I am getting ready to buy a Classic 150 for an array on a boat. I would like to add lightning protection if possible. Trouble is, there is no ground on a boat. Ground rods are easier to drive into water than into soil but don't do much good. :D I have heard of a so-called "chassis ground." That might sound good since I have an aluminum hull. The trouble with a "chassis ground" is that boaters go to great lengths to keep electrical currents away from their hulls. Galvanic corrosion from electrolysis can eat a hull quickly.
Is there some way to add lightning protection without a ground or should I give up and take my chances?
Quote from: Endurance on April 17, 2013, 05:26:42 PM
I am getting ready to buy a Classic 150 for an array on a boat. I would like to add lightning protection if possible. Trouble is, there is no ground on a boat. Ground rods are easier to drive into water than into soil but don't do much good. :D I have heard of a so-called "chassis ground." That might sound good since I have an aluminum hull. The trouble with a "chassis ground" is that boaters go to great lengths to keep electrical currents away from their hulls. Galvanic corrosion from electrolysis can eat a hull quickly.
Is there some way to add lightning protection without a ground or should I give up and take my chances?
http://boatsafe.com/nauticalknowhow/lightning.htm (http://boatsafe.com/nauticalknowhow/lightning.htm)
The boatsafe piece was great reading. Great stuff for protecting boat occupants. There is, of course, no problem grounding things like a mast or a metal frame to a metal hull since masts and metal frames don't produce any stray current. But grounding solar panels or a charge controller to a hull might be asking for trouble. I guess what I'm wondering is if a surge protection device like a MNSPD-115 will do any good to protect my charge controller if the ground wire is either attached to 12v negative or if it isn't attached to anything.
The AC ground and grounding system on marine vessels are floating at sea, meaning that they do not ground on the vessel, but only to shore power.
There is only one point in marine where the DC side is grounded, and that is at the battery. It, too, is a floating system in which nothing is ever grounded to any metallic part of the vessel, most especially not the bonding system.
The bonding system has nothing to do with electrical systems. Underwater metals are simply wired together to equalize differences in potential of different kinds of metal. Nothing in the electrical system must ever be grounded to the bonding system. Unfortunately, some people don't understand this and use it to ground electrical equipment, usually with undesirable results.
There is only one bond between the DC and AC systems in marine applications, and that is at the inverter chassis bonding lug to battery negative. The last thing you need in a boat is a hot wire accidentally touching part of the hull that has been bonded to DC negative and causing a fire.
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Chris
Thank you for the excellent insights. They come at a good time since I will be installing a new aluminum-framed party top on my houseboat in the next two weeks. The one I am taking off didn't have a lightning protection wire to tie it to the houseboat's aluminum pontoons. But the new one will.
I spoke with Robin by phone who assured me that there was way too much resistance in a surge protector to ever allow current from the current carrying side of the surge protector to leak to the hull-ground side. That sounded good to me since the only way the wire grounded to the hull would ever carry any current would be if I got hit by lightning. The chances of that are as low as, well, being hit by lightning.
I was all set to go this route until I remembered the little LED indicator that tells the user that the surge protector is working. I'm thinking that the little LED has to be grounding somewhere. If that "somewhere" is my hull, I'd need to disable it.
Ryan, would you mind sharing your thoughts on this? I am planning to buy my equipment on Monday and would like to know whether to include a surge protector in the system.
You might want to check with a marine surveyor or marine electrician on that one. I don't think anything in the boat's electrical system (such as solar panel frames or even a surge protector for electrical equipment) can be tied into the boat's bonding system.
In our boat, for instance, even the onboard Yanmar diesel generator has a floating neutral and floating ground, and they are only tied together when hooked into shore power where the ground goes to actual earth ground - but still separate from the boat's bonding system. The generator is isolated from the hull with rubber mounts, and so are the propulsion engines. The shafts going from the engines to the V-drives have rubber isolators in them.
There's annodes on the rudders and on the prop shafts under the prop nuts, and also on the bow and stern thrusters.
So I don't really know about that. You got any other boats at your marina that have solar on them, that you can go visit to see how it was done?
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Chris
in my view you can connect the grounded end of the spd to the hull. this is not your electrical ground for power and the leds will not light unless they have the electrical system already tied to the hull as ground. you are simply making a path through the movs to the hull in the case of a lightning potential only. one lead would connect to the +, one lead to the -, and the ground lead to the hull and not the - of the electrical system.
My grounds all float like Chris said. I've disabled the Ground Fault in the Classic and don't have a surge protector since lightning is very rare here in fact rain has been rare here this year also. L