What I really meant to say ...

[Jayman]

It dawned on me while reading another book on boat wiring that I may have misdirected everyone by my use of "a/c" for "AC".  In other words, apparently, everyone refers to air conditioning as a/c and AC is used for alternating current.  Soooo, my question had to do with the alternating current grounding buss for Pearsons.  If this helps you better answer the original question below, I'd appreciate any feedback you may have.
Thanks again and sorry for the confusion,
Jayman

"Recently, I bought my friend's 1978 Pearson, which he owned since 1980.  I have only been on it 2 times to work on, so am just getting acquainted with the systems.
I have read the posts regarding re-wiring and have yet to find the information locating the ground buss for the a/c system.  Can anyone tell me where it is located?  In addition, I have read the chatter about wiring diagrams and haven't been able to find any other than those located in the owner's manual.  If you any of you can point me in the right direction in terms of where I might find a more complete one, I'd appreciate it.
Thank you,
Jayman"

[slokat]

I'm not sure there is a bus for the AC grounds.  Next time I'm at the boat I'll look.

There are only (3) AC circuits on Windtamer (and an unused spare) and those grounds are tied together at the panel.

Plus the AC grounds should not be tied to any other item on the boat, other than the outlets and the shore power connection..

[barrylab]

On Relentless, there is a plywood cover over the forward bulkhead of the port side cockpit locker. Once removed it allows access to the AC distribution binding post arrays. The ground distribution is (of course) one of three binding post arrays.

[Jayman]

Thank you for the informative replies.  This helps, especially since we are snowed in and I'm 150 miles from my boat.  Where do you all attach the green (grounding) wire for your AC, to your engine, to an exterior grounding plate?

Thanks again,
Jayman

[kevin barber]

You will need to find the neutral ground bus.  What are you wiring?

[slokat]

Where do you all attach the green (grounding) wire for your AC, to your engine, to an exterior grounding plate?

If you connect the AC ground to your engine, and it ever is a part of a shorted circuit that bleeds power, you will probably either eat up your prop, or electrocute the diver that comes to scrape the bottom of your boat...

Do Not under any circumstances ground the AC power to any part of your boat!!!!

It should be connected to shore (through your shore power connection) so that it grounds there & connected at your AC outlets so that it travels to shore if shorted.

This is a Hard Fast Rule, don't break it!!!

[Jayman]

You will need to find the neutral ground bus.  What are you wiring?

I am wiring a new AC control panel.  My 365 only has a shore power connection that distributes AC directly to the hot water heater, the battery charger and 2 AC outlets.  From my reading of both Calder and Don Casey, I understand that there is a Neutral wire (white) that completes the circuit with the hot wire and then a ground wire (green) that must be connected to part of the boat that goes to ground.  I understand that carelessness with this step can either create galvanic corrosion problems or possible stray current problems for those near your boat in the water.  It is for that reason that I am being extra cautious.  Although I have rewired my home, boats are another story. 

It is my understanding when you attach a device to your panel you connect the black (hot) wire to positive, the white wire (neutral) completes the circuit and the green wire (ground) goes to a "grounding bus".  On the wiring diagram for the Pearon 365, the diagram leads the green wire to "the ground bus".  Both Calder and Casey refer to this ground as located somewhere on the boat.  This ground bus is what I'm looking for.  I also realize that you either fight with galvanic corrosion or possible stray current if there is any crossing of your neutral and ground wires.  Thanks for all the input. 

[Dale Tanski]

Maybe I can help.
The term "buss" maybe the issue here.  Any time mutable wires are connected to a common point it could be referred to as a Buss.  Perhaps you have heard the term Buss Bar.  In this case, the wires are terminated to a metal bar.  The bar is the common connection point that simplifies multiple connection process and that bar is often referred to as a Buss Bar. 

Because all of the neutral (white) wires in a typical AC circuit are connected together at a common location, that location or connection device would be known as the neutral buss.  Typically the buss is a strip of mental with multiple holes with capture screws to secure the wires to.  You probably have seen this in your home electrical distribution panel (Breaker or fuse box).  At the end of the metal buss bar there is a larger lug connection that the main neutral wire is attached that leads to the utility company, or in the case of a sub panel back to the main panel and so forth.  All of the individual circuits neutral wires connect to that neutral buss bar. 

The same thing is true with the AC ground part of the circuit.  Each circuit would have a ground wire. The ground wire is the unshielded (uninsulated) copper wire.  All of the grounds would be connected to a buss bar and this buss would be known as the ground buss.  It is the same physical arrangement, a metal bar with holes and screws to connect the ground wires to the buss bar.  At the end is a large lug that the main system ground is connected to.

The ground bus is physically (electrically) connected (bonded) to the distribution box which removes any potential (stray) electricity from energizing the box.  In some municipalities the neutral buss is also bonded to the distribution box.  In that case the ground and the neutral are one in the same in the dwelling.  In other areas of the country the neutral is kept separate from the ground until it gets to the utility pole where they are then bonded together.  If you followed this that means that the neutral wire (white) and the ground wire (uninsulated) are one in the same.  If you took and placed a meter (or load) from the hot wire (black) to the neutral it would complete the circuit your meter would show somewhere between 115 and 120 VAC.  The same thing would be true if you placed your meter between the hot and the ground, 115 to 120 VAC.  That is because electrically there is no or not suppose to be any potential difference between ground and neutral.

The flow of current (amperage) is the differential between a high potential and a low potential.  In this case the high is 120 VAC over the low which is ground or zero. Some of you are already asking why the duplication with neutral and ground? The reason for the two separate "grounds" is that you could have a potential of 220 VAC on one leg (black wire) and the second leg could have a potential of 100 VAC (white wire).  The differential of course is 120VAC just like in the example above however the potential to ground (zero potential) between the white is also 120 VAC and to the black is 220 VAC.  So... you might ask?  The hedge clipper you plug in sees 120 VAC and runs just fine however when you have one hand on the non-insulated metal handle and you kneel down to trim the low branches there is a potential of 100 volts plus between the lowest leg and the REAL ground and you become the ground wire. 
As a side note, your house has two "hot" legs coming into it, with 3 or 4 wires total.  Each hot leg is 120 VAC.  They are each BLACK and every other breaker in you distribution box is tied to every other hot leg.  The reason for this arrangement is to have balanced current flow between each hot leg so the panel designers play the one for you one for me game.  The third wire is WHITE and is the neutral. If you have a 4th wire from your utility company it is the ground.  I say "if" you have a forth wire from the utility because everybody has four wires however some areas of the country do not carry the ground into the dwelling (costs money) and rely on a ground rod that is pounded into the ground just outside your metering device.  Even if the utility supplies the GROUND leg you still will have a ground rod just to be sure.  The two hot legs coming in give you 120 VAC to neutral, and 230 to 240 VAC between the two of them.  So... as 220 VAC device is connected to the two hot legs and a 120 VAC device is connected to one hot leg and the neutral.  Perhaps you have seen a red wire in you breaker box.  They designate the 2nd hot leg in red once it is in the house

These two hot leg systems in our houses are known as a single phase system.  In reality and over in Europe it is known as a two phase system because of the two hot legs.  Don't mention this to your typical house electrician as it will only confuse them.  Industrial applications often use three phase systems (3 hot legs). 

OK, back to the question...  On a boat all of your hot legs (black) go out to your individual devices.  In your case a few receptacles, a 120VAC (single phase) water heater and your battery charger.  The black leg is always protected because it is the only leg that has any electrical potential. Protection here means Circuit breaker of fuse.  It has to be protected right up front before it travels through you boat (or home) in case it somehow becomes uninsullated and can physically come in contact with the lower potential neutral  (White)or ground (green).  The return leg or neutral (white) all come back and hook together to the neutral buss.  The same is true with the ground leg (Green), they connect to the ground buss.  Here is where the difference is.  The ground buss and the neutral buss are not connected together on the boat.  They are individually fed to and from the boat via the shore power cord and the connection to ground is made ashore.  There also is no ground (water?) rod on the boat because water has a resistance to it.  If there was electrical leakage (faulty device) in you AC system on the boat and it was grounded to the water, a current flow would be created because of the resistance in the surrounding water or the potential difference to the bottom (real earth ground).  Remember potential is the important item here (remember the example way above).  The hull fitting that was the ground rod would pass the potential to the water and be eaten away by a chemical reaction known as electrolysis.  Same electrolysis that eats your zincs away on your prop shaft and heat exchangers.  In that case the differential is only 12 volts, however it would be 10 times worse with a 120 volt potential difference.

So... let's wrap this up.  NEVER tie the ground side of you AC electrical to the ground side of you DC electrical.  The AC ground must also be kept separate from the AC neutral conductors.  That connection will be handled shore side.  Also, never mix (connect) the ground of an AC system with the ground of a DC system. 
DC electrical systems typically use the item to be powered as the return (low potential) leg.  Your car is a great example.  It uses a DC system and the entire chassis and engine is the return leg or ground.  The negative (ground) side of the battery is connected right to the chassis.  That is why the radio for example only as a HOT wire attachment.  The metal chassis of the radio connects to the metal car chassis and completes the circuit.  On a boat they try to minimize having the item as the ground leg however it can't be helped.
Because of the potential of a lightning strike, boat builders ground the mast to a thru hull fitting or ground plate.  They do the same with the rigging, bow and stern rails, steering pedestal or anything of size because they do not know where the lightning will strike.  They direct the lighting (very high potential) off of the boat over the side to a lower potential (water). 
Your engine on your boat is grounded and only a hot wire (red) goes to the starter.  The prop shaft is also a ground to the water that is why it has zinc.  If there is even the slightest difference in electrical potential between the negative battery terminal and the water the zinc will dissolve through electrolysis and save your shaft.

By the way.  AC systems use WHITE and BLACK, the black being the high potential conductor.   DC system use BLACK and RED with the red conductor being the high potential carrier.  See a problem here?  Besides being backwards to each other, if you stumble across an individual wire on your boat in the bundle  and it is BLACK, is it a harmless DC ground or a hot AC leg?   That is why the boating industry has recently adopted YELLOW and RED for DC systems with the Yellow being DC ground.  They also color the cover jacket in BLUE for this new wiring so all white jackets are AC and blue jackets are DC.  I would recommend this method when running new wiring on your boat.
Hope this made some sense and of course helped.  If not, send me a specific question and I will see what I can do.

Good Sailing...   Dale Tanski

[Jayman]

Perhaps I'm confused by my reading of the wiring diagram in the Pearson 365's wiring diagram (# Tp-46A).  What it illustrates is the 3 AC wires coming in through the shore power inlet cord, fused by (2) 15A fuses on the black and white wires.  The white wire goes to the "neutral buss" and the green wire is pointed to "the ship's ground buss".  That is the point that I am looking for.  When you say that the green (ground) wire is grounded through shore power it would seem then that the diagram should then point the green (ground) wire back to the shore power cord. 

I know I'm missing something.  Perhaps if I was looking at the wiring currently on my boat, I could trace the path of the green wire, say after the hot water heater; to where it ultimately connects.  But, I'm not anywhere near my boat, so I'm looking for some guidance or pictures or dialog (like we're having) in order to answer this mystery.  This is my best attempt at making my question as clear and specific as I can. 

Thank you all for taking the time to educate me,
John Manzano

[Dale Tanski]

John,

The shore power does consist of a
BLACK - Hot, 120 VAC
WHITE - Neutral
GREEN - Ground.

You are correct that the ground off of the shore power plug (green) should go to the AC ground bus.  You are also correct that if you trace back another 120 VAC circuit it should lead you to the 120 AC GROUND BUS.

This however is as far as I can get you on your boat because when I purchased Maruska, the aft main bulkhead was basically missing along with the battery platforms, galley cabinetry and the engine cover box.  I know from pictures of other P365's that I have seen, that there was a great deal of electrical attached to the aft side of the main bulkhead in and around the battery selector switch port side.  I suspect that the AC power system was probably located on the starboard side as that is where the shore plug, hot water heater and my battery charger was located.

Dale

[Jayman]

Again, thank you all for your help.  It seems like I am left with no choice however, but to re-visit my boat and check the ground wires to a common point.
Jayman

[barrylab]

I'll be working on Relentless today. I'll take some pictures, and post them.

[Jayman]

That will be terrific!  I look forward to seeing them.
John

[barrylab]

Here's a couple of pictures looking forward in the port side cockpit locker, with the panel removed. The wire mess is the result of a previous owner, and will require a fair amount of cleanup. The Buss bars are clearer in the second photo.

-Barry

[Jayman]

Barry,
Thank you for the pictures.  I had the opportunity to visit my boat and saw the same arrangement you have in your port cockpit locker.  Are all of your AC wires found in that port locker?  

I also found a rather sizable array of wires in the starboard cockpit locker forward of my hot water heater.  Do you have the same arrangement?  Bundled together were my DC wires along with the AC wires.  In addition, there was a breaker for the AC secured to the starboard locker bulkhead.  

I have attached a couple of pictures from my starboard cockpit locker showing the additional configuration that I have there.  YOu may notice that someone installed a 60 amp breaker on my 30 amp AC system.  I will change this out.  But any suggestions that you all my have about how the AC system is configured will be appreciated.