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Electric Shocks at Boat Mariner

08/01/2008 5:16 PM

We have a new lake front mariner made up of plastic docks for 30 pontoon boats. The mariner also has lighting & 110V AC outlets to charge boat batteries. We are currently experiencing electric shocks when a boater walks out on the plastic dock & touches the boat's metal frame.

Q1: Is this due to the plastic docks or the 110V AC power lines which are enclosed in waterproof flexible electrical tubing & run along the docks (some under the dock to the next dock)?

Q2: How do we investigate & trouble shoot this problem.

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#1

Re: Electric Shocks at Boat Mariner

08/01/2008 6:48 PM

Check this site for a number of discussions on Boat Marnia Shocking.

http://forums.mikeholt.com/search.php?searchid=954265

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#2

Re: Electric Shocks at Boat Mariner

08/03/2008 7:01 AM

Get a decent MARINE electrician that knows what he is doing.

Unfortunately there are many electricians.......automotive and general electricians that are very competent in their fields..........BUT...............do not know much about marine electrical systems.

I have several stories that could..............literally...........make your hair curl.

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#3

Re: Electric Shocks at Boat Mariner

08/03/2008 7:15 AM

Hi, I was also facing same type problem but what I have done All the Equipments are earthed through a flexible cable which goes inside the 3m deep water of sea and at the end of cable we hanged a 1.2 m long 38 mm dia GI pipe, now this arrangement working like a earth pit and no leakages on the working plateform

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#4
In reply to #3

Re: Electric Shocks at Boat Mariner

08/03/2008 10:17 AM

One does need to be careful.............doing things like this, with no expert opinion, can cause stray electrical current corrosion on vessels using the marina.........particularly aluminium hull vessels.

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#5

Re: Electric Shocks at Boat Mariner

08/03/2008 11:08 AM

Do you have any disconnects in the line where you can cut off power off to sections and maybe isolate the problem down to a certain section of the dock then repair from that point?

Every dock I have had my boat at always had disconnects incase someone damaged the dock they could react to it. I have seen large steel hull boats come in too fast and take out a couple of sections before they got stopped.

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#6

Re: Electric Shocks at Boat Mariner

08/03/2008 2:41 PM

Hi Sully,

A1: I would suspect that you are experiencing static electricity from the plastic. The plastic should be an insulator for the power outlets. Power outlets normally have the conduit grounded. Is the conduit metal or plastic?

A2: Rubber soles on shoes probably makes the static situation worse. Try using leather shoes to see if it gets better. Try to walk without sliding your feet, or stand awhile before touching the boat to dissipate the static.

Regards,

S

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#7

Re: Electric Shocks at Boat Mariner

08/04/2008 1:20 AM

American Boat and Yacht Council (ABYC) recommended practices require that the AC shore tie cord's green bonding wire be joined on a boat to the DC negative bus and the underwater gear bonding system. Should a fault develop on the boat, the fault current in the ground wire will initiate a breaker trip or at least prevent a potential (voltage) rise on the hull or underwater gear*. However, there's no way to know if the ground (green) wire is OK under normal operating conditions.

A possible clue to this problem is zincs that disappear rapidly for no apparent reason, however this doesn't always happen as an indicator.

Current takes all paths back to the source, so even with a good "green wire" ground system there still may be a small voltage rise on the hull as a fault establishes a parallel current path in the water. The boat may become lethal, however, if the ground return is damaged and located in fresh water.

* Outdrives, metal through-hull fittings, grounding plates, etc.

THIS IS A SERIOUS PROBLEM THAT CAN RESULT IN DEATH BY ELECTROCUTION, either in the water or on the boat! FIX IT IMMEDIATELY!!! I've been a responder in cases like yours and hated each fatal one for the needless deaths.

Ralph, the old Coastie

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#8
In reply to #7

Re: Electric Shocks at Boat Mariner

08/04/2008 8:16 AM

Standardsguy has an interesting theory but ERENGINEERING is spot on with his concern about electrocution. You need to get this system checked out immediatly before somebody gets killed. It's that serious.

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#12
In reply to #7

Re: Electric Shocks at Boat Mariner

08/04/2008 10:25 AM

If people are getting shocked when touching the metal on the plastic boats, that metal would have to have continuity to the shaft.

I wonder if these boats even have any sort of bonding system - IE zincs.

If this is a fresh water lake (which I suspect given plastic pontoon boats), stray current is even more deadly in a fresh water marina than in a salt water or brackish marina. The reason being that a person in fresh water is a better conductor than the water because of their salt content. In sea water the water is as good of or better conductor so the current pretty much bypasses the body.

I would not let any swimmers in the water until the boats are bonded and the shore power is installed correctly. If there is this much stay current I would imagine they are seeing a lot of corrosion of the props and shafts, not to mention other boats near by.

Which raises another question, are there any other boats in the water in the same marina? If another boat is connected to shore power and that boat has a poor bonding system that boat could be the source of the stray currents.

Many marinas are known to be "hot". The marina at Newport Beach, CA is notoriously hot. One of the yachts we built was moored there for a week and all of the zincs were nearly gone by the time they left, so a diver had to go in and install new zincs.

Travis

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#16
In reply to #12

Re: Electric Shocks at Boat Mariner

08/04/2008 3:01 PM

Guest Travis and I are on the same page. Anybody who's worked on the water at a marina knows this problem. If any of your marina boat owners use divers to clean the bottoms and restore zincs, warn them not to send a diver down. You could find him floating a few feet down and get nailed yourself when you tried to retrieve the body. (I've had memory chills ever since I read the original post. I was a Coast Guard officer and saw a few of these incidents turn out really bad.)

Ralph

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#9

Re: Electric Shocks at Boat Mariner

08/04/2008 8:38 AM

You need to have a serious examination of the boats wiring systems which are moored to your pontoons, most faults arise from voltage leaks to ground from faulty connection boxes and or incorrect wiring.

I suggest you disconnect all boats in turn until your fault disappears, then reconnect and disconnect in turn just to make sure you do not have more than one causing the problem.

As said earlier serious corrosion problems can arise from leakage currents.

Garth CR4

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#10

Re: Electric Shocks at Boat Mariner

08/04/2008 9:23 AM

As stated, this is serious. Disconnect all boats immediately. Test for voltage between a known good ground, and each section of the dock as well as any metal parts of the dock, and of coarse the ground point in the receptacles the boats would plug into.

If there is voltage, there is a serious error in the wiring of the dock.

If there is no voltage, disconnect the wiring for the dock, and test for resistance between the neutral wire and the ground wire. If the dock is disconnected from the shore power, there should be no connection between these two wires. If so, there is also a serious wiring error in the dock.

If all of the above check out well, there is probably a problem on one of the boats that is plugged into the shore power. Again test for voltage between a known good ground, and the ground point in one of the receptacles designed for the boats. One at a time have the boats connect. I think you will find one of the boats is causing the problem.

If you lack the equipment for this, or are not comfortable doing this, HIRE someone who is qualified and has the equipment. Be very careful. This is not a place to rely on luck.

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#11

Re: Electric Shocks at Boat Mariner

08/04/2008 10:19 AM

Hi.

I concur wholeheartedly with Mobi and ERENGINEERING.

It would seem that the earth from your local transformer is not connected along the dock and that one of the boats has an earth fault. Get a marine electrician to look at the problem. You have a potentially lethal situation. Your standards are different in the USA compared to Europe but if the installations are to ABYC then this cannot happen.

Chas

ElectroMarine Balear

Hi.

I concur wholeheartedly with Mobi and ERENGINEERING.

It would seem that the earth from your local transformer is not connected along the dock and that one of the boats has an earth fault. Get a marine electrician to look at the problem. You have a potentially lethal situation. Your standards are different in the USA compared to Europe but if the installations are to ABYC then this cannot happen.

Chas

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#13

Re: Electric Shocks at Boat Mariner

08/04/2008 12:14 PM

It does not take many volts to give you a shock. Even a 12-volt battery will bite when you are wet with salt water.

You need a good electrician to chase this to the actual fault. Before someone with a pacemaker falls dead on you.

Faulty grounds, unbonded neutrals, and an outlet wired with neutral to hot and hot to neutral will give you voltage leaks.

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#14

Re: Electric Shocks at Boat Mariner

08/04/2008 12:48 PM

Two theories about the source of your problem have been presented but the question you asked was about diagnosing so, Get a voltage meter and check the voltage that is producing the shocks. If you connect the meter to the boat and read a high voltage that dissipates rapidly through the bridge circuit in the meter your probably looking at static build up from the plastic docks. PVC is a very good triboelectric material (Builds a static charge when rubbed)

If static discharge is the cause the concerns about electrocution are lessened but concerns about comfort and explosion hazard remain, so using slightly conductive mooring lines, ground connections for each boat or a slow discharge material on the boat railings are possible remedies to explore.

If the meter reads a voltage that is some more steady fraction of 110V then you are probably looking at a current leakage situation and this should be addressed by the best electrician you can find for the job.

I would not feel comfortable giving advice on addressing these issues although other commentators have made some good points.

Mr. Gee

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#15

Re: Electric Shocks at Boat Mariner

08/04/2008 1:19 PM

It sounds like you have a safey issue with possible lethal consequence if you do not address this ASAP.

It also sounds like your dock side power system is not properly grounded. (or rather the boats are grounded but the docks are not and

Highly recommend you contact a qualified/licensed electrician to test/trouble shoot the grounding of your system ASAP. (I.E. NOW) He should also be able to tell you how to correct the problem.

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#17
In reply to #15

Re: Electric Shocks at Boat Mariner

08/04/2008 3:55 PM

Judging by comments from gentlemen more experienced than myself, I need to modify my earlier reply:

Revise "qualified/licensed electrician" to read

"Qualified Marine Electrician"

Question: Is there a separate license or certification for Marine Electricians?

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#18
In reply to #17

Re: Electric Shocks at Boat Mariner

08/04/2008 4:57 PM

The INSTITUTE OF MARINE ELECTRICAL ENGINEERS awards 2 relevant classes of recreational boat marine electrician competence categories.

Class 2A is qualified in both AC and DC small boat power systems (AND marina systems.)

Class 3A is qualified in small boat DC systems only. Ergo, not marina systems.

Unfortunately, not many small boat marine practitioners belong to the IMEE so it's hard to tell who's been blessed with the marine electrician's holy water sprinkled by the IMEE.

Ralph

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#19

Re: Electric Shocks at Boat Mariner

08/05/2008 12:41 AM

Hi Sully, I also agree with StandardsGuy. The moment I read your problem I also thought of the same solution. Plastic boats accumulate static charge, needless to say high voltage, due to rubbing action as mention by StandardsGuy. At our office we experience this everyday because of synthetic cloth cover of chairs and synthetic soles of shoes. One solution I told people is to touch the body of the PC once in a while and before touching any colleague who should not jump because of the discharge of your static accumulation through his/her body.

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#20

Re: Electric Shocks at Boat Mariner

08/05/2008 6:47 AM

it's hard to tell who's been blessed with the marine electrician's holy water sprinkled by the IMEE.

Hi Ralph, let's not get too facetious about this (hahaha).................as I pointed out earlier there are those electricians that are very good in their chosen field...........this does not necessarily make them good electricians in the marine field.

I have seen too many stuff ups, too many times, in Port Lincoln, South Australia (was the largest fishing port in the Southern hemisphere), by those who decided to "dabble" in marine electrics/electronics. I am in no way a marine electrician, nor for that matter an electrician of any kind, but I have found problems in vessels that these "dabblers" have missed. This applies particularly to earthing problems and stray electrical currents. I am quite surprised that there has only been one fatality, which I might add is one too many.

I have to teach a bit of basic electrical (E.L.V., low voltage a.c. 240/415v) to the engineers of the fishing vessels, it just falls in the marine engineering courses that I teach. I might add I abhor teaching it, all other areas I have a reasonable base knowledge and "hands on" experience in...........BUT............electrical, I know enough to get by...........just for my own benefit.

I will add that as far as regulations go, the vessel engineers are not supposed to touch anything over 50v a.c. and 120v d.c............anything over these voltages they are to isolate the system and seek the services of a qualified electrician...............BUT,.........in an emergency if crew or vessel safety is an issue, they may try to rectify a problem......NOT GOOD..........but that's the way it is.

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#21

Re: Electric Shocks at Boat Mariner

08/05/2008 2:58 PM

And since you specified that this is a "NEW" facility, you probably should try to get recompensation for any fixes from whomever failed to install the electrical system properly. They may be able to correct it (if you think you can trust them...).

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