Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 18-09-2020, 11:23   #1
Registered User

Join Date: Apr 2019
Posts: 266
Marinco 50 amp shore plug shorted

I've been chasing down an intermittent issue where 120v breakers on the boat and marina pedestals would all trip at once. It didn't matter the load we were pulling and it seemed random.

Today I started testing things (I'm at anchor) and found continuity at the ship side plug between ground and neutral. After opening breakers and still seeing it, I removed the plug and still saw it (photo attached)

I couldn't see anything making contact even after completely disassembling the plug. I've now installed a Smartplug and will test that next time we're in a marina.

I'm curious if anyone has seen this issue or knows what may have caused it.
Attached Thumbnails
Click image for larger version

Name:	PXL_20200918_155212028.jpg
Views:	76
Size:	406.3 KB
ID:	223683  
crayiii is offline   Reply With Quote
Old 18-09-2020, 11:49   #2
Registered User

Join Date: Jun 2013
Location: canada
Posts: 3,193
Re: Marinco 50 amp shore plug shorted

2.4 mega ohms? That is open. No issue there.
smac999 is offline   Reply With Quote
Old 18-09-2020, 11:53   #3
Registered User

Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft Catalina 381
Posts: 1,241
Re: Marinco 50 amp shore plug shorted

Even at 120v, that would only leak 0.5 milliamps. That's highly unlikely to be the issue. And between neutral and ground, that amount of resistance is probably even less of a concern. Certainly not enough to trip a GFI.
rslifkin is online now   Reply With Quote
Old 18-09-2020, 11:59   #4
Registered User

Join Date: Apr 2019
Posts: 266
Re: Marinco 50 amp shore plug shorted

Moving the probes around resulted in higher values. It was pretty intermittent and everything tripped when there was a heavy load on the Marina's system.

Also, at one point, while trying to figure out why things were tripping and the marina said I was pulling 15 amps when I know I should have only been pulling 5 or less.

I also say the reverse polarity light in the panel dimly lit.
crayiii is offline   Reply With Quote
Old 18-09-2020, 12:03   #5
Do or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 11,315
Re: Marinco 50 amp shore plug shorted

Spray some contact cleaner and blow it out with compressed air. Its just some dirt, grease. 2.4MOhm or even more is not the cause of 30A breakers flipping, you are on the wrong track.
__________________
This is just an answer/comment; not interested in arguing or dealing with the trolls
s/v Jedi is online now   Reply With Quote
Old 18-09-2020, 12:04   #6
Registered User

Join Date: Jun 2013
Location: canada
Posts: 3,193
Re: Marinco 50 amp shore plug shorted

The ground and neutral are joined on the dock anyways.
smac999 is offline   Reply With Quote
Old 18-09-2020, 12:09   #7
Registered User

Join Date: Apr 2019
Posts: 266
Re: Marinco 50 amp shore plug shorted

I started taking the end of the 50 amp shore power cable apart and found that the cord has started pulling out. Now I'm thinking there was just a partial connection being made so it may have been pulling more amps than I thought. Possible?
Attached Thumbnails
Click image for larger version

Name:	PXL_20200918_190543310.jpg
Views:	43
Size:	314.6 KB
ID:	223684  
crayiii is offline   Reply With Quote
Old 18-09-2020, 12:20   #8
Registered User
 
CaptTom's Avatar

Join Date: Apr 2004
Location: Southern Maine
Boat: Prairie 36 Coastal Cruiser
Posts: 2,005
Re: Marinco 50 amp shore plug shorted

Quote:
Originally Posted by crayiii View Post
I also say the reverse polarity light in the panel dimly lit.
You sparked a memory with that. I read somewhere (I'm no expert) that some reverse polarity lights are simply connected to neutral and ground. If there's current there, they'll light. But they also present a path between those and will themselves cause a GFCI to trip.

That said, I imagine that light would also indicate an actual voltage difference between ground and neutral by dimly lighting. So in your case it could be the cause, or a symptom, or both.

It can be difficult to find an unwanted bond between ground and neutral. On my boat I discovered one of the neutral wires to an outlet had broken, so some wanna-be electrician simply wired the outlet to ground, instead. It worked fine until the boat was plugged into a GFCI. That took a while to track down!
CaptTom is online now   Reply With Quote
Old 18-09-2020, 12:24   #9
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Denmark (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 28,753
Re: Marinco 50 amp shore plug shorted

Quote:
Originally Posted by crayiii View Post
I started taking the end of the 50 amp shore power cable apart and found that the cord has started pulling out. Now I'm thinking there was just a partial connection being made so it may have been pulling more amps than I thought. Possible?
Absolutely.

There is a correct procedure for dealing with those Marinco plugs and sockets:

1. Carefully detach the cabling.

2. Place entire assembly in an opaque plastic bag; seal up tight.

3. Deposit in marina trash skip.

4. Purchase SmartPlug.

This is the only correct solution to any of the various failure modes of the Marinco connectors, and in fact is strongly recommended for non-failed ones as well.
__________________
"Parce que je suis heureux en mer, et peut-tre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 18-09-2020, 12:32   #10
Registered User

Join Date: May 2011
Boat: Hitchhiker, Catamaran, 40'
Posts: 984
Re: Marinco 50 amp shore plug shorted

Are these tripping breakers GFCI?
Thumbs Up is offline   Reply With Quote
Old 18-09-2020, 12:33   #11
Registered User

Join Date: Apr 2019
Posts: 266
Re: Marinco 50 amp shore plug shorted

Installed today! It will be awhile before we're in a marina to test it though.





Quote:
Originally Posted by Dockhead View Post
Absolutely.

There is a correct procedure for dealing with those Marinco plugs and sockets:

1. Carefully detach the cabling.

2. Place entire assembly in an opaque plastic bag; seal up tight.

3. Deposit in marina trash skip.

4. Purchase SmartPlug.

This is the only correct solution to any of the various failure modes of the Marinco connectors, and in fact is strongly recommended for non-failed ones as well.
Attached Thumbnails
Click image for larger version

Name:	PXL_20200918_193108766.jpg
Views:	35
Size:	292.5 KB
ID:	223685  
crayiii is offline   Reply With Quote
Old 18-09-2020, 12:47   #12
Registered User
 
Jammer's Avatar

Join Date: Jan 2010
Posts: 1,668
Re: Marinco 50 amp shore plug shorted

Quote:
Originally Posted by Dockhead View Post
There is a correct procedure for dealing with those Marinco plugs and sockets:

1. Carefully detach the cabling.

2. Place entire assembly in an opaque plastic bag; seal up tight.

3. Deposit in marina trash skip.

4. Purchase SmartPlug.

This is the only correct solution to any of the various failure modes of the Marinco connectors, and in fact is strongly recommended for non-failed ones as well.

It is my observation that all outdoor electrical connectors have a limited life. It will be interesting to see how the SmartPlugs fare when there is a larger installed base of older ones. I note that SmartPlug now have "service kits" on their website so perhaps they don't last forever either.


Is it a better mousetrap? Sure. Is it going to solve everything? You decide
Jammer is offline   Reply With Quote
Old 18-09-2020, 12:50   #13
Registered User

Join Date: Apr 2019
Posts: 266
Re: Marinco 50 amp shore plug shorted

Quote:
Originally Posted by Thumbs Up View Post
Are these tripping breakers GFCI?
These are the two breakers that trip in addition to the pedestal (this only happens at some marinas)

The first one is inside and the second one is in the engine compartment near the shore power (only the left one trips).
Attached Thumbnails
Click image for larger version

Name:	PXL_20200918_193932196.jpg
Views:	24
Size:	327.8 KB
ID:	223691   Click image for larger version

Name:	PXL_20200918_194640535.jpg
Views:	19
Size:	335.5 KB
ID:	223692  

crayiii is offline   Reply With Quote
Old 18-09-2020, 12:56   #14
Registered User

Join Date: Jan 2015
Location: SoCal
Boat: Formosa 30 ketch
Posts: 690
Re: Marinco 50 amp shore plug shorted

Quote:
Originally Posted by crayiii View Post
I started taking the end of the 50 amp shore power cable apart and found that the cord has started pulling out. Now I'm thinking there was just a partial connection being made so it may have been pulling more amps than I thought. Possible?
Back when I went through USCG ET school, current was equal to voltage divided by resistance (I=E/R), maybe Y2K changed this , but I still believe a poor connection can't cause higher current.
Since both pedestal and boat breakers, I would suspect an intermittent short on the house side of the breaker
Bill Seal is offline   Reply With Quote
Old 18-09-2020, 13:01   #15
Registered User

Join Date: Apr 2019
Posts: 266
Re: Marinco 50 amp shore plug shorted

Quote:
Originally Posted by Bill Seal View Post
Back when I went through USCG ET school, current was equal to voltage divided by resistance (I=E/R), maybe Y2K changed this , but I still believe a poor connection can't cause higher current.
Since both pedestal and boat breakers, I would suspect an intermittent short on the house side of the breaker
I've tried tracking it down but I would have thought that if it was downstream of the shore power, it would trip on generator and inverter. Planning on setting up a time with an electrician as soon as we're someplace long enough.
crayiii is offline   Reply With Quote
Reply

Tags
plug

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Shorted Battery - now Switch board Voltmeter no longer same same multimeter reading Caroline Joan Electrical: Batteries, Generators & Solar 0 23-07-2018 09:14
Two senders shorted out together on genset? msponer Engines and Propulsion Systems 7 16-10-2016 15:42
For Sale: Marinco 30 Amp Shore Power Cord $25 silverp40 Classifieds Archive 8 13-02-2014 19:52
Boiling Batteries -- Shorted Cell ? Dockhead Electrical: Batteries, Generators & Solar 15 10-01-2012 04:26
For Sale: Marinco: 50 Amp 125V SS Lock- Shore Power Inlet delmarrey Classifieds Archive 0 06-11-2010 14:07

Advertise Here


All times are GMT -7. The time now is 18:53.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.