ESD /GENERATOR/SHORE POWER WARNING

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barkleydave
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ESD /GENERATOR/SHORE POWER WARNING

Post by barkleydave »

This is not the first encounter I have had while at anchor. Each time it scares me to death!

It has become VERY popular to purchase a portable generator and use it on your boat. I have seen them on swim platforms aft decks etc.

Now here are a couple of real concerns!

1. CO poisoning Not only for users on their boats but gens running close to others while rafting up!

2. ELECTRICUTION! These generators are not part of your internal electrical system. They are a floating ground. If you check the generators there is a safety ground plug Which is supposed to be grounded to a ground stake. NONE OF THESE GENERATORS ARE APPROVED FOR MAINE USE!!
The scenario is simple... bunch of boats raft up... fire up the portables or any genset for that matter for their AC etc... while the kids jump into the water! ONE SHOULD NEVER ENTER THE WATER WITH ANY GENSET RUNNING PERIOD ESPECIALLY IN FRESH WATER!!!!

3. Storing the generator and fuel below decks....

I had to refuse a raft up the other day for the reasons above. I might have lost some party friends but that is a small price to pay for one or another's life.

safe boating,

dave
1987 Marinette 29 FB Sedan
Retired Boat Accident UL and USCG trained investigator
Retired USCG Captain
Dougrose
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Re: PORTABLE GENERATORS "WARNING!"

Post by Dougrose »

I certainly agree that there is a CO hazard with a generator, but I fail to see the electrocution problem.

A portable generator is indeed supposed to be grounded when in use, just as your marina power is. That means that the frame of the generator should be connected to the hull, the neutral out should be connected to the neutral wire to the boat and should also be connected to the hull, and the hot wire should be of course connected to the hot wire to the boat. The generator itself is a "floating" power source, rather like the secondary winding of an isolation transformer, and that keeps the power out of the water. A short or leakage from the neutral wire to the hull will do nothing -- they are already connected. A short or leakage from the hot wire to the hull will pull the breaker and open the circuit. But in no event does current flow from the boat hull through the water to some ground external to the hull, as might happen with shore power, since there is no connection between the generator and objects outside the hull.

When shore power is being used, it is essential to ground the hull to the shore power green wire ground, to prevent current flowing from the hull through the water (and swimmers) in the event that there is a short from shore power hot to the hull, that does not trip the breaker. But, it is important not to provide a DC path for electrolysis, so the shore power green ground must be connected to the hull through a galvanic isolator, which prevents current flow at the low voltages common to electrolysis. All Marinettes were equipped with one at the factory, and they seem to last forever.

Another and better approach is to not connect the shore power green wire ground to the boat at all, but to take the neutral and hot wires to the primary winding of an isolation transformer. The secondary winding is isolated from the shore power, and can be connected to the boat's neutral and hot. Like the generator, the neutral is also connected to the hull, so that a short from hot to hull will pull a breaker.

Note that this is the way the power company does it, except that the "source" of the power is a transformer, usually on a utility pole. A ground rod usually at the base of the pole provides the green wire ground to the customers, and the secondary winding has one end connected to both the neutral white wire to the customers and the ground rod and the other end of the winding is connected to the hot black wire to the customers. It works the same as on the boat: if there is a short from the hot circuit to either the neutral or green ground, the breaker supplying the circuit will open.

All this being said, if you raft up and send power to another boat through an extension cord, which I have seen done, then all bets are off. Current can go out through the cord, and return to its no-longer-isolated source via the water, to the detriment of anyone in it. This sort of thing can be done safely but only with extreme care and not during party hours....
Doug Rose
32' Cabin Cruiser
Twin Perkins 120hp Diesels
Merritt Island, Florida
barkleydave
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Re: PORTABLE GENERATORS "WARNING!"

Post by barkleydave »

I should have used a different title for the initial post.

I am posting a couple of well written articles which should help those understand.

Basicly:

1. Shore power connections use the green safety ground which provides a low resistance path.
2. Generators or inverters use a double pole breaker or switch which breakers the neutral connection.

Plugging a portable generator into your shore power inlet does not break the neutral connection. It still thinks it is operating on a shore based safety ground connection. Most our Big M's have the double pole main. There is also an empty slot for a generator/inverter circuit. I turn my shore power double pole off... and then turn my inverter breaker on which is properly wired as a floating ground. If I go into the water I shut all AC down.

So as to end this thread... understand I am only posting the information. I am not offering personal expertise or opinion for further discussion.

This is a basic and well written article in Boat U.S. addressing basic AC/DC wiring and some of the potential hazards.

Link:
http://www.boatus.com/boattech/casey/sa ... epower.asp

http://www.qualitymarineservices.net/Ne ... 2-2005.pdf

Be safe in the water,

dave
1987 Marinette 29 FB Sedan
Retired Boat Accident UL and USCG trained investigator
Retired USCG Captain
Ryan
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Re: PORTABLE GENERATORS "WARNING!"

Post by Ryan »

Can we get a short answer on this! Like a yes or no.

Is it safe to swim off the back of the boat if a permanently installed generator is running??

Is it safe to swim with a potable generator is running??
1986 32' Sedan
Chrysler 360's
Cleveland, Ohio
barkleydave
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Re: PORTABLE GENERATORS "WARNING!"

Post by barkleydave »

This link should help you make your own decision.
I made mine years ago. NO and NO

The danger exists whether on shore connection, or generator.

http://www.boatus.com/seaworthy/magazin ... lained.asp

safe boating,
dave
1987 Marinette 29 FB Sedan
Retired Boat Accident UL and USCG trained investigator
Retired USCG Captain
aaronrodg
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Re: ESD /GENERATOR/SHORE POWER WARNING

Post by aaronrodg »

OMG! Glad to know about this danger.
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bill
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Re: ESD /GENERATOR/SHORE POWER WARNING

Post by bill »

BigM
Thank You Gentlemen.
Water and electricity don't mix. :shock: Even at the dock. Stay out of the water. :mrgreen:
Stay alive. :D
Enjoy the warm weather that's coming. :roll:
bill
Former owner of
ALUMINATION
Grosse Ile MI
Located on LakeErie
37' F/B Sedan
1975
Twin 360 Chrysler Marine
Raw water cooled
Hydraulic steering both helms
USCG Master Lic. Retired[/color]
Third Owner bill
Fastjeff
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Re: ESD /GENERATOR/SHORE POWER WARNING

Post by Fastjeff »

The only safe way to do this (with a portable generator) is to leave it on the dock, or bow in and put the generator on shore.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington
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