection at the Utility Entrance

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Circuit breaker protection can be located at the head of each dock within a disconnect or distribution panel.

Comparatively, this is also an economical solution.

Identifying the cause or causes of the leakage depends on how the system is wired.

Protection at the Head of Each Dock

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Circuit breaker protection can be located on each dock within a distribution panel or through a ground fault monitoring system with shunt trip circuit breakers.

While this is a more costly solution, it is relatively easy to identify the cause or causes of the leakage.

Protection on Each Dock

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Circuit breaker protection can be located in each power pedestal through ground-fault circuit breakers.

This is a very costly solution, but is very easy to identify the cause of current leakage. If the circuit breaker trips, the boat or piece of equipment plugged in is experiencing a problem.

Protection in Each Power Pedestal

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What Can Be Done to Lessen the Chances of an Electrical

Show Drowning?

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Do not allow swimming in your marina. Post signs prohibiting swimming in the marina.

General Rules No Swimming in the Marina

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Set aside a window of time where people can work on boats in the water when the electricity will be turned o.

Post dates and / or times. Inform customers and workers no power will be available on the

docks.

Customers need to be aware their power will be turned o during these working windows.

Contractors will need to be aware that no electricity will be available for power tools.

General Rules Designated In-Water Work Times

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Electrical work should only be completed by certied electricians.

Marina work should comply with all NEC and NFPA codes. Routine maintenance and inspections should be performed at least annually per NFPA 5.20 Maintenance of Electrical Wiring and Equipment.

Document inspections and maintenance for liability purposes.

Boat owners should have all electrical work completed by ABYC certied electricians.

Boat owners should also document inspections and maintenance for liability purposes.

General Rules Electrical Work

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Ground Fault Monitors

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If possible turn o all power sources that may come in contact with the water. Area should be deemed safe before any action is taken.

Extreme caution should be taken when removing victim from the water.

Call 911 immediately Begin articial ventilation - victim with pulse, but not breathing

OR

CPR - victim without pulse and not breathing use (AED) Articial Electrical Debrillator if available

First Aid for Electric Shock Victims

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Signs of Electric Shock Drowning or Potential for

Electrical Shock Drowning

Often leaves no bodily clues to suggest anything but simple drowning due to alcohol intoxication or heart aFack.

No signs of burning due to the victim being submerged in water no signs of electrocution.

Often classied as electrical shock due to evidence of great distress, multiple deaths

Signs of a Potential Problem: Tingling sensation reported by anyone swimming in the marina.

Excessive damage to metal boat parts in the water props, etc

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NFPA 303-5.20 Maintenance of Electrical Wiring and Equipment

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NFPA 303-5.20 Maintenance of Electrical Wiring and Equipment

An inspection of all electrical wiring, ground connections, conduit, hangers, supports, connections, outlets, appliances, devices, and portable

cables installed or used in a marina, boatyard, boat basin, or similar establishment shall be made at regular intervals to ensure a complete inspection at least annually.

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NFPA 303-5.20 Maintenance of Electrical Wiring and Equipment (cont.)

The inspection required in 5.20.1 shall include a test of the ground integrity and polarity.

The use of grounding-type portable electrical equipment that is not properly and adequately grounded shall be identied and removed from use or repaired.

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Lets look at several super tools

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And a couple of not so super tools.

A custom built meter probe:

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A regular DVOM:

The very rst step in this process is to determine the integrity of the wiring at

the dock box.

Bad wiring at the dock pedestal may induce errors to all of your readingsso, lets

begin with the SureTest tool.

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What will the Sure Test tell us?

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We will be using this tool to determine some very important things about the dock wiring.

Ground, neutral and hot wire integrity

Voltage drop, available short circuit current

Actual resistance in ohms for each conductor

And more.

Initial look is similar to the common LED tester

In the example shown, the tool is indicating an open ground, a very dangerous situation that should be corrected before going any further.

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The tool has a decoder chart on its back face..

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The false ground feature is referring to a neutral to ground connection. This can be a bit tricky depending upon where you are conducting the test.i.e. on the boat or at the dock pedestal.

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Here, we are measuring line voltage

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Here, we are measuring peak AC voltage

Another voltage reading the Sure Test can provide is a

neutral to ground leakage voltage.

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Anything less than 2 volts is acceptable.

Excessive reading

here indicates neutral to ground current leakage.

Line voltage should read 120VAC +/- 10% at 60 Hz

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Here we are testing the frequency..60 Hz

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Here we are measuring voltage drop.this

is an indicator of inadequate wire gauge or

poor quality terminations

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Here we are also measuring voltage drop, but at a higher current

level..

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ASCC or available short-circuit current level. Need to multiply by

1000, so in this case we see only 80 amps available. Not very good and

again, indicative of a poor connection or wire too small

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Here we are measuring the actual trip current for a GFCI device..

Once we have established that the dock is OK, now we can

check for ground fault leakage from boats

Now we bring the inductive AC leakage amp clamp into the mix..

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When using the AC leakage amp clamp, process of elimination is really a

big part of what you are doing..

Simply, this means that what goes down the hot conductor must come back to the source via the neutral conductor.

This would give us a zero amp reading on the clamp meter.

Anything other than zero is a measurement of the differential, or leakage current.

This current will always fault to ground , which hopefully is a supplied conductor in excellent condition on the dock.

Unfortunately we now know that this is often not the case.

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AC is sometimes referred to as zero sum

Turn off the boats AC devices one at a time until the leakage measurement zeros out.

You will have then identified the source. If the measurement does not zero out then the

source of the leakage current is elsewhere on the dock or a problem at the source.

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To determine where the leakage is coming from..

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To determine where the leakage is going to..I use my dock wand

High amperage readings that keep getting higher as on board appliances are turned on usually indicates a neutral to ground connection at the panel.

This is actually quite common in spite of the ABYC

E-11 directive that states not to do this.

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Other reading possibilities or clues.

Remember that every boat connected to the dock wiring system is a contributor.

So, its best to test dock wiring integrity when all the boats are disconnected.

ABYC Techs should never, ever disconnect a boat from its dock pedestal without the boat owners consentnot even for a few minutes!

Start at the farthest away from the shore and work inward toward the dock source to try and isolate problems.

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In my experience it is best to test docks in the o season..

Thank You! Are there any additional questions?

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