Stray Current

[Jeff58]

I have a R29 S 2024 model year tug. My marina tests for stray current around vessels at the dock. They detected current at the aft of our boat around the swim platform (port, starboard, middle) and nowhere else. They use a floating sensor that beeps and flashes a red light when current is present... not an overly sophisticated device. When unplugged from shore power the problem is eliminated. I am in fresh water and only run the battery charger and refrigerators at the dock. I have not noticed any unusual anode issues although the boat is only on the second season. I moved the boat to the transient side of the marina, which has a new electrical drop and shore posts and the problem continues.

The marina in general is old and was built on a previous rail yard so the only "earth" is the top few inches otherwise it is railroad ballast (rock). Not sure this is relevant, but makes me wonder about the grounding side of the grid.

Is there a switch, other than the main shore power breaker on the panel to shutdown the Kiase battery charger that I am missing?
I am very interested in guidance on where and how to start in diagnosing and correcting.
Thanks,
Jeff.

 

[Maggie Anne]

Boatzincs.com sells a corrosion reference electrode to measure the galvanic isolation of the boat. It seems their price has gone up a bit since I bought one but they have some good discussion on their website for on these sort of issues.

 

[Rode Trip]

This is one of the most misunderstood marine electrical topics. Like people do all the time, I think you're confusing stray DC current with an AC leakage electrical problem. Especially in fresh water, the marina is concerned with AC current in the water because that can kill people. Stray DC current can damage the underwater metals on your boat, but won't hurt anyone. Both problems are fairly easy to prevent and resolve, but I'll focus on the AC issue because that's more likely what they're talking about and the dangerous issue.
First, all the Ranger Tugs are built with ELCI's, which measure for current on the AC grounding conductor in the event of a stray AC current on the line due to a fault in a piece of equipment on the boat. It's set to trip at 30 milliamps because that's the level that becomes dangerous. Have you pushed the test button on the ELCI and seen it trip to show it's working? With a working ELCI it's unlikely that you really have an AC leakage problem on the boat. It's whole job is to trip if that happens.
Beyond that, the best way to truly check for AC leakage is with a breakout cable and an AC clamp on meter. The break out cable lets you access the hot, neutral, and ground conductors in the shore power cable then you can clamp each one to see the current. You should see the same current on the hot and neutral, and no current on the grounding conductor.

 

[Rode Trip]

Another easy test and way to rule out a potential source of the problem is try a different shore power cord.

 

[Jeff58]

This is one of the most misunderstood marine electrical topics. Like people do all the time, I think you're confusing stray DC current with an AC leakage electrical problem. Especially in fresh water, the marina is concerned with AC current in the water because that can kill people. Stray DC current can damage the underwater metals on your boat, but won't hurt anyone. Both problems are fairly easy to prevent and resolve, but I'll focus on the AC issue because that's more likely what they're talking about and the dangerous issue.
First, all the Ranger Tugs are built with ELCI's, which measure for current on the AC grounding conductor in the event of a stray AC current on the line due to a fault in a piece of equipment on the boat. It's set to trip at 30 milliamps because that's the level that becomes dangerous. Have you pushed the test button on the ELCI and seen it trip to show it's working? With a working ELCI it's unlikely that you really have an AC leakage problem on the boat. It's whole job is to trip if that happens.
Beyond that, the best way to truly check for AC leakage is with a breakout cable and an AC clamp on meter. The break out cable lets you access the hot, neutral, and ground conductors in the shore power cable then you can clamp each one to see the current. You should see the same current on the hot and neutral, and no current on the grounding conductor.

Thanks so much. The break out cable and clamp on revealed a 0.7 milliamp loss. It is looking more and more like a marina issue.

 

[Brian John]

In a freshwater marina, I doubt your issue is DC current and associated galvanic corrosion, as noted, there are ways to determine if this is an issue.

The first question I would ask is what they are measuring, AC or DC current. Next, I would request some information on the tester they are using and how they know they are properly using the tester. (The number of electricians who have test equipment and do not understand how to utilize the tester is off the charts) If they give you information on this tester, please post that information here.

As others have said, check your shore power cord and try a different shore power cord. If you have an AC Clamp*1 that can measure low-level AC Current on the shore power cord, while measuring AC Current, turn on AC loads one at a time on the tug, and see if there is an increase in AC leakage current. An increase in AC current would lead you to believe there is an issue on your boat.

Do the dock pedestals have ELCI circuit breakers? These trip at 30 milliamps above the 7ma you noted. I would get a 5ma adaptor cord and see if that trips, when connected to shore power. The cost is minimal compared to the liability of being told you have an issue with AC leakage in a freshwater marina and doing nothing to eliminate the issue.

Ericson G200-10-2W-L630 Industrial Grade Inline GFCI - 30 Amp, 2 ft Cable

Ericson G200-10-2W-L630 G200 Industrial Grade Inline GFCI - 30 Amp - 2 ft - L6-30P PT WT, L6-30C PT WT - MANUAL - Black - 0.5" x 1" x 1" (HxLxW)

rspsupply.com

*1 An inexpensive AC Clamp may not measure accurately or reliably low-level AC current.

 

[CaspersCruiser]

First, all the Ranger Tugs are built with ELCI's,

Make that "All the Ranger Tugs built in 2012 and later are built with ELCI's"

My 2012 R27, built in the fall of 2011, does not have an ELCI. A friend's 2012 R27 actually built in 2012 does have an ELCI.

Just a point of information.....

 

[Jeff58]

In a freshwater marina, I doubt your issue is DC current and associated galvanic corrosion, as noted, there are ways to determine if this is an issue.

The first question I would ask is what they are measuring, AC or DC current. Next, I would request some information on the tester they are using and how they know they are properly using the tester. (The number of electricians who have test equipment and do not understand how to utilize the tester is off the charts) If they give you information on this tester, please post that information here.

As others have said, check your shore power cord and try a different shore power cord. If you have an AC Clamp*1 that can measure low-level AC Current on the shore power cord, while measuring AC Current, turn on AC loads one at a time on the tug, and see if there is an increase in AC leakage current. An increase in AC current would lead you to believe there is an issue on your boat.

Do the dock pedestals have ELCI circuit breakers? These trip at 30 milliamps above the 7ma you noted. I would get a 5ma adaptor cord and see if that trips, when connected to shore power. The cost is minimal compared to the liability of being told you have an issue with AC leakage in a freshwater marina and doing nothing to eliminate the issue.

Ericson G200-10-2W-L630 Industrial Grade Inline GFCI - 30 Amp, 2 ft Cable

Ericson G200-10-2W-L630 G200 Industrial Grade Inline GFCI - 30 Amp - 2 ft - L6-30P PT WT, L6-30C PT WT - MANUAL - Black - 0.5" x 1" x 1" (HxLxW)

rspsupply.com

*1 An inexpensive AC Clamp may not measure accurately or reliably low-level AC current.

A marine surveyor did the check and measured at point 7 (0.7). High dollar test piece. Marina is a mix of gfi and non-gfi. On going inspections reveal it is not a boat issue.

 

[Jeff58]

Make that "All the Ranger Tugs built in 2012 and later are built with ELCI's"

My 2012 R27, built in the fall of 2011, does not have an ELCI. A friend's 2012 R27 actually built in 2012 does have an ELCI.

Just a point of information.....

I did verify and test the ELCI so another validation it is not a boat issue.

 

[Brian John]

Make that "All the Ranger Tugs built in 2012 and later are built with ELCI's"

My 2012 R27, built in the fall of 2011, does not have an ELCI. A friend's 2012 R27 actually built in 2012 does have an ELCI.

Just a point of information.....

Did you install an ELCI? Did your Tug come with a Galvanic Isolator?