How can I find the ground fault in my boat?

[Qsilverrdc]

Last weekend I went to Put-In-Bay, and plugged in to shore power. When I turned on my panel there was no power. Also the three boats next to me were (now) without power. The dock master told me that mu boat had tripped the ground fault at the street, and that the three boats were GFCI tied together. I was a bit surprised as I have never had any issues anywhere. He told me the system was new, and a few boats have had problems. Some shore cables, some adapters, most boat problems.
Well I was able to run my generator so I had some AC on this hot weekend. Since power was limited I defrosted the freezer. The ice survived long enough to serve it's intended purpose.

I really don't want to have this happen again, so how can I diagnose the problem(s) at my home port where I don't have a problem?

Here is what I know and don't know.:huh:

I don't know if my home dock has a GFCI breaker.
I know that I do not have power issues at my home dock.
At Put-In-Bay I was able to turn on the panel main switch with all breakers off and not get a fault.
I was only able to test 2 different breakers. Both tripped the dock GFCI immediately.
The other neighbors and Dock master were getting tired of me causing trips, so I stopped testing.

So I have not been able to eliminate the shore cable, Y cable, or my boat.

How can I figure out the problem? I cannot reproduce the ground fault trip at my home dock.

I have good electrical skills, but could use some thoughts.

Please help.

 

[JJ Chones]

Use a clamp on ampmeter and clamp it around your shore power cable with the boats a/c breakers all in the off position. Start with the main breakers turning them on and watching for any reading on the ampmeter. Then on to each individual breaker until you find the problem. You also have to make sure each appliance or controlled device turns on. Like the hot water heater, stove, air conditioners.

 

[dvx216]

Check your home dock breakers for a GFIC . It could have been a over current trip at Put in bay as well as a faulty to ground. There is no way to tell what caused the trip at PB.

 

[ttmott]

The GFCI measures current flowing through the hot leg and compares it to the current flowing through the neutral leg. If it does not see equal current in both legs it will trip as there is a current leak somewhere else like the ground conductor or something else. If your neutrals are crossed in the boat's wiring between the two 120VAC circuits and the marina's GFCI does not collect all the neutrals and all of the hots the marina's GFCI will not see equal returned current and trip. So you might want to verify the hot legs and neutral legs are on the same circuits.

 

[Qsilverrdc]

Check your home dock breakers for a GFIC . It could have been a over current trip at Put in bay as well as a faulty to ground. There is no way to tell what caused the trip at PB.

They know it is a ground fault. The pedestals have local breakers. Also they said they see this fairly often.
The equipment is new end of last season.
I wish it was as simple as over-current trip.

 

[Qsilverrdc]

Use a clamp on ammeter and clamp it around your shore power cable with the boats a/c breakers all in the off position. Start with the main breakers turning them on and watching for any reading on the ammeter. Then on to each individual breaker until you find the problem. You also have to make sure each appliance or controlled device turns on. Like the hot water heater, stove, air conditioners.

If I clamp it around the shore power cable at my marina, won't it read zero, unless my boat is leaking current to the water?
Or is it, if a ground fault exists the boat will be leaking current into the water?

Thanks

 

[JJ Chones]

If I clamp it around the shore power cable at my marina, won't it read zero, unless my boat is leaking current to the water?
It will read 0v unless there is a ground fault on the a/c system. It COULD be leaking current to the water depending on your grounding, bonding and other factors.

Or is it, if a ground fault exists the boat will be leaking current into the water?
It "could" be leaking current to the water.

Thanks

Either way, not a safe situation.

 

[JJ Chones]

Oops. I posted my reply in the quotes. Damn tapatalk

 

[northshore]

There is a minimal amount of leakage that is acceptable. This according to the sparky that just checked our club out as we do not have GFCI's installed yet. He went to every outlet with the appropriate meter and anyone over 'X' got the red tape stripe.
My question for that dock master would be this, how is he certain it was your fault? If you were the last one to plug in, you may have just pushed that GFCI over its limit even though you may have been under some acceptable limit. Possibly the guy next to you was over the limit and you just had the bad luck of plugging in last.

BTW what were the two breakers that caused the trip?

If you really get hung up, I could find out the guys name and if he is on the west side of Cleveland, maybe he would not mind a trip to Vermilion. PM me if you want me to find out.

One way or another, I would get someone who knows what they are doing to check it - nothing to screw around with.

 

[HUMPH]

The GFCI measures current flowing through the hot leg and compares it to the current flowing through the neutral leg. If it does not see equal current in both legs it will trip as there is a current leak somewhere else like the ground conductor or something else. If your neutrals are crossed in the boat's wiring between the two 120VAC circuits and the marina's GFCI does not collect all the neutrals and all of the hots the marina's GFCI will not see equal returned current and trip. So you might want to verify the hot legs and neutral legs are on the same circuits.

It could also be a neutral to ground situation. Even a single strand touching will trip a GFI.

 

[ttmott]

Here is another thought
First switch all the boats AC breakers off or open including the power cable mains and generator.
With a DVM:
1. measure resistance between each of the hot legs to ground on the power cords at the dock side interface and write down that value; should be a very high value or infinity
2. measure resistance between each of the neutral legs to ground on the power cords at the dock side interface and write down that value should be a very high value or infinity and close to equal to 1
3. switch on the power cable mains and re-perform 1 and 2
4. one by one close breakers and measure 1 and 2
In theory there should be no change in resistance between the hot and ground and neutral and ground as you stage through the breakers. If one of the tests shows a significant change in resistance between the hot or neutral and ground then there is your leak; somewhere in that breaker's circuit.
As a note when AC motors get older and are exposed to the elements like your water pump the windings will tend to slightly leak to ground. Water heater terminations in the engine room can have a leak to ground. Quite possible several things are accumulating leakage on the hot or neutral and realizing the GFCI trip. Again, old rotating equipment are notorious for current leakage. Note also an onboard GFCI if defective can cause an upstream GFCI to trip; that can get a bit complicated and will require removal of GFCI's to isolate such a problem.

 

[Qsilverrdc]

Thanks for the thoughts. I have ordered a newer up to date volt meter with clamp on ammeter that can measure down to 10ma. I know that is above a 5ma ground fault level but for the meter cost value it's a good start for me.

I think I will do the clamp around shore power cord first with most everything running. This should tell me how much I am leaking to the lake. I don't expect this to be a huge number, but you never know.

If there is no current (measurable) leaking then I will need to measure the Hot-Neutral pair only.
I will have to see if I can get access inside the pedestal and clamp around the Hot-Neutral pair. If not then I will need to cut into a cord set something like this (https://gilwellbear.files.wordpress.com/2013/01/dscn4171.jpg) So I can measure the H-N pair and get the lost current.

In either case I can test circuits on one at a time (under load) and measure the H-N pair current, or leak to lake.
At this time I suspect I have a neutral to ground bond (short) somewhere in the boat. Possibly a bad water heater coil or AC unit(s) as suggested.

After taking measurements, I will start pulling neutrals one at a time. Until I isolate the problem appliance neutral, and go from there.

I don't think it is a hot to ground leak, (like a bad motor) because every circuit tested so far caused the dock GFI trip. I know that doesn't mean I don't have leaking AC devices, I'm just not suspecting that at this moment. I should find out from the breaker switching and load tests if I do.

Richard

 

[Qsilverrdc]

Here is another thought
First switch all the boats AC breakers off or open including the power cable mains and generator.
With a DVM:
1. measure resistance between each of the hot legs to ground on the power cords at the dock side interface and write down that value; should be a very high value or infinity.{snip}....

Attention - for others that may try this procedure. Please remember that the boat is never connected to shore power for this testing! This is a resistance test only.

I will also try these 4 steps as it also tests the cord for a neutral to ground short. Could be very telling.
I will try and update my results as I get some testing done.

 

[Qsilverrdc]

There is a minimal amount of leakage that is acceptable. {snip}
My question for that dock master would be this, how is he certain it was your fault? If you were the last one to plug in, you may have just pushed that GFCI over its limit even though you may have been under some acceptable limit. Possibly the guy next to you was over the limit and you just had the bad luck of plugging in last.

BTW what were the two breakers that caused the trip?
{snip}

Breakers Tried - Galley Systems & AC converter.

My AC panel has the old style reverse polarity neon lamp checkers. ALCO GT33. These leak about 2ma line to ground, and there are 2 on my boat so 4ma. They are like the 3 light plug polarity testers you can buy. I actually don't think mine are working (they appear burned out) so probably not leaking any current. Anyway they did not cause a trip.

I believe the 2011 NEC says not exceeding 100ma to ground. I think that is going down to 30ma in the future. I would guess that PIB is set at 100ma for the 3 pedestals (could be 30ma). Since I was last on the chain...yeah... the 2 other boats could be leaking just below the trip, and me at only @ 10ma. I will find out for sure when I test my boat. How could the dock master tell?. Any 2 boats plugged in would work. The result would be first come, first plugged in... lol.. Anyway they were nice and gave me a fee discount..

 

[Ike]

As was said, nothing to fool around with. Sounds like reverse polarity. If you are on an old shore system at your regular dock, it may not sense the reverse polarity. I would recommend hiring a certified marine electrician to troubleshoot this. You may be able to do this yourself, but it will take you a long time. A marine electrician will do it faster and you will be more assured that the problem is fixed. This could be life threatening if not fixed so best get it done.

 

[tony1b2000]

Is this a intermittent problem or do you trip it every time you plug into shore power? Do you have an "OLD" refrigerator on the boat or OLD AC unit? Compressors (motor loads ) are notorious for tripping ground faults. Try keeping the breaker off for the fridge for a few days and see if you are still tripping the marina's gfci. If it still trips, try shutting the AC off for a few days. If this a intermittent problem, a meter may not show it. Thus you may have to find it by process of elimination (Breaker by breaker). One other thing to check. Moisture in your 110 outlets can cause the problem as well if you have any outlets that may have been exposed to rain. The gaskets out the outlet covers do not last forever. BTW, I am a master electrician.
Keep us posted!

 

[northshore]

Breakers Tried - Galley Systems & AC converter.

My AC panel has the old style reverse polarity neon lamp checkers. ALCO GT33. These leak about 2ma line to ground, and there are 2 on my boat so 4ma. They are like the 3 light plug polarity testers you can buy. I actually don't think mine are working (they appear burned out) so probably not leaking any current. Anyway they did not cause a trip.

I believe the 2011 NEC says not exceeding 100ma to ground. I think that is going down to 30ma in the future. I would guess that PIB is set at 100ma for the 3 pedestals (could be 30ma). Since I was last on the chain...yeah... the 2 other boats could be leaking just below the trip, and me at only @ 10ma. I will find out for sure when I test my boat. How could the dock master tell?. Any 2 boats plugged in would work. The result would be first come, first plugged in... lol.. Anyway they were nice and gave me a fee discount..

Myself and the guy responsible for looking into GFCI's at Edgewater had a long discussion about where to put them. When we were discussing having them at the end of a dock (covering all boats on that doc) the reality of nuisance trips(individually OK, but in aggregate, over the limit) became quite clear. Having one every few boats would lessen the possibility but it could still happen as I think you may have just found out.

-Mike

 

[Qsilverrdc]

As was said, nothing to fool around with. Sounds like reverse polarity. If you are on an old shore system at your regular dock, it may not sense the reverse polarity. I would recommend hiring a certified marine electrician to troubleshoot this. You may be able to do this yourself, but it will take you a long time. A marine electrician will do it faster and you will be more assured that the problem is fixed. This could be life threatening if not fixed so best get it done.

Hi,
Thanks for the though but, no it's not reverse polarity. Reverse polarity is problem with the dock pedestal wiring with hot and neutrals reversed.

Here is a decent document from EATON Corp (c) that talks about ground fault sensing.
http://sabercathost.com/1TRp/Electric_Shock_Drowning_-_ABYC(1).pdf

Richard

 

[Qsilverrdc]

Is this a intermittent problem or do you trip it every time you plug into shore power? Do you have an "OLD" refrigerator on the boat or OLD AC unit? Compressors (motor loads ) are notorious for tripping ground faults. Try keeping the breaker off for the fridge for a few days and see if you are still tripping the marina's gfci. If it still trips, try shutting the AC off for a few days. If this a intermittent problem, a meter may not show it. Thus you may have to find it by process of elimination (Breaker by breaker). One other thing to check. Moisture in your 110 outlets can cause the problem as well if you have any outlets that may have been exposed to rain. The gaskets out the outlet covers do not last forever. BTW, I am a master electrician.
Keep us posted!

Never had a problem since owning the boat 6 years now. This tripp is unique to the Put-In-Bay dock that I was visiting. The problem is I just can't pack up the tools and head over to Put-In-Bat to troubleshoot, although it would be fun. At this point I suspect I have a problem and will diagnose. As more and more docks upgrade to meet new requirements this problem may show up increasingly.

Thanks, Richard

 

[Qsilverrdc]

Myself and the guy responsible for looking into GFCI's at Edgewater had a long discussion about where to put them. When we were discussing having them at the end of a dock (covering all boats on that doc) the reality of nuisance trips(individually OK, but in aggregate, over the limit) became quite clear. Having one every few boats would lessen the possibility but it could still happen as I think you may have just found out.

-Mike

Hi Mike,

This article by Eaton (c) covers a lot about the marina side and ground faults.
http://sabercathost.com/1TRp/Electric_Shock_Drowning_-_ABYC(1).pdf

Without individual pedestal monitoring how do you know who is using more than their portion of allowable ground fault current when grouped?

Richard