[RE-wrenches] Grounding system for a shack on a frozen lake?

[Nathan Jones]

We have put 12VDC/120VAC systems on many boat docks here on our lakes. The inverter/batteries are the ground as they are the source. We have had several of these structures take a lightening hit and in all cases our equipment has survived. The only clue is a blown fuse between the solar panel and the charge controller. My guess is the metal structure of the dock framework is acting like a Faraday cage and routing the strike to the water via the anchoring cables. 
The voltage from the inverter will not flow into the water as there is no return path to source there. As long as all sources of potential are bonded back to source there is only shock hazard by getting between hot and neutral.
Also, if a fault does occur with proper bonding the system will drain itself to dead fairly quickly and a summary diagnosis should find the fault as the culprit.
Nathan Jones
Power Source Solar
417-827-0738

On Wed Aug 10th, 2011 5:30 AM CDT Christopher Warfel wrote:

>We have developed some off grid 12/24/48 Vdc and dc/120Vac systems for use in aquaculture that are basically in the tidal of estuaries, far from shore.  We have attempted to create a earth coupled ground by grounding the system to copper conductors looped in the salt water.
>
>On 8/9/2011 8:40 AM, Dave Click wrote:
>> Per 690.41 you probably wouldn't need to ground it for a system like this, but I like the idea of dropping a ground rod down into the water. Then curve the end and find a big worm, of course.
>> 
>> **
>> 690.41 System Grounding. For a photovoltaic power source, one conductor of a 2-wire system with a photovoltaic system voltage over 50 volts and the reference (center tap) conductor of a bipolar system shall be solidly grounded or shall use other methods that accomplish equivalent system protection in accordance with 250.4(A) and that utilize equipment listed and identified for the use.
>> **
>> 
>> On 2011/8/9 8:34, Drake wrote:
>>> That is an amusing concept, and it sounds like a fun project. Why not
>>> poke a hole in the ice and drop the rod in the water? If the water is
>>> not too deep, send it to the bottom. It certainly will be below the
>>> permanent moisture level!
>>> 
>>> 
>>> At 01:34 AM 8/9/2011, you wrote:
>>>> Sounds like a silly question but is there any way to ground a small
>>>> battery based PV system serving a temporary fishing shack on the
>>>> middle of a frozen lake? Around here they call these 8' x 8' (or
>>>> larger) shacks "ice houses". One or more holes are augered through the
>>>> ice for fishing lines. Some of the shacks get remarkably fancy, almost
>>>> luxurious (in a guy kind of way). There is usually plenty of beer and
>>>> snacks. Sometimes fish, too. The shacks get set in place as soon as
>>>> the ice is solid (4-6" thick) and they may stay there for several
>>>> months. It's a home away from home for a lot of upper midwest folks in
>>>> the winter. Some like the idea of a small solar powered battery system
>>>> for light, CD player, TV, etc. There's no earth around for hundreds of
>>>> yards, even miles.
>>>> 
>>>> Charlie Pickard
>>>> Aladdin Solar
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>>> Drake Chamberlin
>>> ATHENS ELECTRIC
>>> OH License 44810
>>> CO license 3773
>>> NABCEP Certified PV
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>
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>Christopher Warfel, P.E.
>ENTECH Engineering, Inc.
>Energy Utilization Experts
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