Joe, I think there is some confusion. I’m also guessing that you did not follow the link and read my more detailed blog discussion. I don’t blame your reaction, I would have reacted the same way a little while back.
> > I disagree with this. > I have had a galvanic isolator since about 1995 or so. Mercury Marine sold > them to keep their outdrives from dissolving back then and I grabbed one. I > can go on for a while about how they work, but the short version is every > boat at the marina is wired together by the ground wires and is essentially > one giant boat. If your neighbors don?t have zincs, no problem, your zinc > will cover for them! It may not last long doing triple duty though ? The > galvanic isolator prevents this from happening. First off, I did not argue that galvanic isolators do not work. They do. I stated that the connection of AC and DC grounds is a main factor leading to galvanic corrosion and thus the need for galvanic isolation. The only reason for connecting the grounds is to provide an effective ground-fault current path. Eliminate the need for an effective ground-fault current path, eliminates the need to connect the grounds. Newer technologies provide such a means. I argued that connecting AC and DC grounds is not needed for ground fault protection if the vessel is protected by a ground fault circuit interrupter(ELCI). This why the ABYC E-11 now requires all new vessels to have such a device. The European ISO requirements (see extract from ISO 13297 in my blog discussion) specifically states that if a RCD (another name for ELCI or GFCI) or isolation transformer is installed then '' the negative ground terminal of the DC system need not be connected to the AC shore ground'' . I'm guessing the ABYC will eventually follow the ISO. My main point is that it is wise to install a whole-vessel ELCI. These provide greater safety, and these are now readily available and more affordable than fail-safe GIs. The Blue Seas A-Series ELCI Main Circuit Breaker (model 3106100) which fits my Blue Seas panel costs under $150. Fail-safe GIs cost well over $300. My very robust under $10 DYI GI was installed in what I called a ‘’Fail-Safe installation’’. That is, it was installed between the AC and DC grounds rather than breaking the AC ground to shore and inserting there. The DYI GI, like the Yardina GI, is not technically a ''fail-safe’’ GI, Yardina claims that they have no reports of their GI failing. While these are very unlikely to fail, if it does fail, it does not matter. The only reason I have not yet removed my DYI GI and AC/DC ground connection is that it does not matter. Your discussion below is not correct . Specifically, the statement of ''deadly hazard ‘’. A GFCI/ELCI would cut the power saving one from the deadly hazard. But even without GFCI/ELCI protection, it is more deadly to have a hot wire in one hand and then touch the DC ground if the AC/DC grounds are connected then if they are not connected. That is, a deadly AC current would flow better to the AC ground with the AC/DC ground wire than it would with just an engine to seawater to AC ground connection. The actual reason for connecting the grounds is less for someone on the vessel and more for the safety of swimmers. Yes, it is wise for a vessel without a main ELCI to connect the AC/DC grounds and if doing so then it is smart to use a GI. I would rather rephrase the last statement: it is unwise nowadays for a vessel with AC shore power connection to not have a whole-vessel ELCI. There is a reason why fewer companies are making fail-safe GI. I initially wondered why a company like Blue Seas, which provides practically any electrical need, does not provide a galvanic isolator. But they do have this discussion on their website: https://www.bluesea.com/support/articles/AC_Circuits/88/Green_Wire_%5BControversy%5D <https://www.bluesea.com/support/articles/AC_Circuits/88/Green_Wire_[Controversy]>. For convenience, here is my original link: http://svjohannarose.blogspot.com/search/label/GalvanicIsolator <http://svjohannarose.blogspot.com/search/label/GalvanicIsolator%3Chttps://protect2.fireeye.com/url?k=8c302211-d0a614f2-8c300b66-0cc47adc5fec-d02e08d2e81cb3ec&q=1&u=http%3A%2F%2Fsvjohannarose.blogspot.com%2Fsearch%2Flabel%2FGalvanicIsolator%3E> > As far as not grounding the AC system to ships ground, this would be a large > and dangerous violation of ABYC regs and they exist for a reason. > In a perfect world boats would have isolated 2 wire AC systems with no > grounding at all. This is not the case presently and as long as various AC > devices not built specifically for boats exist we have to deal with potential > ground issues. Do not forget that the shoreside AC power *is not isolated* > and you are floating in a more or less direct connection to the ground rod at > the transformer and/or panel on shore. If some defective appliance puts AC > voltage on any part accessible by a human you now have a hot wire in one hand > and any part of the boats DC ground system is the other half of the circuit. > This can be a deadly hazard on a boat depending on how good the green wire > system on the boat and marina is and even if it is good you still can get a > considerable charge through you. The interconnected grounds prevent this from > happening. > The ONLY way I could see trying to make an isolated AC system besides for an > isolation transformer, which is actually a great idea but big and heavy, is > if the BOAT had an ELCI installed. You cannot count on every marina having > one at their end. > Joe > Coquina > C&C 35 MK I > > - Paul E. 1981 C&C Landfall 38 S/V Johanna Rose Fort Walton Beach, FL http://svjohannarose.blogspot.com/ > From: CnC-List [mailto:[email protected] > <mailto:[email protected]>] On Behalf Of Dreuge via CnC-List > Sent: Sunday, June 02, 2019 4:07 PM > To: [email protected] <mailto:[email protected]> > Cc: Dreuge <[email protected] <mailto:[email protected]>> > Subject: [EXTERNAL] Re: Stus-List Galvanic Isolators > > > > I would not spend much money on a galvanic isolator (GI). The main cause > of the galvanic corrosion is a result of connecting the AC and DC grounds. > Check if you have these grounds connected. Most older and smaller vessels > don?t have the grounds connected and don?t have galvanic corrosion problem. > Also, the industry is moving away from this requirement. > > One is better off investing in a whole vessel GFCI breaker(also called an > ELCI Main Circuit Breaker). These cost much less than a typical fail-safe > GI and provide galvanic isolation from stray AC currents by disconnecting the > power, and more importantly they provide much better ground fault protection > than connecting AC & DC grounds. > > If one still prefers bonding the AC & DC grounds then I would recommend the > Yandina GI or better, a DYI GI, and connect the GI between the AC to DC > connection to provide a fail-safe connection. > > I have a write up on my blog about this and also how to make a DYI GI, but in > short, don?t waste money on an expensive GI, invest your money in an ELCI > breaker, individual GFCI circuit protectors, and a decent marine charger (not > a cheap HF/Walmart/Amazon brand ) > > http://svjohannarose.blogspot.com/search/label/GalvanicIsolator > <http://svjohannarose.blogspot.com/search/label/GalvanicIsolator%3Chttps://protect2.fireeye.com/url?k=8c302211-d0a614f2-8c300b66-0cc47adc5fec-d02e08d2e81cb3ec&q=1&u=http%3A%2F%2Fsvjohannarose.blogspot.com%2Fsearch%2Flabel%2FGalvanicIsolator%3E> >
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