Should I get scared?

[Gusshr]

I was watching some fun boat videos online about grounds and ground leak and I ended up in the boat using a clamp AMP meter reading 0.5 AMP (thats the 4 wires 2 hot, one neutral and one ground together) when all AC breakers are on running mainly the battery charger/inverter. I went to investigate further as usual, so I shut off all AC breakers including the charger/inverter supply, and with leaving only the main (shore vs Gen) selector switch on, now I measure 1.5 Amp!!! I tested the wires individually (luckily they are connected on a bus bar in the forward anchor locker) and I found out that the 1.5 Amp is measured on the white line only!!

The funny thing is that the black line is reading "0" and the red line is reading "0". Obviously the green was "0" since I have a ground isolator that I have installed when I first got the boat and it reduced the consumption of Zincs by half.

With the black and red measuring zeros, where is the 1.5 amp AC current on the neutral line coming from????!!!!

Everything on the boat was shutoff at the time of measurement.

By the way when I turn the main switch (shore vs gen) to off nothing passes and everything measure zero.

Help Please

 

[Gusshr]

This is an educational page about measuring the shore line AMP for leakage. https://www.marinadockage.com/technical-bulletin-understanding-ac-leakage-current/

 

[krush]

Clamp meters are good tools. But what you are using it for is asking too much of its accuracy.

 

[Pete]

Take two additional measurements, leaving the "clamp on" on the white wire in the same position. First with the clamp on still reading 1.5 amps, turn off the 50 amp dual pole breaker at the pedestal serving your shore power cord. Note any change in the clamp on reading. Next, with everything remaining the same, remove your shore power cord connector from the pedestal outlet, and note what change you see, if any?

Post your results back to the group

 

[Gusshr]

Test results:

Main boat breaker that feeds the electrical panel is in the OFF position in all tests. Source selector switch (Gen vs Shore vs Off) is on Shore (this switch feeds the Main boat Breaker

1- with dock pedestal breaker ON, the shore cable is inserted in the pedestal, I measure 1.27 AMP on the white neutral cable as it enters the boat

2- with dock pedestal breaker OFF, the shore cable is inserted in the pedestal, I measure 1.36 AMP on the white neutral cable as it enters the boat

3- with the shore cable unplugged, I measure 0 AMP on the white neutral cable as it enters the boat.

4- with the dock pedestal breaker off I couldn't measure any voltage between any of the prongs in the receptacle!

 

[Gusshr]

Take two additional measurements, leaving the "clamp on" on the white wire in the same position. First with the clamp on still reading 1.5 amps, turn off the 50 amp dual pole breaker at the pedestal serving your shore power cord. Note any change in the clamp on reading. Next, with everything remaining the same, remove your shore power cord connector from the pedestal outlet, and note what change you see, if any?

Post your results back to the group

I posted the test results.Do I have a dock power problem?

 

[Pete]

Could be a shore power problem, but more data required for a conclusion. SAFETY, SAFETY is the primary requirement. If at any time you are not 100% positive of how to do something electrical safely, get knowledgeable help.

With that said and emphasized, the next measurement is at your pedestal service outlet. Turn off your double 50 amp pedestal breaker. Next remove your shore power cable connector from this outlet. You will now need a voltage measuring device, a separate multimeter of perhaps your clamp on also has voltage measurement scales. Whichever instrument you use, you will have two leads. Colors do not matter for this measurement. Set the scale on the instrument to "AC volts" 120 volts or next higher scale. With the pedestal 50 breaker off and your shore power cable disconnected, hold one probe with a good connection to the metal shell of the 50 amp pedestal outlet. Next, one at a time insert the second probe into the female blade terminals on the face of the pedestal. Watch for any reaction on the meter as you move the probe inside each of the terminals. Any results?

Of particular interest is the terminal that does not have a 90 degree tab. Two terminals will, these are the hot legs. One will not, this is your white wire neutral. These terminal and the outer shell tend to corrode, so be sure to get good connections with the probes. Move them around doing the measurement. All you are looking for is some sort of reaction on your meter, not a precise measurement.

 

[Gusshr]

Could be a shore power problem, but more data required for a conclusion. SAFETY, SAFETY is the primary requirement. If at any time you are not 100% positive of how to do something electrical safely, get knowledgeable help.

With that said and emphasized, the next measurement is at your pedestal service outlet. Turn off your double 50 amp pedestal breaker. Next remove your shore power cable connector from this outlet. You will now need a voltage measuring device, a separate multimeter of perhaps your clamp on also has voltage measurement scales. Whichever instrument you use, you will have two leads. Colors do not matter for this measurement. Set the scale on the instrument to "AC volts" 120 volts or next higher scale. With the pedestal 50 breaker off and your shore power cable disconnected, hold one probe with a good connection to the metal shell of the 50 amp pedestal outlet. Next, one at a time insert the second probe into the female blade terminals on the face of the pedestal. Watch for any reaction on the meter as you move the probe inside each of the terminals. Any results?

Of particular interest is the terminal that does not have a 90 degree tab. Two terminals will, these are the hot legs. One will not, this is your white wire neutral. These terminal and the outer shell tend to corrode, so be sure to get good connections with the probes. Move them around doing the measurement. All you are looking for is some sort of reaction on your meter, not a precise measurement.

getting zeros except between one of the hot lines with the breaker off and the ground rim getting one volt!!

 

[Pete]

This is now getting difficult without a wiring diagram for your boat. But lets try checking the green wire isolator. People wire many different ways, but I am not aware of any configuration that ties the green and white wire together on the boat when using shore power. So lets try this. Connect the shore power back to where you see the 1.3 amp reading on the white wire. Make sure your inverter is off. Next remove your shore power cable from the pedestal. Now connect one lead of you voltage reading meter anywhere inside the boat to the white wire. Set the voltage meter to a low voltage scale, around 5 volts,and touch the other lead to each green wire on the isolator, one at a time. If you see no reaction on the meter, change the scale to resistance on your meter set at the lowest scale. Again with one meter probe attached to the white wire touch each green wire on the isolator. Then swap the leads in the meter and try it again. Use AC and DC scales on all measurements. Yes, overkill on the various measurement but we are looking for some reaction. Does the meter react?

 

[Pete]

Here is a very quick but telling test. Remove your shore power cable at the boat. Leave the selector switches set for shore power as your source. Verify the inverter is off. Next choose any standard 120 volt wall outlet.

You are interested in the round ground connector and the LONGER of the two slotted connectors. The shorter of the slotted connectors is the hot lead that is not used at this time. First use your volt meter to check for any voltage between the ground connector and the longer, neutral, slotted connector. There should be none. If so, set your meter to the ohms/continuity scale and again measure between the round ground pin and the longer slotted pin. You should see no continuity/infinite ohms.

What are your results?

 

[Gusshr]

This is now getting difficult without a wiring diagram for your boat. But lets try checking the green wire isolator. People wire many different ways, but I am not aware of any configuration that ties the green and white wire together on the boat when using shore power. So lets try this. Connect the shore power back to where you see the 1.3 amp reading on the white wire. Make sure your inverter is off. Next remove your shore power cable from the pedestal. Now connect one lead of you voltage reading meter anywhere inside the boat to the white wire. Set the voltage meter to a low voltage scale, around 5 volts,and touch the other lead to each green wire on the isolator, one at a time. If you see no reaction on the meter, change the scale to resistance on your meter set at the lowest scale. Again with one meter probe attached to the white wire touch each green wire on the isolator. Then swap the leads in the meter and try it again. Use AC and DC scales on all measurements. Yes, overkill on the various measurement but we are looking for some reaction. Does the meter react?

Results: no voltage (ac or dc) between the white and either sides of the isolator and the resistance is .3-.4 ohms between the white and the green wire in the boat even when swapping test prongs.

 

[Gusshr]

Here is a very quick but telling test. Remove your shore power cable at the boat. Leave the selector switches set for shore power as your source. Verify the inverter is off. Next choose any standard 120 volt wall outlet.You are interested in the round ground connector and the LONGER of the two slotted connectors. The shorter of the slotted connectors is the hot lead that is not used at this time. First use your volt meter to check for any voltage between the ground connector and the longer, neutral, slotted connector. There should be none. If so, set your meter to the ohms/continuity scale and again measure between the round ground pin and the longer slotted pin. You should see no continuity/infinite ohms.What are your results?

I thought that the white and the ground should connect on the boat to be compliant with the code and prevent swimmers risk in case of a short.

 

[Pete]

If another member, familiar with NMEA specs for non isolation transformer boats knows different, please chime in.

However, the answer to your question is NO. Let me start with one of the cardinal rules of 240/120 wiring. The white wire and the green wire are connected at one place only, that is at the source of the electric power, on the secondary of a transformer feeding the load. At this point the white and green wire are also connected to an earth ground using a bare wire attached to a driven earth ground rod. The green wire then proceeds down the dock, with each pedestal attached, providing the earth ground safety to protect the boats and anyone in the water. That green safety is attached to the boat bonding system. In your case the earth ground goes through a galvanic isolator before connecting to the bonding system. The white wire then proceeds to all the boats acting as a current balance return for all the red and black voltage wires. Without getting in too deep the current in the white wire varies based on the the difference in the load on the black versus red wire. The point is the white conductor is a electrically charged line sometimes, in fact most of the time.

With that background what happens if you tie the white wire and the green wire together on your boat, likely at the breaker panel for the incoming electric service? Note that breaker panel is a sub panel, not the main panel in the system and should not join the green and white wires together. First, the white wire is now a connection around your galvanic isolator, so it is totally ineffective. Next, the white wire is now attached to your safety ground injecting electricity into the floatation water creating a hazard. Since you are in Boca, I assume your flotation water is ocean salty, which makes the hazard minimum.

So the suggestion to solve you shore power connection problem is simple, but I stop short of recommending it, as I do not know how the inverter and generator are wired and each of them have to provide white/green wire bonding when activated. If you want to just give it a try, remove the shore power connector, make sure the inverter if off, and then remove the white where it joins the green wire on the boat. Just tape the white wire connector and let it hang in free air. Plug the shore power cable back in, and check your white wire in the configuration that gave you your 1.3 amp reading. Did it go to zero? If it did, good news, but put the white wire back where you disconnected it until you can get a marine electrician to verify correct neutral/white wire bonding for shore power, the inverter, and the generator.

 

[SKYCHENEY]

Option #2: Buy an isolation transformer and have that marine electrician install it.

 

[Gusshr]

If another member, familiar with NMEA specs for non isolation transformer boats knows different, please chime in.

However, the answer to your question is NO. Let me start with one of the cardinal rules of 240/120 wiring. The white wire and the green wire are connected at one place only, that is at the source of the electric power, on the secondary of a transformer feeding the load. At this point the white and green wire are also connected to an earth ground using a bare wire attached to a driven earth ground rod. The green wire then proceeds down the dock, with each pedestal attached, providing the earth ground safety to protect the boats and anyone in the water. That green safety is attached to the boat bonding system. In your case the earth ground goes through a galvanic isolator before connecting to the bonding system. The white wire then proceeds to all the boats acting as a current balance return for all the red and black voltage wires. Without getting in too deep the current in the white wire varies based on the the difference in the load on the black versus red wire. The point is the white conductor is a electrically charged line sometimes, in fact most of the time.

With that background what happens if you tie the white wire and the green wire together on your boat, likely at the breaker panel for the incoming electric service? Note that breaker panel is a sub panel, not the main panel in the system and should not join the green and white wires together. First, the white wire is now a connection around your galvanic isolator, so it is totally ineffective. Next, the white wire is now attached to your safety ground injecting electricity into the floatation water creating a hazard. Since you are in Boca, I assume your flotation water is ocean salty, which makes the hazard minimum.

So the suggestion to solve you shore power connection problem is simple, but I stop short of recommending it, as I do not know how the inverter and generator are wired and each of them have to provide white/green wire bonding when activated. If you want to just give it a try, remove the shore power connector, make sure the inverter if off, and then remove the white where it joins the green wire on the boat. Just tape the white wire connector and let it hang in free air. Plug the shore power cable back in, and check your white wire in the configuration that gave you your 1.3 amp reading. Did it go to zero? If it did, good news, but put the white wire back where you disconnected it until you can get a marine electrician to verify correct neutral/white wire bonding for shore power, the inverter, and the generator.

I thank you for the detailed info. I guess having an inverter and a generator makes things even more complicated. I will first look at the power selection switch (shore vs Gen) and see if it is also switching ground or not where it is supposed to connect ground and neutral when on generator but not on shore power, and then go from there.