[QUOTE=smessick;14966]While installing a new battery charger which has a case ground, I came across a requirement that the DC negative buss is to be connected to the AC ground buss. A little online searching showed that this is a ABYC requirement and is intended to prevent a short from AC to DC from leaking current into the water around the boat.

My 1986 C36 is not wired this way, and apparently their are differing opinions. What are the thoughts on the forum, and does anyone know if later Catalinas have these busses connected?[/QUOTE]

Our 86 C-36 (could have been an 85 sold as 86) was wired per ABYC standards. Along the way someone may have added the AC/DC ground tie on our boat. Many unknowing DIY's and even some hack marine service guys will remove this but few add it.

This requirement is there for HUMAN SAFETY and should be there and I don't know an expert in the industry that disagrees with it. AC white/neutral and AC/green ground should NEVER be tied together on-board unless at a "source" of power such as a gen set, inverter or IT....

Main Sail, I am not clear on what you just wrote. Aren't there are three wires carrying AC to the boat: a black (hot), a white (neutral), and a green (ground)? What I am hearing is that (except for terminating at a power source) the white and green should NOT be connected together.

In other words, the 120VAC is conveyed between (or 'across'...what's the right preposition to use here?) the black and white wires. The white never ties to the boat's DC ground, but the green wire does tie to the boat's DC ground. Have I got that correct???

(Sorry for the confusion.)

[QUOTE=LCBrandt;14970]The white never ties to the boat's DC ground, but the green wire does tie to the boat's DC ground. Have I got that correct???

(Sorry for the confusion.)[/QUOTE]

Yes, the only place white and green are ever tied together are on shore, a gen set or inverter.

Green ties to ships DC ground...

Many builders put the AC/DC ground tie where you can't see it. The easiest test to to put set a DVM to check for continuity with the audible tone. Next just touch one lead to the AC green ground bus and the other to any DC ground on-board. No tone, no tie..

I tested for this ground connenction over the weekend and also found it not to exist. The wiring on my boat appears to be mostly original with few signs of modifications other than added instruments, battery monitor, and a overhead galley light. This leads me to believe that it was never made at the factory.

My question then is: Is there an optimal place to make this connection? The most convenient appears to be at the back of the panel where the AC ground (green) buss is in close proximity to the DC ground (Black) buss. A #12 wire jumper??

Gary, are you positive (pi!) that there is not already a jumper on the isolated terminal blocks? sometimes they get kinda "hidden" under the screws.

[QUOTE=Gsmith;15008]I tested for this ground connenction over the weekend and also found it not to exist. The wiring on my boat appears to be mostly original with few signs of modifications other than added instruments, battery monitor, and a overhead galley light. This leads me to believe that it was never made at the factory.

My question then is: Is there an optimal place to make this connection? The most convenient appears to be at the back of the panel where the AC ground (green) buss is in close proximity to the DC ground (Black) buss. A #12 wire jumper??[/QUOTE]

Yes you can simply make it behind the DC panel my making a 10GA gree jumper and wiring it between the reen AC bus and the DC ground bus.

I don't know when Catalina began doing this. Cape Dory for example did it back into the mid 70s' but I've noticed enough Catalina's without it, at least into the early 90's, to wonder if it was done from the factory or not on the earlier boats. Ours had it, IIRC tied to the engine, but it may have been added. On some boats they went from near the AC inlet to the engine with a green wire and on others they used a jumper between DC & AC behind the panel.

Thanks maine sail #10 it is then. Stu, with the proximity of the buss bars I would have thought that would be the logical way for the factory to make the connection but audible continuity testing from several locations proved otherwise.

Hi, everyone.

Per my reading of both Nigel Calder "Boatowner's Mechanical and Electrical Manual" and Everett Collier's "The Boatowner's Guide To Corrosion" (which Calder highly recommends), the ONLY solution to both the safety problem and the stray current problem is an isolation transformer.

A galvanic isolator, while ok, is just not a great solution..and a great galvanic isolator (ABYC approved) costs almost as much as a decent isolation transformer, according to Calder.

This is now on my shopping list.

[QUOTE=benethridge;15379]Hi, everyone.

Per my reading of both Nigel Calder "Boatowner's Mechanical and Electrical Manual" and Everett Collier's "The Boatowner's Guide To Corrosion" (which Calder highly recommends), the ONLY solution to both the safety problem and the stray current problem is an isolation transformer.

A galvanic isolator, while ok, is just not a great solution..and a great galvanic isolator (ABYC approved) costs almost as much as a decent isolation transformer, according to Calder.

This is now on my shopping list.[/QUOTE]

Isolation transformers are the best bet but a GI is better than nothing. The reality is that boats often suffer from corrosion caused by their own on-board problems then they do from external problems.. If marina's were the only issue I would not deal with corrosion issues on mooring sailed boats, but I do, at a rate that nearly equals marina sailed boats. DC corrosion is far more harmful than AC corrosion..

Ok I checked our boat out and there is no tie between the DC ground and the Green AC ground. Via a ohm meter. The last 2 years now when we have been on the hard here at Green Cove Springs and I try to plug our shore power cord into a outlet in the yard I have tripped the gfi on the marina outlet, If I take and undo the green in the panel all is fine. There is a older 36 just 2 boats from me and he is running a 16 gauge extension cord so he does not have the same issue as I have. I asked him as well about the AC to DC ground and he does not have it either. This is really the only time I have ever had a issue with it. What happens if I leave it the way it is? Just curious. If I do install the jumper will I see more issues with stray voltage if any? Just a few normal questions is all.

It can kill you.

This isn't just me saying this. It's in Nigel Calder's book with a good explanation.

The reason people disconnect the two is to avoid the stray current corrosion problem, but it's a potentially deadly solution.

You have two solutions:
1. a galvanic isolator, which isn't a great solution coz the thing can fail for several reasons, and in a bad way, bad meaning it can kill you. See Calder p 139 for why.

2. an isolation transformer. This is the only solution Calder and Collier (the two books on the subject I've read) recommend, since it is safe (fails in a safe way) and it solves the stray current corrosion problem. Unfortunately it's an expensive solution, so not many people do it. They just do (1) or take the risk.

Ok. So are the new boats being built with either the galvanic isolator installed or the an isolation transformer installed or nothing?

[QUOTE=Maine Sail;15387]Isolation transformers are the best bet but a GI is better than nothing. The reality is that boats often suffer from corrosion caused by their own on-board problems then they do from external problems.. If marina's were the only issue I would not deal with corrosion issues on mooring sailed boats, but I do, at a rate that nearly equals marina sailed boats. DC corrosion is far more harmful than AC corrosion..[/QUOTE]

Beats me, but I'll bet they are not, for the reason Maine Sail says above.

Per Maine Sail, I'm thinking maybe I'll just take the (hopefully) small marina risk of corrosion induced by my neighboring boats, and check my zincs more frequently for any signs of rapid corrosion. (If I'm sacrificing my zincs for all my neighbors' boats as well as mine, maybe I can get them to chip in on my zinc replacement cost. :-))

Tough problem.

[QUOTE=benethridge;15439]The reason people disconnect the two is to avoid the stray current corrosion problem, but it's a potentially deadly solution.

You have two solutions:
1. a galvanic isolator, which isn't a great solution coz the thing can fail for several reasons, and in a bad way, bad meaning it can kill you. See Calder p 139 for why.

2. an isolation transformer. This is the only solution Calder and Collier (the two books on the subject I've read) recommend, since it is safe (fails in a safe way) and it solves the stray current corrosion problem. Unfortunately it's an expensive solution, so not many people do it. They just do (1) or take the risk.[/QUOTE]

ben,

The new GI's, that meet ABYC standards, don't fail the same way they did when Nigel and Everett wrote those books. The new GI's are "fail safe" meaning if a diode pops you don't lose the AC ground... ProMariner, Guest Dairyland Electrical Industries (DEI) all offer reasonably priced fail safe GI's meeting the current ABYC standards...

True, and Calder mentions that in his book, but he also mentions that they are more expensive than before the new ABYC standard...and they still have their little idiosynchrasies.

Here is a good article that explains the problems of stray current and then, near the end, a discussion of the pros and cons of both galvanic isolators and isolation transformers:

[url]http://www.passagemaker.com/magazine/article-archives/item/1234-galvanic...

Given all this, I agree with you now. I'd go with the galvanic isolator. Looks pretty safe and it's about half the price of a decent marine isolating transformer. I can't even buy an isolating transformer from West Marine. That's how uncommon they are.

If someone knows of a good one at a reasonable price, I'm interested.

[QUOTE=benethridge;15449]True, and Calder mentions that in his book, but he also mentions that they are more expensive than before the new ABYC standard...and they still have their little idiosynchrasies.

Here is a good article that explains the problems of stray current and then, near the end, a discussion of the pros and cons of both galvanic isolators and isolation transformers:

[url]http://www.passagemaker.com/magazine/article-archives/item/1234-galvanic...

Given all this, I agree with you now. I'd go with the galvanic isolator. Looks pretty safe and it's about half the price of a decent marine isolating transformer. I can't even buy an isolating transformer from West Marine. That's how uncommon they are.

If someone knows of a good one at a reasonable price, I'm interested.[/QUOTE]

A good quality IT will cost you $$$$. The cheap ones are LOUD, bulky and heavy..

Steve D. is one of the best technical writers in the industry. He gets it and is one of the few experts I agree with nearly 100% of the time. You'd please if you registered for his blog.. Excellent stuff...

Ok so this grounding issue has me going now. Tonight I did and experiment while on the hard still. With the shore power cord plugged in to a GFI breaker on a post and my green A/C wire off the terminal strip. I then took a digital multi meter set on DC volts and ran one probe to the prop shaft and the other one stuck into the ground. The reading was 5.89 volts.

Next I took and hooked up a jumper wire from the green A/C wire to the D/C ground terminal strip. Then put the green wire back as is should be and checked the voltage in the same manner as before. I got .338 volts. I also checked it with out the jumper between the A/C and D/C with the green hooked up as it should be. I was getting the same .338 volts. Reason I have the green unhooked is it keeps tripping the GFI on the post. I hope someone with a little more electrical smarts can tell me what is going on other then a grounding issue

A couple of updates:

1. I took my boat out into the bay and snorkeled to check the zinc on the prop shaft. There was no zinc. Totally gone, and it was put on new 2 months ago! I called a reputable diver, who is going to replace it this week. He also recommended that I get a galvanic isolator. Apparently that is a problem around here, coz...

2. I was chatting with another Catalina 36 owner who lives a few boats down from me. He learned the hard (spelled $$$) way about galvanic corrosion. He says he now has a galvanic isolator on his boat.

I'm sold.

how if at all would that apply to boats in fresh water? I recently installed two 30 amp "smart plug" lines and planning to install a dual pole circuit break on both along with a single 50 amp GI but as going to wait till i moved the boat to the coast in the spring, should i be concerned at this point since i am in fresh water? seems to be a salt water condition but as far as i'm concerned it is all magic

I'm thinking it's a salt-water condition. My boat has been in fresh water for the last 25 years, with no zincs or magnesiums, and there wasn't a speck of corrosion.

As soon as I moved to salt water, the corrosion started almost immediately.

[QUOTE=mutualfun;15456]Ok so this grounding issue has me going now. Tonight I did and experiment while on the hard still. With the shore power cord plugged in to a GFI breaker on a post and my green A/C wire off the terminal strip. I then took a digital multi meter set on DC volts and ran one probe to the prop shaft and the other one stuck into the ground. The reading was 5.89 volts.

Next I took and hooked up a jumper wire from the green A/C wire to the D/C ground terminal strip. Then put the green wire back as is should be and checked the voltage in the same manner as before. I got .338 volts. I also checked it with out the jumper between the A/C and D/C with the green hooked up as it should be. I was getting the same .338 volts. Reason I have the green unhooked is it keeps tripping the GFI on the post. I hope someone with a little more electrical smarts can tell me what is going on other then a grounding issue[/QUOTE]

You MAY have an AC leak. You need however to measure for current in the green wire. Any current flowing in the green wire can cause a GFCI to trip. The white and black wires should be "balanced" if they become out of balance some current wants to flow through the green wire. Any current flowing through the green wire is BAD.

Very often this is caused by a bad or dirty connection, bad power cord etc. etc. but some appliances can also case these leaks. Start by isolating all loads then flipping them on one at a time while measuirng for current on the green wire. Most DVM's have a 10A scale and you can insert your meter into the green wire to measure current. If you have more than 10A on that wire and you pop the fuse in the meter so be it. because you should never have anywhere near 10A of current on the green wire, or any, for that matter.. Water heaters are NOTORIOUS leakers of AC.....

A GFCI will trip at 5mA or 0.005A and an ELCI or RCD will trip at 30mA or 0.03A. It does not take much of a current imbalance to trip a GFCI. If you are tripping the GFCI you very likely have a leak. Remember you want to measure for current on the green wire not necessarily voltage.

Thanks Main Sail for the idea. I took my digital clamp on amp meter and checked the green wire and I had just .032 of an amp in it, I am thinking it is the GFI's in the marina as a few other boats have had to do what I did or are running just a extension cord to their boat. I have never had a issue with corrosion due to current in the water. Yet. Maybe it is just luck.

I ordered a ProMariner ProSafe FS30 from West Marine. $300. Easy installation.

I had moved my shore plug to just above the electrical panel, so the ground wire run to the galvanic isolator is very short. See attached picture.

It needs to be in a cool, vented, dry place or they will void the warranty...so this was the best spot I could think of.

I'm looking at one of these:

[URL]http://bluesea.com/products/8100[/URL]

A local chandlery is carrying these and recommending them to comply with the ABYC E-11.11.1 requirement on all new boats.

"An Equipment Leakage Circuit Interrupter (ELCI) shall be installed with or in addition to the main shore power disconnect circuit breaker(s) or at the additional overcurrent protection as required by E–11.10.2.8.3 whichever is closer to the shore power connection."

The panel type are about $200 up here and one in a waterproof box is $320. Since it's designed exactly for this purpose would this not be the best route to go? Just not sure where it should be installed. Replace the main breaker at the panel or replace the breaker at the power inlet? If it is the latter, do I need two since we have two inlets, front and back, tied together with one breaker by the look of it.

I think I likely would get the #8101 which includes provisions for up to 5 branch circuits and replace the entire existing main breaker with this panel and run the existing 4 circuits out of it. Then add a 2nd 30 amp breaker at our front inlet, the rear one already has one on it.

Hey Bud,

With your forward and aft shore power connections, are they switched so the one not in use is dead or are they directly connected in parallel so they are both live if one is in use? I believe you will need a separate 30 amp breaker on each as they are both more than 10 feet from the panel.

Tom, that is the question. I don't know if the front inlet was factory or not, I don't think it was in which case I'm betting it's not going to have been done right. I bet they tied it into the back one somewhere to just use 1 breaker. I am figuring on adding another 30 amp breaker right at the front one. Going down to the boat next week and am going to measure the panel to see if this will fit, from pictures I have here I think it will and it will be a neat solution to several problems, if it works.

Some marinas down our way are getting really hinky about AC problems, they inspect transients power cords, etc. So time to try and get this sorted out properly.

Bud,
I'm pretty sure the bow inlet is not from the factory. I've never seen any Catalina come out of the factory with a 120V inlet in the bow.

Right. I'm going to go through the whole AC installation and see what's what with it. We've never had any problems with it but given the way most things were done on this boat it should be looked at.

Blue Sea also makes just the ELCI breaker itself. It's $145 with toggle switch and probably would need only another hole in the panel for the test button. That would be a pretty easy fix, if it's the appropriate thing.

When I ordered and bought my 1999 new the dealer offered a dealer option second bow power inlet. It has an A-B type of switch by the nav station. I almost never use the aft power inlet.