Having disconnected and labeled all the 12 V wiring, the 110 AC is
now visable. It appears that all the AC ground wires (green) are run
to a common buss. But , then, the AC Ground buss is connected with
a 6 ga. wire to the DC negative buss. This doesn't seem right to me.
Is it?

Marc, unless you're in mid-ocean at the moment, I think now is the time
to purchase a book on marine electrical wiring. Read through it and then
post any questions that remain. Be glad to help.

Good luck.

Chuck




Marc wrote:
Having disconnected and labeled all the 12 V wiring, the 110 AC is
now visable. It appears that all the AC ground wires (green) are run
to a common buss. But , then, the AC Ground buss is connected with
a 6 ga. wire to the DC negative buss. This doesn't seem right to me.
Is it?

Marc wrote in news:ufm1p1h2l7qr8s8vs3vbso6j1so1l3apgr@
4ax.com:

Having disconnected and labeled all the 12 V wiring, the 110 AC is
now visable. It appears that all the AC ground wires (green) are run
to a common buss. But , then, the AC Ground buss is connected with
a 6 ga. wire to the DC negative buss. This doesn't seem right to me.
Is it?

They do this to insure your engine, underwater propulsion gear and
everything hooked to the DC ground system is connected to every other
stupid boat and the marina's big earth ground system, making one HUGE
battery out of those zincs you can't figure out why they disappear so
fast.

There's absolutely NO reason why the independent DC system should be
connected to the AC ground bus I know of. Ours isn't. I'll be damned if
I'd pay with MY zincs to protect your prop because my zincs are hooked
through the AC wiring ground to your zincs.....

Oh, hooked up like that, too, your zincs are protecting the whole
electrical system of HIS marina any place it touches the water or makes
contact with the earth.

Aren't you being, inadvertently, nice....(c;

So are you complaining that the AC ground and DC negative are both connected
to the boats ground or where they're connected?


"Larry" wrote in message
...
Marc wrote in news:ufm1p1h2l7qr8s8vs3vbso6j1so1l3apgr@
4ax.com:

Having disconnected and labeled all the 12 V wiring, the 110 AC is
now visable. It appears that all the AC ground wires (green) are run
to a common buss. But , then, the AC Ground buss is connected with
a 6 ga. wire to the DC negative buss. This doesn't seem right to me.
Is it?

They do this to insure your engine, underwater propulsion gear and
everything hooked to the DC ground system is connected to every other
stupid boat and the marina's big earth ground system, making one HUGE
battery out of those zincs you can't figure out why they disappear so
fast.

There's absolutely NO reason why the independent DC system should be
connected to the AC ground bus I know of. Ours isn't. I'll be damned if
I'd pay with MY zincs to protect your prop because my zincs are hooked
through the AC wiring ground to your zincs.....

Oh, hooked up like that, too, your zincs are protecting the whole
electrical system of HIS marina any place it touches the water or makes
contact with the earth.

Aren't you being, inadvertently, nice....(c;

Larry, it is quite difficult to prevent your "independent" DC system
from being connected to the AC ground bus. Like it or not, it is
probably connected through the water, providing an opportunity for a
potential difference between your DC ground system and the grounded case
of an AC appliance. An improperly wired boat in the next slip can cause
real safety problems aboard you vessel.

You can safely isolate your system from the galvanic couples you fear
with an isolation transformer or a galvanic isolator. I know you are
well aware of both. You can also isolate your underwater metal (prop,
shaft, etc.) from both the AC and DC ground systems, which may be what
you meant to suggest.

Chuck


Larry wrote:
Marc wrote in news:ufm1p1h2l7qr8s8vs3vbso6j1so1l3apgr@
4ax.com:


Having disconnected and labeled all the 12 V wiring, the 110 AC is
now visable. It appears that all the AC ground wires (green) are run
to a common buss. But , then, the AC Ground buss is connected with
a 6 ga. wire to the DC negative buss. This doesn't seem right to me.
Is it?


They do this to insure your engine, underwater propulsion gear and
everything hooked to the DC ground system is connected to every other
stupid boat and the marina's big earth ground system, making one HUGE
battery out of those zincs you can't figure out why they disappear so
fast.

There's absolutely NO reason why the independent DC system should be
connected to the AC ground bus I know of. Ours isn't. I'll be damned if
I'd pay with MY zincs to protect your prop because my zincs are hooked
through the AC wiring ground to your zincs.....

Oh, hooked up like that, too, your zincs are protecting the whole
electrical system of HIS marina any place it touches the water or makes
contact with the earth.

Aren't you being, inadvertently, nice....(c;

"johnhh" wrote in
:

So are you complaining that the AC ground and DC negative are both
connected to the boats ground
"Boats ground"? What's that? The boat is made of PLASTIC, an insulator.
It has no "ground". It has a negative battery bus. It has an AC supply
ground connected to the shore power ground system. What's the "boats
ground"?

I hear this a lot. It doesn't exist. The battery negative bus has no
relationship, whatsoever, to the AC shore power ground as the two systems
are totally isolated from each other unless there is something wrong with
your battery charger, dual-voltage fridge or other AC/DC components.

Touching the AC shore grounded appliance, already hooked to AC shore
ground, with one hand and touching the engine block connected to the sea
and DC ground bus results in no hazard...unless the AC shore ground is
defective PLUS the appliance or device is defective. Touching an AC
grounded device with one hand and a defective 2-wire toaster with the hot
lead of the AC line hooked to its metal case has the SAME SHOCK as
touching the DC ground bus hooked to the engine block....unless, of
course, the boat has a proper GFI that should, but is not, required
aboard the boat....just like proper NEC-approved breaker panels are not.
(A bunch of little plastic breakers on a plastic panel screwed into a
flammable wooden box made of some exotic, expensive wood is NOT up to the
National Electric Code of the USA or any country with any brains. AC and
DC panels in boats are made that way to SAVE MANUFACTURERS MONEY. They
are NOT "safe", from fire (flammable) or explosion (not sealed against
fumes) at all!

Ok, back to the buses connected together for some stupid reason.....

If the DC bus hooked to the zincs by virtue of the DC bus being connected
to the engine block....is connected directly to the AC bus ground back to
shore power ground through the boat's impressive yellow shore cable, this
connects the boat's zincs STRAIGHT TO THE BOTTOM OF THE HARBOR...not to
mention every other boat wired this stupid way. YOUR zincs are hooked to
HIS underwater metal parts through the common-connected AC shore power
ground wires.

So? What happens now?........(you ask).....

Ever notice the metal conduit hanging loose under every dock on every
marina in the country? See how it hangs into the water? If I hook MY
zincs to that metal conduit (by the AC shore power ground wire from the
boat with the DC negative bus hooked to AC shore power ground), MY zinc
will fizz away protecting the rotting plating on that sagging conduit,
every little ground wire touching anything conductive hooked to the
water, and even the ground rod back at the feed point from the power
company! Isn't that nice of me?

Is it any wonder some people are going through those amazingly-expensive
zincs at an alarming rate in your marina? Zincs protect what they are
CONNECTED to. They are a virual shorted battery, the zinc one plate, any
metal part making connections with the water the other plate and seawater
as the electrolyte. In order for the battery to DISCHARGE, eating the
zinc, it has to have a DIRECT DC PATH from the zinc to that plate.
Unhook the path, you've opened the shorted battery circuit. The only
battery plate the UNHOOKED boat makes a battery with is the metal part
the zinc is mounted on and is protecting, not every neighboring boat
connected to the AC power shore ground.

Every AC device in the boat, with, of course, the exception of insulated,
UL-approved, appliances-electronics-doubleinsulated drills-etc....should
be hooked for safety to the SHORE GROUND, to prevent the AC line from
appearing on the metal cabinet parts of it. Of course, it would be nice
if the damned AC panel, ITSELF, on pleasure boats were so connected.
They're not. Look into the wooden box. Metal breaker panel hooked to
green wire? Not most.

If you disconnect the DC negative bus from the AC Shore Ground green
wire, you measure the DC potential caused by the zincs...the
electroplating voltage trying to destroy the zincs. It CAN'T have any AC
voltage between the Shore Ground hooked to a ground rod somewhere and the
DC ground bus hooked to the engine block....doesn't wash.

chuck wrote in news:haikf.8489$N45.4470
@newsread1.news.atl.earthlink.net:

providing an opportunity for a
potential difference between your DC ground system and the grounded
case
of an AC appliance. An improperly wired boat in the next slip can cause
real safety problems aboard you vessel.


Show me how. The water is earth ground, no matter how the joker's boat
is wired next door. If he's wired wrong, the AC current through the
water will trip the AC breaker on the dock. Try it.

There is NO WAY for the guy's boat next door to raise the AC potential of
the whole ocean up off the AC shore ground potential my fridge is
connected to! He'd need a thousand amp breaker to raise it a tiny
fraction. The shore power ground is hooked to the earth/seawater.

chuck wrote in news:haikf.8489$N45.4470
@newsread1.news.atl.earthlink.net:

You can also isolate your underwater metal (prop,
shaft, etc.) from both the AC and DC ground systems, which may be what
you meant to suggest.


No, I mean to completely separate the DC negative bus/engine block from the
AC line Shore Ground bus....

There is no reason whatsoever for them to be connected together. The
transformer in the battery charger isolates them. The case of the battery
charger should be connected to the AC shore ground ONLY if it's made of
metal, which it no longer is any more. The metal case, if it has one, of
the AC/DC fridge should be connected to shore ground but NOT the battery
negative bus, either....

Shhhh....don't tell anyone.....Lionheart's HOUSE batteries are NOT
connected in any way to the STARTING battery's negative ground bus UNLESS
you reach under the aft cabin bunk and throw the grounding switch to
ON....allowing you to connect the house batteries to the engine for
emergency starting or charging the house batteries off the starting
battery's alternator in another emergency. Our house battery alternator is
connected to the house battery negative bus....NOT engine ground because
it's mounted to the boat on a separate bracket and uses a rubber belt.
Zincs last YEARS, not months. Nothing on the house circuit connects to
underwater that needs a zinc. There are no leakage paths....with even
separate DC negative busses.

Works great....(c;

(big snip)
There's absolutely NO reason why the independent DC system should be
connected to the AC ground bus I know of. Ours isn't.

One guy we know had a bozo miswire his shore cord, and while lying
along side his engine, grabbed hold of an AC grounded appliance frame. A
hearse was needed to transport him to the next event in his life.
Many of you have seen this waiting to happen, and maybe turned a little
skin into smoke.
Electricity is not foolproof! Eat your zincs out!

Lynn....... see these scars?

Larry wrote:
chuck wrote in news:haikf.8489$N45.4470
@newsread1.news.atl.earthlink.net:


providing an opportunity for a
potential difference between your DC ground system and the grounded

case

of an AC appliance. An improperly wired boat in the next slip can cause
real safety problems aboard you vessel.



Show me how. The water is earth ground, no matter how the joker's boat
is wired next door. If he's wired wrong, the AC current through the
water will trip the AC breaker on the dock. Try it.


Well, the classic example of this is when the guy on the boat next to
yours uses a 2-wire AC cord on an automotive-type battery charger. The
charger develops leakage between the hot AC wire and the 12 volt DC
ground. Won't trip any breakers because the current is too small. The
circuit could easily deliver 10 amps forever with nothing tripping.
Remember that the breakers are sized to trip before the wire causes a
fire; NOT before enough current has passed through a person to cause
electrocution. We're not talking about someone savy enough to use GFCI
outlets here which can detect small current leakages.

Alternatively, an automotive-type charger is plugged into a makeshift
extension cord with the hot and neutral wires swapped. No green wire at
all. Even without a leakage or short, the hot AC wire is now connected
directly to the neighbor's DC ground system to his propeller. Again,
nothing trips because the path through the water to the AC system's
ground/neutral junction is too high a resistance to carry 15 amps (or
whatever the breaker is rated at) with 120 volts applied.

Next, you grab your engine with one hand and open the door of your
fridge with the other as you reach for a cold one and you receive an
unhealthy dose of 60 Hz.


There is NO WAY for the guy's boat next door to raise the AC potential of
the whole ocean up off the AC shore ground potential my fridge is
connected to! He'd need a thousand amp breaker to raise it a tiny
fraction. The shore power ground is hooked to the earth/seawater.


What happens, Larry, is that your fridge cabinet is connected to the
green equipment grounding conductor and to an AC ground/neutral junction
on land. Your engine is connected through the water to the hot AC wire
on the neighboring boat. The voltage between those two pieces of metal
could approach 120 volts. Even a zinc/copper galvanic couple will result
in a measurable potential difference in seawater. No need for massive
currents and no need to think in terms of raising the potential of the
whole ocean. :-)

Draw out the circut and it will pop right out at you.

There are documented cases of swimmers and boaters suffering
electrocution from these problems. How probable? Different subject.
First let's establish how it could happen.

Chuck