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DC Ground

T

terry_thatcher

Terence Thatcher
I am doing some electrical work and I cannot find any substantial ground wire leading from the breaker panel (or the bus bar in the bottom of the chart table where all devices grounds terminate.). There is a number 8 red wire feeding juice into the panel, but no black number 8 wire leading out. Everything works, but this is confusing. the old manual only explains the hot wires, not the ground, so that doesn't help. I am contemplating running a 6 wire from the bus bar back to central ground post, then on to the engine, to make myself more comfortable. But there MUST be at least a number 8 wire running from the panel back to central ground, but I will be damned if I can find it. Can anyone help? Yes I know I could hire some one to install a new panel, but I don't want to spend that money right now. I am having the AC system upgraded, but the DC will have to wait. Thanks
 
Terry
What if you work from the house battery bank out? See if you can find a wire or wires that are connected to a negative terminal on the battery/batteries going out towards the 12V panel. My 12V system has long since been reworked so I don't remember the original wiring. There should be a connection from the 12V panel back to the battery bank of equal size to the feed wire.

Jim
 
Terry, On my system there are two grounds that go from the panel to the starboard ground busbar in the engine compartment right under the access panel. One is the ground for the panel indicator lights and the other is a panel face ground. Someone had connected the ground to the voltmeter mounting clamp which is aluminum,needless to say I could not take a meter and measure continuity to the panel face because of corrosion. I ended up installing a bolt on the panel face,after scraping off the paint, and installing the wire there. I did not look under the nav station desk to see where the wire was connected to on the terminal strip.
 
terry_thatcher said:
I am doing some electrical work and I cannot find any substantial ground wire leading from the breaker panel (or the bus bar in the bottom of the chart table where all devices grounds terminate.). There is a number 8 red wire feeding juice into the panel, but no black number 8 wire leading out. Everything works, but this is confusing. the old manual only explains the hot wires, not the ground, so that doesn't help. I am contemplating running a 6 wire from the bus bar back to central ground post, then on to the engine, to make myself more comfortable. But there MUST be at least a number 8 wire running from the panel back to central ground, but I will be damned if I can find it. Can anyone help? Yes I know I could hire some one to install a new panel, but I don't want to spend that money right now. I am having the AC system upgraded, but the DC will have to wait. Thanks
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Terry
Would it be possible for you to take pictures and post them so we can see what you have going on? It would help.
 
Terry,
The actual DC ground on a boat is the (-) terminal of the battery. All current comes from and returns to the battery. Your best solution is to take a #4 cable from the (-) terminal to the bus bar where all your grounds are attached. If you have original wiring, run a #8 wire from the negative bus bar in the engine compartment to you negative distribution bus bar in the chart table. Make sure you have a good connection between the (-) terminal on the battery to the engine compartment bus bar. Last but not least, beware of AC vs DC circuits. AC hot is also black.
 
Terry
What Jose just alluded to and I have said on this board many times, the original wiring on the Morgans was so poorly done as to be dangerous. You would do well to read up on ABYC standards and upgrade your systems, both AC and DC, to more modern and safe configurations. The ground buss bar in the engine compartment is in a location that is subject to salt water spray from the prop shaft. It is therefore exposed to high levels of corrosion. If your negative wiring from the 12V house panel is routed through that buss bar, you should reroute it more directly to your battery bank.

Jim
 
What sort of things originally connected to the buss bar in the engine compartment? I am aware of that buss bar, but haven't gotten to exploring or relocating it.
 
Looking at the drawing of the engine compartment ground buss on Dana, I find 5 wires still terminated there. The ground wire to the engine block (size AWG 14), 12V panel ground (AWG 10) ( this wire no longer carries the 12V return to the battery), fuel tank ground (AWG 12), engine ignition switch (AWG 14), a AWG 10 that runs forward that I never found out where it leads to. Two wires that I remember removing from the buss were the ground wire from the 110V disconnect switch under the cockpit coaming and the return wire for the engine compartment blower. I hope this helps.

Jim
 
It helps in that I know I need to look closer. Eliana has been re-powered with a Volvo. The engine block is isolated (or is supposed to be) from ground. I do not believe that buss connects to the engine block. I think that it was was moved to the battery. It is possible that the only active circuit I have there are is the blower. In which case I will remove that buss and all the old wiring.
 
Warren
Do you have a Drivesaver disk in your prop shaft coupling? It truly isolates the engine from the sea.

Jim
 
jimcleary said:
Warren
Do you have a Drivesaver disk in your prop shaft coupling? It truly isolates the engine from the sea.

Jim
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No. Should I? What about salt water through the heat exchanger? The heat exchanger is bolted to the Engine. One concern I have is that there is also no anode in the exchanger. Supposedly it isn't needed with the engine block isolated from power. But if the heat exchanger is damaged, it is very expensive and difficult to replace. I question in my mind if I should drill and tap a hole in it for an anode.

More on topic, I am planning to rework the battery compartment sometime soon, with a negative buss, and two positive buses, instead of everything terminating at the battery terminals. I sounds like I should abandon the buss that will literately be inches away on the other side of the wall the the engine compartment.
 
Warren
I'm talking about the engine being electrically isolated from the sea. Not the corrosive effects of salt water in the cooling system. The heat exchanger and the exhaust manifold are isolated from the sea electrically by the rubber hoses on the intake and exhaust sides. The Drivesaver is a 1" plastic disk that fits between the halves of the shaft coupling that performs two functions. First it insulates the metal of the shaft from the metal of the engine, breaking the flow of electrons to the sea. The other job is to act as a fail point in the case of an abrupt stopping of the shaft. If a line gets tangled in the prop, the Drivesaver will fail before damage is done to the tranny or the engine. If that happens it's an easy fix to remove the Drivesaver, rebolt the coupling together, and continue on your way. Cheaper to replace the Drivesaver then the engine.

Jim
 
Maybe I am missing something. The exchanger is an integral part of the exhaust manifold bolted to the engine. It is connected electrically it to the engine.Sea water flows through the heat exchanger. So the exchanger is electrically connected to the sea, the sea making direct contact to it. If the exchanger were not bolted to the engine but instead external with rubber hoses connecting it to the engine then it would be isolated. At least that is my understanding, and why this engine is isolated. The starter, alternator, and all sending units have a ground attached and none are electrically connected to the block.

Definitely worth the look at the Drivesaver. What material are the bolts?
 
Warren
Water is not a good conductor of electricity. The impurities in the water are. Sea water is a better conductor than fresh water. The electrical connection via the water in the engine is tiny compared to a direct metal to metal contact provided by the shaft and prop. Our boat lives on a mooring, rarely ties up at a dock, has a Drivesaver and does not use or need zincs on the shaft. In 29 years that we have owned Dana, we have replaced the prop once. Without the Drivesaver the electrolysis would have required zincs and would have resulted in heavy barnacle growth on the prop. If a boat lives on a dock with a shore power system then the electrolysis comes from a different source and not the boat itself. In that case, to combat the stray electrons, the boat will need zincs or maybe a galvanic isolator, depending on how severe the leakage from the dock is.
The Drivesaver comes with the bolts need to do the install. They are offset so the bolts do not touch the opposite side of the coupling. The bolts are stainless steel.

Jim
 
I hate to raise the subject but I need help on making sure I have the DC grounded before I splash.

Question 1: In the engine compartment, there is a buss mentioned in this thread. I had a strange wire that was curled in loops but was not connected to anything at this location. So I think this wire was connected to the engine. Am I right? It was not a heavy gauge wire so I replaced it with a heaver gauge and attached it to the bolt that bolts the transmission to the engine. Was this right?

Question 2: The same kind of wired was also attached to the metal plate on the fuel tank. I think that was once connected to the fuel fill fitting under the deck. Is that necessary? It is no longer connected. This question I think is more of a "bonding" issue rather than grounding and if so, would that connect to anything on the motor?

Question 3: Back to the ground buss in the engine room. I have two shore power connections on the coaming of the boat. On one of them, It appears that I have the neutral and the ground wire from the AC connection on the stern of the boat where you plug in from shore power. Is that right.? Would DC and AC use the same ground buss bar. I think that shore power connection is for the Air Conditioning.

Question 4: in reading this thread, is the negative post of the battery is to connect to this buss? I have two batteries, do both need to connect.

I guess I need to get someone with expertise to look at all of this for me but some of the wiring has been changed, moved or disconnected with all of the equipment that used to be on this boat over the years before me. Should I hire someone to look at this?
 
YES, I would recommend you get an electrician to check it all out. problems in DC can be inconvenient. Problems with AC can be dangerous. Original Morgan AC stuff would not pass today, I suspect. I had my AC and some of my DC reviewed and improved by a professional.
 
John,
I can recommend a great ABYC electrician from Mandeville. He re wired my boat several years ago. He is very professional and will travel for jobs. He has worked on several M38s so he’s quite familiar with our boats. Please let me know if you’d like his contact information.
 
John
Question 1 -- Yes, the engine block needs to be grounded to that terminal strip with the squiggly wire. There will be a number of wires ending at that terminal board. The 12V negative from the panel, the ground wires from the 110V connection fittings, the wire to the fuel tank plate, plus others.

Question 2 -- There should be a wire (#10 awg) from the diesel fill fitting on the deck to the metal plate on the tank. This is to disperse any static electricity that can build up from the flow of liquid from the nozzle. When filling the tank, the metal nozzle should be kept in contact with the metal of the fill fitting.

Question 3 -- Those wires from the 110V system to that buss bar are the people protection system. If a hot leg of the system fails and touches a grounded part of the system, the circuit breaker will blow before someone gets electrocuted (we hope).

Question 4 -- The negative posts of the 12V batteries do not need to be directly connected as long as the negative side of the 12V panel is connected. Although, that may be different with the new ABYC rules with which I am not up to date on.

Terry and Tommy have the best advice. Get a good ABYC qualified electrician to go over your systems. Times have changed. The original 110V system in our Morgans was grossly inadequate. Also, treat every piece of the original wiring with suspicion. There is what is called creep corrosion. That is where an old wire gets corrosion up under the insulation, away from the terminal fitting. You won't see it unless you strip away the covering. This corrosion, at best, will cause higher resistance in the wire, at worst, can cause overheating and fire. ABYC recommends only tinned wire. None of the original wire on the boats was tinned.

Hope this helps somewhat.

Jim
 
Thank you very much Jim for this information. This is starting to make sense now. I just could not see how the AC neutral and negative wires and DC neg wire would go to the same neg buss bar as it is connected. So apparently that is correct. By the way, would not the engine having been connected to the buss direct the neg current to the shaft and then into the water? is that right? I appreciate the time you spent on the response. I will also try to find someone with those credentials to go thru the DC and AC wiring.
 
John
If either the 12V or the 110V systems are properly installed and wired, then there will be no current flow through the grounding wires. It is only when there is a failure of the return wiring that a current would flow in the grounding wires. The results of such a failure could be anywhere from annoying to catastrophic. As our boats get older and the wiring begins to show it's age, this can become a serious problem. While it's not a solution to the problem, a Drivesaver (talked about earlier) is a major deterrent to the flow of stray currents to the sea. It electrically isolates the shaft and prop from the engine.

Another system that needs to be considered is the lightening grounding. Some boats have all their metal objects, mast, shrouds, engine, thruhulls, etc, connected together in the hope of leading a lightening strike thru and out of the boat without it doing much or any damage. While this works, the system also provides a path for stray currents to find a path to the sea. In my opinion, lightening grounding is a "damned if you do, damned if you don't" proposition. But that's a story for another discussion.

I think calling Tommy McNulty's electrician would be a good plan for you.

Jim
 
Jim, again thank you for this advice and further explanation of our boats and what I should be looking out for. I will also look at a shaft saver as well. I will make the call to an electrician that is qualified. It's not only me on the boat but family and others, so I need this done right.
 
You should also ask the electrician to install what I think is called a galvanic isolator on your AC inlet to the boat. Protects from bad dock wiring and protects, I think, those in the water near your boat. Jim, I have a drive-saver and the previous owner installed a shaft brush grounded to the engine negative busbar. Do I not need that?
 
Terry
A galvanic isolator is a 1:1 isolation transformer that takes the 110V from the dock and gives you 110V on your boat without the ground connection from the dock. This is a good thing for the boat if the dock system is bad and has leakage. But there are other ways for stray current to enter the water near your boat. Your 12V and 110V systems may be perfect, but if your dock mates systems are faulty, he may be putting current into the water that can cause electrolysis to attack the metal fittings on your boat. A good friend of mine had the prop and strut on his Freedom 36 destroyed in less then a season at a dock from his neighbors 12V system.

The Drive Saver does two jobs. It isolates the shaft and prop from the engine electrically and adds a point of failure in the shaft to protect the transmission. If a line get tangled in the prop and abruptly stops the shaft, the Drive Saver bolts will shear out saving the tranny and engine. Don't ask me how I know this works!! It's cheaper to buy a new Drive Saver for $200 then to replace the tranny. Electrically, by adding a shaft brush to the shaft after the Drive Saver you are defeating it's isolation benefits. I'm not sure what the reason is for your shaft brush unless it has to do with a lightening ground system. Someone with more knowledge then me would have to advise you on that.

Jim
 
Terry I believe that the galvanic isolator being mentioned above is a device that is placed between the boat's AC-Gnd(Earth) and the DC ground. Usually it is made up of a combination of four diodes. This allows for about 1.2v differential between the two grounds so as to discourage stray currents, while at the same time providing a path to ground(that will trip the breakers) in case of a fault.
 
tfrere said:
John,
I can recommend a great ABYC electrician from Mandeville. He re wired my boat several years ago. He is very professional and will travel for jobs. He has worked on several M38s so he’s quite familiar with our boats. Please let me know if you’d like his contact information.
Click to expand...
tfrere said:
John,
I can recommend a great ABYC electrician from Mandeville. He re wired my boat several years ago. He is very professional and will travel for jobs. He has worked on several M38s so he’s quite familiar with our boats. Please let me know if you’d like his contact information.
Click to expand...
Tom,

Lucy Maria Dunia, a Morgan 383 is docked in Hernando Beach, FL 34607, about 50 mikes north of Tampa Bay. I googled ABYC electricians for that zip code and got no results within 100 miles. What's the number for your contact maybe I can get a referral. Also, I have an installed drivesaver and the shaft connector is very rusty. The transmission/engine side is fine. I replaced my standing rigging in January 2018 and connected an external fish to the aft stay. The gator clip on the fish is completely rusty but the aft stay is just fine. No signs of corrosion.
 
I have read closely the article from Rick. Eye opening. Getting the AC wired correctly is without doubt, a serious matter, I am sure we all appreciate that. I will get the AC ck'd out by qualified electrician for sure. However, I picked up on one item in the article that appears to me to be in conflict with my wire or for that matter wiring we may all have in mine is typical. The Negative buss in the engine compartment connects neutral and negative AC wires and also provides the connection for the negative DC wires on the same buss, which in turns connects to an engine bolt for grounding. The article states that this would not be in compliance with ABYC standards, that is to say a boat should not have the same buss connecting both having AC and DC grounding together. At least that is how I read it. Plus the article strongly recommends bonding. It concedes that bonding unfortunately promotes electrolysis, but it stops possible transmission of a hot AC current to a person or into the water in the event a hot wire shorts out on a metal item. This would happen if a hot AC wire is nicked or the insolation is frayed against metal that can be touched or is contacting the water which would be very serious. Bonding would somehow channel the current to a ground. But would that mean every thru hull would need to be wired together along with the fuel tank plate an the air conditioner? Interesting, the article doesn't state what or where the bonding wires connects to to ground it. Is the Engine the ultimate ground for DC? Is the Engine the ultimate ground for AC?

On another subject, an isolation transformer does not seem practical. The articles states that they are costly, large and heavy and only gives limited protection. The galvanic isolator on the other hand, something that Jim has referred to, seems much more practical. If one of those are used between the couplers, does not the space it requires to break conductivity, push the prop back a couple of inches. I don't think I have much room than that before the shaft hits the stock. In any event, I am out of my element now and appreciate indulgence from the reader of this post. Just trying to understand what is going on with everything on and in my boat. Thanks. I'll be quite now.
 
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John
The Drive Saver that I speak about is not a galvanic isolator. The galvanic isolator is a piece of electrical gear who's job it is to separate the ground from the incoming 110V (dockside) system from the ground on the boats 110v system. It is a smaller version of the isolation transformers used in places like hospital operating rooms to insure that the person being operated on isn't shocked by the electrical equipment the doctor is using. The Drive Saver is simply a plastic disk (1" thick) that breaks the electrical connection between the engine and the shaft/prop. They are two distinctly different things.

There is a tremendous amount of confusion with the differences between 110V grounding, 12V grounding, bonding, Lightening protection and the prevention of electrolysis attacking the underwater metals. When Morgan build our boats, there was little common information about integrating all these different grounding and protection systems. The original 110V system that was installed on our boats was a highly dangerous accident waiting to happen. As a construction electrician I realized the danger and completely removed all of the 110V system. That could be done because the boat lives on a mooring and rarely goes to a dock with 110V.

As time passed, the ABYC standards were set up to regulate the way all boats were wired. With safety of the people on the boats as the primary concern. I think if you research those standards and locate an electrician who really knows those standards you will be happier. Maybe a bit poorer, but happier nonetheless.

Jim
 
I appreciate your expertise Jim. I knew you must have a background in this area from your posts. I will be in a slip soon if the splash ever happens and so here in the gulf south, air conditioning is important if you spend anytime on it while not sailing and so shore power will have to co-exist with DC so I will find the right guy to conform my AC on the boat to ABYC stds. Thanks for your input!
 
My contact ABYC electrician is David Mogar. His telephone number is 907-399-1625. Emai electric@xyz.net. I can tell you he is one of the best. He is based in Mandeville, LA (north of New Orleans). His phone number is from Alaska where he lived until about 7 or 8 years back. David is originally from Northern California. He was the electrician for many of the boats on The Deadliest Catch television series. He is very professional and knows boats inside and out. He is also a sailor with a 35’ Coronado.
 
Thanks Tom, I missed seeing your earlier post on this thread. Thanks for responding. We do need to meet up one day as we planned a year or so ago. Got busy with work and grandbaby in Austin since we last talked. With the number times gone to Austin, I can drive to the NO airport with my eyes closed. I don't know an electrician for this so I will give David Mogar a call. Are you familiar with Laborde Marine in Mandeville, they worked on my transmission, good job but they alone set back my retirement plans $$$. Thanks!
 
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John,
Yes, I have purchased quite a bit from Labordes over the years. They are the Yanmar distributor in our area. When I bought my Yanmar 3JH4E (it was removed from a new boat with 250 hours), the previous owner gave me 30 days to verify its condition. Labordes checked it out for me and I paid them well to do so. They are very good and know their business but very pricey.
From your posts here it sounds like you are nearing completion. Will you be splashing soon?
I have not sailed this year like I have in previous years. In fact, my boat hasn’t left the dock since June. I used to take it out twice per month. The main reason is I retired from my company of 38 years and began working for an Engineering/Survey firm. My travel for work has increased significantly and traveling 2 hours each way to the boat has suffered.
You will be very happy with David. He knows our Morgans well as he has worked on a few here in Mandeville. He does his work the right way the first time and provides drawings of his completed work. He’s not cheap but he will only do what you need him to do. Keep in mind though, as Jim stated, the original wiring in our boats was not tinned and is probably in pretty rough shape by now. David and I pulled all of the old wiring (AC and DC) out of my boat and did a complete rewire, panels, breakers, buss bars and all. I decided to replace all lighting inside and out with LEDs at the same time.
Good luck
 
Gentlemen -

I have a question that seems to dovetail with this discussion that I could use some advise on.

I have a copper strap connected to the aft part of the engine block, I am guessing a bonding strap, but it is not connected to anything. Where should this be attached? Also, there is a grounding wire (pretty heavy gauge) connected to that engine that runs to a block with other grounding wires and then up to the electric panel. That wire is fried, almost the entire length. It actually melted some wires it was touching. What would have caused this? The binding strap not being connected? I don't have good access behind the panel to see where it terminates. Any ideas where it terminates so I can replace it? Thanks in advance.
Marc
 
I would not just replace a fried wire, something is wrong with the connection. I took Tom's advise and agree that a ABYC certified electrician is needed for our aging boats. I have one coming to square away the grounding issues and addressing the AC. I am not qualified to assure the two systems are correct to code so to speak.

Tom, I thank you for the referral to David Mogar. David had me purchase two BlueSea ELCI panels from WM and two Smart Plugs conversion kit combos and new wire for the AC. He is coming this Saturday along with his son to install these items and to assess the AC AND DC. While there he is going to bond my thru hull located next to the engine and others IF they are needed to be bonded. But the AC is his biggest concern. The ELCI panels are a marine version of a home GFI. It should keep stray electricity from a short or fault from a serious shock to someone in the boat or someone in the water while on shore power. As to DC, the main concern is corrosion and of course heating up a line and starting a fire. He is going to ck that out as well. I am installing a new air conditioner and he will be making sure all is well with that connection. Electricity in a boat is unnatural so I have an overkill with panel breakers and in line fuses on my DC side. (We'll see once David confirms all is well there). And with AC, primarily is a concern there is injury if not done right.

I will try to take pictures of what he did if that may help others.
 
The DC system on the boat is a wire from the starter( engine) to the (-) terminal of the battery, From there it should go to some sort of distribution bus bar to which all other neg wires are connected.
 
Marc
The copper strap may have been part of a bonding system for lightening protection or part of a counterpoise for an SSB radio installation. In either case that system appears to have been removed or forgotten. In which case the strap could or should be removed.
The Other wire that runs to a ground buss and has been fried is another thing. This is saying that there is something seriously wrong with your 12V or 110V systems. Before you begin to replace that wire you MUST find out the cause of the high amperage flow that has caused the damage. There are many things that could cause it. John Gonzalez is correct in saying that you might be needing a qualified ABYC electrician to go over your systems. The first thing to look for is a loose or corroded end fitting on any or all your connections. Such a connection will cause a very high resistance which will in turn cause a very high flow of amps. That loose connection could be on the Starter to "--" battery terminal, as Jose explains, which could cause the smaller gauge engine ground wire to overheat.

Jim
 
Tom, David Mogar is MIA!. I am asking because you may know if he is ill or something else is going on. Can't get a response from him about the electrical work that he was going to do. I have ELCI panels, smart plugs combos kits and expensive wiring for the AC and other things he was going to install plus ck out my ground on the DC side and bonding recommendations, but I haven't heard from David. Hope all is well with him.
 
I received a text from him yesterday. He is in New Jersey working on his power boat.
I will let him know you are trying to get in touch with him. I’m surprised he isn’t answering.
 
Thanks Tom for cking. I have studied a lot of literature in boat wiring and what is available on the Web of what David wanted to do and feel that he has good advice for the Morgan. So I will await his call. thanks for taking time on this.
 
I sent him a text but he hasn’t replied. I know he and Crystal went to NJ to visit her family for Easter. He sent some pics of his power boat up there that he is replacing the engines. I suppose he’s pretty wrapped up in his own projects and will respond soon.
Let me know if you need me to keep trying.
 
Thanks Tom, I left a few more than necessary messages and texts that soon he will begin to wonder if I am stalking him. So I will let him contact me. I have however studied literature from the ABYC code along with my boat books about boat wiring and am beginning to understand the AC and DC systems somewhat. For those reading this thread, pls understanding that this is coming from an novice, but I do strongly recommend that all boats having shore power connections, have an ELCI panel 8100 from Blue Seas for shock protection on and off the boat. Blue Seas has on their website, a DYI installation guide so you can connect this device on your on although they recommend if you have any doubts to have a ABYC certified electrician install it. It is to guard against overload and electrical equipment leakage and interrupt like a home GFCI, to open the circuit in case of over heating or AC leakage from a fault. I did find a ABYC electrician local to my area that has agreed to ck out my connections of this panel for each shore power connections and to ck over all other wiring. But if David can call me, that would be great for him to do this as he was the one that insisted that I have this device on each shore power line coming into the boat. Keep you posted Tom.
 
John,
I received this from David:

“I've been dealing with some tough family issues, excuse the communication delay”

I suppose you will hear from him soon.
 
Tom, thank you for relaying this information on to me. Hated that I got you in the middle. Hopefully he will give me a call. Like to still get him to ck out what has been done so far. thanks again.
 
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