Grounding/bounding

[MikeP]

To avoid further corrupting the shower head thread with this stuff...

I found a very interesting article that essentially says the opposite of what most stuff on this site says about bonding. It says NOTHING should be bonded and all in-water metal components should be isolated from each other.

http://www.kp44.org/ftp/MarineGroundingSystems.pdf

and here's another good one:

http://www.onemanonline.com/Technica...20Systems.html

Of course there are tons more but I think they are helpful. One says bonding everything shouldn't be done, the other doesn't go that far but says it's controversial as to whether it's a good thing or a bad thing.

Obviously Hatt felt it was important that all components be bonded.

[Maynard Rupp]

In researching problems with our boat, I have found Hatteras to be extremly conservative. They won't stop the shore power green wire at the isolation transformer. They cary it through to the bonding system. This makes our isolation transformers into polarity transformers. They won't budge on this. They don't want us to install galvanic isolaters either. They agree that this will solve our electrolysis problem, but are concerned that we won't have a shore ground in the event that the galvinic thing fails open. My air conditioning pump was factory wired to run anytime even when "fan only" is seelected on the AC control panel. My wiring diagrams show it that way. I re-wired them to only run that cooling pump when either compressor is on.

[stormchaser]

Several of my previous boats had no bonding system. Honestly, I see no real advantage to it other than yet another thing to maintain. But since it is there and the boat was designed to have it, I will of course keep it and maintain it.

[SKYCHENEY]

Does not a bonding system create a way to dissipate the power from a lightning strike?

[bostonhatteras]

the problem with de-bond and isolate is that it is a theory only proposition. it is virtually impossible to have all metal completely isolated from each other, allowing each piece to reach its electrical voltage potential all by itself. is that propellor really isolated from the shaft? or are the rudder and rudder stuffing box/thrust bearing exactly the same alloy? how about the engine cooling seacock and its through hull are they the exact same alloy? sure its bronze but i doubt very much that china bronze is the same as what came out of american foundries 30 years ago. its easier and a surer bet to tie everything together and let the zincs do the worrying!

[TedZ]

In researching problems with our boat, I have found Hatteras to be extremly conservative. They won't stop the shore power green wire at the isolation transformer. They cary it through to the bonding system. This makes our isolation transformers into polarity transformers. They won't budge on this. They don't want us to install galvanic isolaters either. They agree that this will solve our electrolysis problem, but are concerned that we won't have a shore ground in the event that the galvinic thing fails open. My air conditioning pump was factory wired to run anytime even when "fan only" is seelected on the AC control panel. My wiring diagrams show it that way. I re-wired them to only run that cooling pump when either compressor is on.

Boy is this confusing. Where was this info when we were passionately arguing about this topic? The isolation transformers on Hatteras's have a continuous green wire bond from the shore to the green wire bond on the boat? I agree with that as do the WORDS of the ABYC but i don't remember anyone else supporting that electrical design philosophy. Of course that answers the long shore power thread also. The CG supports this design to avoid drownings. They have done an extensive report on the subject that the no-green-in-the-shore-power-cord folks should read. A chilling report but too long to attach here. Im sure it can be Googled. I have a search term if anyone wants it.

As for Mike's reports? They are interesting opinions of Electrical Engineers just like mine are, BUT it depends on the design goals. One way you are worried about people. Another, metal on the boat. Yet another, swimers and damage to the metal on your and adjacent boats. All of these masters cannot be served simultaneously.

My continued position is to be safe for the people on the boat, in the water and on the dock first and formost. That and use a ton of GFI's and other newer fault detecting devices. There is no question that that design is not optimal for noise or for protecting your boat's metal.

Ted

[Maynard Rupp]

Yes Sky...The most important reason for good and large bonding wires is to provide a path to ground for lightning. A friend has a new Mainship 40. He was in the final 5 locks on the Erie Canal when they saw a big bthunderstorm coming. They tied up and were talking to a young man who was on shore. Lightning struck and killed the young man. Many of his crimped wire ends blew up because they wern't crimped well enough. His thru hulls all siezed and lost pieces of metal. All electronics and compasses were ruined. When Mainship repaired the boat they added a better ground bonding system.

Ted is right on. You can't protect people, through hulls, and anodes at the same time. Hatteras does carry the green wire to the isolation transformer, but then they bond the case of that unit to the bonding system. Simply said, If you check continuity between your boats green wire connection on the shore power plug and ,say, your rudder post, you will find a complete, (no resistance), circuit.

[Maynard Rupp]

Boy is this confusing. Where was this info when we were passionately arguing about this topic? The isolation transformers on Hatteras's have a continuous green wire bond from the shore to the green wire bond on the boat? I agree with that as do the WORDS of the ABYC but i don't remember anyone else supporting that electrical design philosophy. Of course that answers the long shore power thread also. The CG supports this design to avoid drownings. They have done an extensive report on the subject that the no-green-in-the-shore-power-cord folks should read. A chilling report but too long to attach here. Im sure it can be Googled. I have a search term if anyone wants it.

As for Mike's reports? They are interesting opinions of Electrical Engineers just like mine are, BUT it depends on the design goals. One way you are worried about people. Another, metal on the boat. Yet another, swimers and damage to the metal on your and adjacent boats. All of these masters cannot be served simultaneously.

My continued position is to be safe for the people on the boat, in the water and on the dock first and formost. That and use a ton of GFI's and other newer fault detecting devices. There is no question that that design is not optimal for noise or for protecting your boat's metal.

Ted

Ted, I believe that a galvanic isolater helps us serve several masters by rejecting only very low voltages on the green shore wire. Mine allows passage of all voltages > 1 1/2 volts.

[sgharford]

In regards to bonding based on info in article Mike posted (thanks Mike! - good reads - Practical Sailor, Oct 15th, 1996 - Page 3) - the author appears to make a good case as why not to bond for sake of galvanic corrosion in a marina with potential stray currents. He states “If your bits of immerses metal are bonded, the electric current will take the lower resistance path offered by your boat in preference to the water near your boat and the current will flow into one of your bits of metal, through your bonding wires, and then out another bit of metal”. As my boat spends 97% of its time at the marina when in the water and discounting safety of swimmers and lightning protection, would most agree that bonding be more detrimental to galvanic corrosion? Galvanic isolators and Isolation transformers only separate your boat from your neighbor’s boat(s) and would not protect in scenario given by author. I guess the only real way to answer that is to determine if there are in fact stray currents in water surrounding the boat.

So what I am wondering is – Is there a reliable way to test for stray currents actually in the water around your boat?

[Pete]

Just to keep all the facts in front of us, many isolation transformer Hatteras boats, including mine, do not carry the shore ground beyond the stainless mounting plate for the shore power inlet connectors. This wiring configuration only carries the X and Y hot legs from the 240 connector and the X and N wires for the 120 connectors to the isolation transformers. The isolation transformer case grounds are tied to the bonding system as are the boat internal green wire ground and the center taps of the transformer secondaries. This approach keeps all the internal metal objects in and on the boat at the same potential and also keeps any stray voltage on the shore green wire out of the internal boat system. I would put this system in the "best protection for the boat and anyone on it" category. From earlier post, Hatteras must have had more than one approach to handling the shore green wire, on boats with isolation transformers. Perhaps driven by the ongoing changes that ABYC publish.