aluminum hull boat grounding

[liebler]

I have a 1985 house boat with aluminum hull. When I installed a generator 2 years ago, the code called for isolating the hull from ground. I understand the 2003 NEC now calls for grounding the hull through shore power cord to the power post. I am not an electrical engineer, but I am a mechanical engineer with industrial machinery experience. Grounding the hull seems wrong to me as it's a sure way to cause a voltage between the hull and the water, thereby being a safety problem for swimmers boarding the boat, as well as cause electolosis problems in the hull material.
Can you tell me reasons for changing the code to include grounding the hull? Are there any safety problems with not grounding the hull?
Thanks!

 

[don_resqcapt19]

Re: aluminum hull boat grounding

First, there is no 2003 NEC. The current edition is 2002 and the next one will be 2005. Second the NEC does not apply to boats.

90.2(B) Not Covered. This Code does not cover the following:
(1) Installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles

Don

 

[liebler]

Re: aluminum hull boat grounding

House boat manufacturers tell me they are tearing out their hair because the Coast Guard is requiring them to follow NEC 2003, Article 250, related to grounding.
I called the Coast Guard, who refered me to NFPA 70, which is the NEC, and told me to use the 2003 version.
I'll try going back to the Coast Guard on the question. Any further advice you could provide would be appreciated.
Thanks!

 

[dereckbc]

Re: aluminum hull boat grounding

There is no 2003 NEC. However grounding the generator to the hull would not induce a voltage between the hull and water. Not sure about electrolosis as this is usually associated with DC and not AC.

As Don has stated the NEC does not cover boats. But it does cover Marinas in article 555. And if you are supplying power from the Marina to the boat then NEC requirements would need to be followed.

[ June 09, 2003, 07:43 PM: Message edited by: dereckbc ]

 

[roger]

Re: aluminum hull boat grounding

Liebler, go back to Don's post, there is no 2003 NEC. Now take Don,s reference to 90.2(b), the NEC (NFPA 70) does not have any jurisdiction over the wiring on your boat. As Dereck points out, it does however cover the dock wiring. (555)

Now if you must follow the Coast Guards rule, (that you follow the NEC) do just that, and don't do anything.


Roger

[ June 09, 2003, 08:01 PM: Message edited by: roger ]

 

[hornetd]

Re: aluminum hull boat grounding

You can insure the safety of swimmers, prevent electolysis, and keep the Coast Gaurd happy by transferring the neutral and the equipment grounding conductor between on board and shore power. Use a nonmetallic cable or raceway system and non metallic boxes and you will have created a double layer of insulation between the current carrying conductors and the hull. The cheapest way I know of to do the transfer is to cord and plug connect the onboard wiring to either a shore line extension cord or the onboard power source. That way when the cord is connected to shore power there is no conductive pathway between the hull and the shore.
--
Tom

 

[hurk27]

Re: aluminum hull boat grounding

The Coast Guard should stay with saving boaters lives and not get into boat wiring.
as far as I know the ABYC is who set's the standereds for boats.
the Galvanic Isolator is the way I would go this way you can be sure that you metal hull is isolated.
here is a photo of one:

the web site is :
http://powerboat.about.com/gi/dynamic/offsite.htm?site=http%3A%2F%2Fwww.yandina.com%2Felectrolysis.htm

 

[gwz2]

Re: aluminum hull boat grounding

Is it / would it be third party tested ( Listed ) ?