On 21 Apr 2004 18:44:14 -0700, (Parallax)
wrote:

"Rod McInnis" wrote in message ...
"geneb321" wrote in message
...
There is an excellent article on testing for grounding problems between
shore power and boat at: http://www.yandina.com/electrolysis.htm


I don't recommend following the instructions at that web site. Creating a
potential safety hazard so that you can eliminate galvanic corrosion is not
a good trade off in my book. You would also have to eliminate just about
every piece of 110 volt gear (TV, ice maker, battery charger, etc.) or come
up with elaborate ways of isolating them.

Rod

I suggest that somebody develop an induction system similarto that
that was to be used with electric cars. No direct electrical
connection to the boat so we eliminate thjis problem.

There is such an induction system - called an "isolation transformer"
This provides the basis for an effective safety system.
Appreciable power ratings cost.

A poor man's approach, which unfortunately has limited power
capability is to join two similar mains transformers at their
secondary windings. The thoughput is then limited to the power
capability of one such secondary.
Example: take two step down transformers rated 120 / 24 volts 10 amps

Connect the 24 volt windings together.
Result, an isolated mains output limited to 240 watts ( = 24V X 10 A)

Brian W

Here's one scenario.
The shore power distribution hardware carries a live 115 volt AC line,
a neutral line and a ground line.

As likely as not, the ground line is connected physically to the
neutral line at some closeby point. (For ALL slips)

Or if not, some misguided owner may connect his neutral lead to ground
return, with much the same effect.

This notional ground may have several volts imposed on it by the
voltage drop in the neutral return.
If you carry the ground on board to a through hull, this potential can
drive a current to the ACTUAL ground (below the water)

Brian W

On 21 Apr 2004 16:49:29 -0700, (Chuck Baier)
wrote:

Thanks for the input from everyone. One thing that is puzzling here.
Each slip is a separate home run to a meter. None of the slips are
interconnected. Each is independent. If this is the case leakage from
other bots on the ground shouldn't affect my zincs. We are looking for
a source that is outside the AC connections. At least that is what I
beleive.


"geneb321" wrote in message ...
There is an excellent article on testing for grounding problems between
shore power and boat at: http://www.yandina.com/electrolysis.htm
Gene
SV Sea Gypsy

"Chuck Baier" wrote in message
om...
Our marina has a problem at some slips with stray current. Some of the
boats are loosing zincs at a fast rate while others are not. Looking
for some help in trying to resolve this and what kind of equipment
will I need. Thanks. Chuck

Here's one scenario.
The shore power distribution hardware carries a live 115 volt AC line,
a neutral line and a ground line.

As likely as not, the ground line is connected physically to the
neutral line at some closeby point. (For ALL slips)

Or if not, some misguided owner may connect his neutral lead to ground
return, with much the same effect.

This notional ground may have several volts imposed on it by the
voltage drop in the neutral return.
If you carry the ground on board to a through hull, this potential can
drive a current to the ACTUAL ground (below the water)

Brian W

On 21 Apr 2004 16:49:29 -0700, (Chuck Baier)
wrote:

Thanks for the input from everyone. One thing that is puzzling here.
Each slip is a separate home run to a meter. None of the slips are
interconnected. Each is independent. If this is the case leakage from
other bots on the ground shouldn't affect my zincs. We are looking for
a source that is outside the AC connections. At least that is what I
beleive.


"geneb321" wrote in message ...
There is an excellent article on testing for grounding problems between
shore power and boat at: http://www.yandina.com/electrolysis.htm
Gene
SV Sea Gypsy

"Chuck Baier" wrote in message
om...
Our marina has a problem at some slips with stray current. Some of the
boats are loosing zincs at a fast rate while others are not. Looking
for some help in trying to resolve this and what kind of equipment
will I need. Thanks. Chuck

On Wed, 21 Apr 2004 10:27:36 -0400, Jean Dufour
wrote:

Rodney Myrvaagnes wrote:

Chuck Baier wrote:

When we had the problem, we had no DC connection to the dock. We used
a trickle charger with isolation. We never have had a DC connection,
but when the ground was fixed, the zincs stopped going away.

Huh? DC to the dock? I presume you meant AC!?


No, I meant the direct coupling of the ground wire. When we used a
trickle charger it had an isolation transformer and was not grounded.
Hence, no DC connection even when there was AC.

Sorry that wasn't clear.




Rodney Myrvaagnes NYC J36 Gjo/a


Capsizing under chute, and having the chute rise and fill without tangling, all while Mark and Sally are still behind you

On Wed, 21 Apr 2004 10:27:36 -0400, Jean Dufour
wrote:

Rodney Myrvaagnes wrote:

Chuck Baier wrote:

When we had the problem, we had no DC connection to the dock. We used
a trickle charger with isolation. We never have had a DC connection,
but when the ground was fixed, the zincs stopped going away.

Huh? DC to the dock? I presume you meant AC!?


No, I meant the direct coupling of the ground wire. When we used a
trickle charger it had an isolation transformer and was not grounded.
Hence, no DC connection even when there was AC.

Sorry that wasn't clear.




Rodney Myrvaagnes NYC J36 Gjo/a


Capsizing under chute, and having the chute rise and fill without tangling, all while Mark and Sally are still behind you

OK but if stray voltage entered the ground and was causing problems
for my boat or others through the shore power connections would that
not show up in my outlets on the boat. I don't have isolators as of
yet. All the tests I have run on my power cord (new) and my 110
outlets show nothing out of the ordinary. Chuck


Brian Whatcott wrote in message . ..
Here's one scenario.
The shore power distribution hardware carries a live 115 volt AC line,
a neutral line and a ground line.

As likely as not, the ground line is connected physically to the
neutral line at some closeby point. (For ALL slips)

Or if not, some misguided owner may connect his neutral lead to ground
return, with much the same effect.

This notional ground may have several volts imposed on it by the
voltage drop in the neutral return.
If you carry the ground on board to a through hull, this potential can
drive a current to the ACTUAL ground (below the water)

Brian W

On 21 Apr 2004 16:49:29 -0700, (Chuck Baier)
wrote:

Thanks for the input from everyone. One thing that is puzzling here.
Each slip is a separate home run to a meter. None of the slips are
interconnected. Each is independent. If this is the case leakage from
other bots on the ground shouldn't affect my zincs. We are looking for
a source that is outside the AC connections. At least that is what I
beleive.


"geneb321" wrote in message ...
There is an excellent article on testing for grounding problems between
shore power and boat at: http://www.yandina.com/electrolysis.htm
Gene
SV Sea Gypsy

"Chuck Baier" wrote in message
om...
Our marina has a problem at some slips with stray current. Some of the
boats are loosing zincs at a fast rate while others are not. Looking
for some help in trying to resolve this and what kind of equipment
will I need. Thanks. Chuck

OK but if stray voltage entered the ground and was causing problems
for my boat or others through the shore power connections would that
not show up in my outlets on the boat. I don't have isolators as of
yet. All the tests I have run on my power cord (new) and my 110
outlets show nothing out of the ordinary. Chuck


Brian Whatcott wrote in message . ..
Here's one scenario.
The shore power distribution hardware carries a live 115 volt AC line,
a neutral line and a ground line.

As likely as not, the ground line is connected physically to the
neutral line at some closeby point. (For ALL slips)

Or if not, some misguided owner may connect his neutral lead to ground
return, with much the same effect.

This notional ground may have several volts imposed on it by the
voltage drop in the neutral return.
If you carry the ground on board to a through hull, this potential can
drive a current to the ACTUAL ground (below the water)

Brian W

On 21 Apr 2004 16:49:29 -0700, (Chuck Baier)
wrote:

Thanks for the input from everyone. One thing that is puzzling here.
Each slip is a separate home run to a meter. None of the slips are
interconnected. Each is independent. If this is the case leakage from
other bots on the ground shouldn't affect my zincs. We are looking for
a source that is outside the AC connections. At least that is what I
beleive.


"geneb321" wrote in message ...
There is an excellent article on testing for grounding problems between
shore power and boat at: http://www.yandina.com/electrolysis.htm
Gene
SV Sea Gypsy

"Chuck Baier" wrote in message
om...
Our marina has a problem at some slips with stray current. Some of the
boats are loosing zincs at a fast rate while others are not. Looking
for some help in trying to resolve this and what kind of equipment
will I need. Thanks. Chuck

How would you know if the boat power outlet grounds were floating 0.6
volts away from "real actual" ground potential? That's all it would
take.

Off the top: if you had a metallic anchor pathway, checking the volts
between that and a power line ground might be interesting.

Brian W



On 22 Apr 2004 15:09:22 -0700, (Chuck Baier)
wrote:

OK but if stray voltage entered the ground and was causing problems
for my boat or others through the shore power connections would that
not show up in my outlets on the boat. I don't have isolators as of
yet. All the tests I have run on my power cord (new) and my 110
outlets show nothing out of the ordinary. Chuck


Brian Whatcott wrote in message . ..
Here's one scenario.
The shore power distribution hardware carries a live 115 volt AC line,
a neutral line and a ground line.

As likely as not, the ground line is connected physically to the
neutral line at some closeby point. (For ALL slips)

Or if not, some misguided owner may connect his neutral lead to ground
return, with much the same effect.

This notional ground may have several volts imposed on it by the
voltage drop in the neutral return.
If you carry the ground on board to a through hull, this potential can
drive a current to the ACTUAL ground (below the water)

Brian W

On 21 Apr 2004 16:49:29 -0700, (Chuck Baier)
wrote:

Thanks for the input from everyone. One thing that is puzzling here.
Each slip is a separate home run to a meter. None of the slips are
interconnected. Each is independent. If this is the case leakage from
other bots on the ground shouldn't affect my zincs. We are looking for
a source that is outside the AC connections. At least that is what I
beleive.


"geneb321" wrote in message ...
There is an excellent article on testing for grounding problems between
shore power and boat at: http://www.yandina.com/electrolysis.htm
Gene
SV Sea Gypsy

"Chuck Baier" wrote in message
om...
Our marina has a problem at some slips with stray current. Some of the
boats are loosing zincs at a fast rate while others are not. Looking
for some help in trying to resolve this and what kind of equipment
will I need. Thanks. Chuck

How would you know if the boat power outlet grounds were floating 0.6
volts away from "real actual" ground potential? That's all it would
take.

Off the top: if you had a metallic anchor pathway, checking the volts
between that and a power line ground might be interesting.

Brian W



On 22 Apr 2004 15:09:22 -0700, (Chuck Baier)
wrote:

OK but if stray voltage entered the ground and was causing problems
for my boat or others through the shore power connections would that
not show up in my outlets on the boat. I don't have isolators as of
yet. All the tests I have run on my power cord (new) and my 110
outlets show nothing out of the ordinary. Chuck


Brian Whatcott wrote in message . ..
Here's one scenario.
The shore power distribution hardware carries a live 115 volt AC line,
a neutral line and a ground line.

As likely as not, the ground line is connected physically to the
neutral line at some closeby point. (For ALL slips)

Or if not, some misguided owner may connect his neutral lead to ground
return, with much the same effect.

This notional ground may have several volts imposed on it by the
voltage drop in the neutral return.
If you carry the ground on board to a through hull, this potential can
drive a current to the ACTUAL ground (below the water)

Brian W

On 21 Apr 2004 16:49:29 -0700, (Chuck Baier)
wrote:

Thanks for the input from everyone. One thing that is puzzling here.
Each slip is a separate home run to a meter. None of the slips are
interconnected. Each is independent. If this is the case leakage from
other bots on the ground shouldn't affect my zincs. We are looking for
a source that is outside the AC connections. At least that is what I
beleive.


"geneb321" wrote in message ...
There is an excellent article on testing for grounding problems between
shore power and boat at: http://www.yandina.com/electrolysis.htm
Gene
SV Sea Gypsy

"Chuck Baier" wrote in message
om...
Our marina has a problem at some slips with stray current. Some of the
boats are loosing zincs at a fast rate while others are not. Looking
for some help in trying to resolve this and what kind of equipment
will I need. Thanks. Chuck

The easiest way to check for stray voltage is to disconnect your shore
power cord and connect a milliameter between the shore power ground
pin and the boats ground pin of the connector. If you get more than a
few milliamps DC current you have problems. If you check the voltage
between those two points it will probably be below .5 volts. But that
is still enough to cause current to flow.

An isolator has two back to back diodes in it and will not allow
current to flow when the DC voltage difference is below around .6
volts. That effectively breaks your ground connection for the low DC
current that causes the problems.

Regards
Gary


On 22 Apr 2004 15:09:22 -0700, (Chuck Baier)
wrote:

OK but if stray voltage entered the ground and was causing problems
for my boat or others through the shore power connections would that
not show up in my outlets on the boat. I don't have isolators as of
yet. All the tests I have run on my power cord (new) and my 110
outlets show nothing out of the ordinary. Chuck


Brian Whatcott wrote in message . ..
Here's one scenario.
The shore power distribution hardware carries a live 115 volt AC line,
a neutral line and a ground line.

As likely as not, the ground line is connected physically to the
neutral line at some closeby point. (For ALL slips)

Or if not, some misguided owner may connect his neutral lead to ground
return, with much the same effect.

This notional ground may have several volts imposed on it by the
voltage drop in the neutral return.
If you carry the ground on board to a through hull, this potential can
drive a current to the ACTUAL ground (below the water)

Brian W

On 21 Apr 2004 16:49:29 -0700, (Chuck Baier)
wrote:

Thanks for the input from everyone. One thing that is puzzling here.
Each slip is a separate home run to a meter. None of the slips are
interconnected. Each is independent. If this is the case leakage from
other bots on the ground shouldn't affect my zincs. We are looking for
a source that is outside the AC connections. At least that is what I
beleive.


"geneb321" wrote in message ...
There is an excellent article on testing for grounding problems between
shore power and boat at: http://www.yandina.com/electrolysis.htm
Gene
SV Sea Gypsy

"Chuck Baier" wrote in message
om...
Our marina has a problem at some slips with stray current. Some of the
boats are loosing zincs at a fast rate while others are not. Looking
for some help in trying to resolve this and what kind of equipment
will I need. Thanks. Chuck