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09-03-2016, 07:41 AM
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#1
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Senior Member
City: Blaine
Vessel Name: Slow Bells
Vessel Model: Marine Trader 38
Join Date: Nov 2013
Posts: 327
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shore power cord problems
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09-03-2016, 07:57 AM
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#2
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Guru
City: North Charleston, SC
Join Date: Sep 2010
Posts: 4,870
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The black carbon deposits are a sign of arcing (sparks). Both your cord and the inlet are beyond repair and should be replaced. Replacing one won't work, the other one will quickly ruin the new one.
How to prevent it? To start with, always, without fail, turn off the breaker on the dock pedestal before connecting or disconnecting the cord. If there's no breaker on the dock pedestal, turn off the main breaker on your boat before connecting or disconnecting the cord. Unplugging the cord when electricity is flowing is sure to generate an arc and that causes what you see.
Sometimes we see this damage on the male end of the cord and that's caused by a faulty outlet on the dock pedestal. That's more difficult to deal with because it belongs to the marina. Use a different outlet or ask them to replace it.
Other things to do: Don't drop the ends of the cord in the water, especially salt water. Don't leave them out in the rain when not in use.
Applying a coat of dielectric grease to the pins and sockets is a good maintenance procedure as it will shield the contacts from corrosion but still allow electrical contact. Dielectric grease is an insulator but the action of plugging in the plug wipes the grease from the actual contact surfaces.
Screwing on the ring helps hold the plug steady so it doesn't wiggle and loosen. Strapping the cord to the boat a foot or two from the plug also helps to remove strain and movement.
In the end, you should plan on replacing these things every several years.
I've never seen a surge protector on a boat or one in a catalog intended for a boat. I wouldn't worry about it.
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09-03-2016, 08:01 AM
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#3
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Valued Technical Contributor
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,784
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That damage has nothing to do with surge.
The traditional twist lock 30 amp connector has a number of deficiencies in marine use: connector comes loose which reduces contact, contacts are too small to carry full current continuously, salt environment makes connections less reliable.
One solution is the Smartplug, a positive locking, enclosed connector with more contact area. See Home -.
Another is Marinco's EEL connector. See EEL Cordset, 30A 125V, Yellow, 50' | Marinco
David
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09-03-2016, 08:22 AM
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#5
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Senior Member
City: Blaine
Vessel Name: Slow Bells
Vessel Model: Marine Trader 38
Join Date: Nov 2013
Posts: 327
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Quote:
Originally Posted by WesK
Applying a coat of dielectric grease to the pins and sockets is a good maintenance procedure as it will shield the contacts from corrosion but still allow electrical contact. Dielectric grease is an insulator but the action of plugging in the plug wipes the grease from the actual contact surfaces.
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How often do you apply this grease?
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09-03-2016, 08:28 AM
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#6
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Guru
City: New England and Canada to Florida
Vessel Name: Tadhana
Vessel Model: Helmsman 38 Pilothouse
Join Date: Jul 2011
Posts: 596
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This is caused by resistance in the electrical connection while trying to draw a heavy load. Resistance can be caused by corrosion, arcing and loose wire connections. I recorded temperatures this summer on my standard 30 amp connection saw a 30 degree temp rise above ambient when carrying a 27 amp load for 30 minutes. Replaced the standard Marinco hull inlet and still had a 19 degree temp rise. Ordered a smart plug inlet $$. Replaced that inlet with a smart plug and had a 3.5 degree temp rise. We cruise full time and have been in about 30 different slips since the first of this year. About 80% of the time the power post breaker is on when we go to connect our cords. Naturally I turn it off before connecting, but this tells me that 80% of the time people are "hot plugging." That leads to arcing, arcing creates burns which have high resistance and that causes heat. I am also amazed at how many people do not close the cover on the hull inlet when under way. that allows salt air/spray etc lead to corrosion. Also am always surprised how few people use the locking ring to seal the 30 amp hull inlet: if you don't use the locking ring water gets in and creates corrosion. I use electric conductive pate on my plug spades if I am forced to plug into a suspect dock power pedestal. I have written about this for SAIL and Chesapeake Bay Magazine. Have a follow up article on the Smart Plug performance due out this winter.
https://dl.dropboxusercontent.com/u/...ng%20along.pdf
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09-03-2016, 08:33 AM
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#7
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Senior Member
City: Marathon
Vessel Name: silver gift
Vessel Model: 45 jefferson
Join Date: Nov 2013
Posts: 291
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Have found that this problem is caused by using to many heavy amp devices,a/c and water heater on one circuit. Would replace both ends and try to regulate your loads so you don't draw too many amps. The ground wire cannot take the load of two heavy devices. Since watching my loads I have had no problems since.
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09-03-2016, 08:44 AM
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#8
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Senior Member
City: Blaine
Vessel Name: Slow Bells
Vessel Model: Marine Trader 38
Join Date: Nov 2013
Posts: 327
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Quote:
Originally Posted by Deckape
Have found that this problem is caused by using to many heavy amp devices,a/c and water heater on one circuit. Would replace both ends and try to regulate your loads so you don't draw too many amps. The ground wire cannot take the load of two heavy devices. Since watching my loads I have had no problems since.
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That plug is used exclusively for the air conditioner (which died 3 weeks ago) so there is no way to regulate the amperage draw through that circuit.
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09-03-2016, 08:53 AM
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#9
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Guru
City: Stuart FL
Vessel Name: Lucky Lucky
Vessel Model: Pacific Mariner 65
Join Date: Aug 2013
Posts: 2,760
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Is there any information comparing the EEL plug to the Smart Plug? Casual observation shows more EEL Plugs around our local docks than Smart Plugs. They seem easier to use as you don't need to replace the boat or power post plugs. Thoughts?
__________________
Howard
Lucky Lucky
Stuart, FL
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09-03-2016, 09:40 AM
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#10
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Guru
City: San Diego
Vessel Name: Circuit Breaker
Vessel Model: 2021..22' Duffy Cuddy cabin
Join Date: Oct 2007
Posts: 6,691
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Quote:
Originally Posted by djmarchand
One solution is the Smartplug, a positive locking, enclosed connector with more contact area. See Home -.
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Works for me!
__________________
Done with diesel power boats! Have fallen in love with all electric!
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09-03-2016, 09:42 AM
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#11
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Guru
City: San Diego
Vessel Name: Circuit Breaker
Vessel Model: 2021..22' Duffy Cuddy cabin
Join Date: Oct 2007
Posts: 6,691
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Note the "thermostat" feature
__________________
Done with diesel power boats! Have fallen in love with all electric!
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09-03-2016, 09:44 AM
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#12
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Guru
City: Sarasota/Ft. Lauderdale
Join Date: Apr 2014
Posts: 5,438
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Quote:
Originally Posted by seattleboatguy
That plug is used exclusively for the air conditioner (which died 3 weeks ago) so there is no way to regulate the amperage draw through that circuit.
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Why did the A/C die? Could it have been pulling a very high amp load before it died?
After you replace the cord (30a cords are cheap) and boat side receptacle, you need to meter the loads on that cord. If it's consistently at or over 80% of the 30a max load rating of you current cord, you should consider changing over to a 50a 250/125v cord system.
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09-03-2016, 09:47 AM
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#13
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Guru
City: Sarasota/Ft. Lauderdale
Join Date: Apr 2014
Posts: 5,438
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If you stick with the 30a cord, unplug both ends and check them regularly and spray all the contact points with Boeshield or something like it as needed. Or at least a few times a year.
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09-03-2016, 10:02 AM
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#14
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Guru
City: Powell River, BC
Vessel Name: Northern Spy
Vessel Model: Nordic Tug 26
Join Date: Feb 2012
Posts: 4,075
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Quote:
Originally Posted by hmason
Is there any information comparing the EEL plug to the Smart Plug? Casual observation shows more EEL Plugs around our local docks than Smart Plugs. They seem easier to use as you don't need to replace the boat or power post plugs. Thoughts?
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The EEL plug is certainly easier to use than the standard threaded ring plug, but it suffers from the same limited contact area of a NEMA L5-30 connection. See attached.
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09-03-2016, 10:04 AM
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#15
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Guru
City: New England and Canada to Florida
Vessel Name: Tadhana
Vessel Model: Helmsman 38 Pilothouse
Join Date: Jul 2011
Posts: 596
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Quote:
Originally Posted by hmason
Is there any information comparing the EEL plug to the Smart Plug? Casual observation shows more EEL Plugs around our local docks than Smart Plugs. They seem easier to use as you don't need to replace the boat or power post plugs. Thoughts?
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The Eel plug has exactly the same "Guts" as the standards 30 amp hull inlet and cord end. So far as I can tell, his design was simply a way to make it easier for people to lock the plug to the hull inlet. It has no improved load carrying ability.
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09-03-2016, 10:06 AM
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#16
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Senior Member
City: Blaine
Vessel Name: Slow Bells
Vessel Model: Marine Trader 38
Join Date: Nov 2013
Posts: 327
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Quote:
Originally Posted by Capt.Bill11
Why did the A/C die? Could it have been pulling a very high amp load before it died?
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Yes, that is very possible. The a/c tech who examined the dead Lunaire air conditioner said that the compressor was shorting to ground. There were also some scary melting wires in back of the control panel. It was not a happy a/c. I now have a new Ocean Breeze a/c sitting on the floor of my main cabin, waiting for me to install it this weekend.
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09-03-2016, 10:08 AM
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#17
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Senior Member
City: Blaine
Vessel Name: Slow Bells
Vessel Model: Marine Trader 38
Join Date: Nov 2013
Posts: 327
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Quote:
Originally Posted by Capt.Bill11
If you stick with the 30a cord, unplug both ends and check them regularly and spray all the contact points with Boeshield or something like it as needed. Or at least a few times a year.
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So, inspect the shore power connector and re-apply the spray twice a year. Is that correct?
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09-03-2016, 10:15 AM
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#18
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Guru
City: Fort Myers, FL... Summers in the Great Lakes
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 12,834
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Quote:
Originally Posted by seattleboatguy
Yes, that is very possible. The a/c tech who examined the dead Lunaire air conditioner said that the compressor was shorting to ground. There were also some scary melting wires in back of the control panel. It was not a happy a/c. I now have a new Ocean Breeze a/c sitting on the floor of my main cabin, waiting for me to install it this weekend.
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Before you install the new AC, You really need to check and maybe replace wire and breaker between the dead 30 amp receptacle and the AC unit. If you cooked the receptacle and power wires within the AC, good chance there is overload damage elsewhere.
Ted
__________________
Blog: mvslowhand.com
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09-03-2016, 10:22 AM
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#19
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Guru
City: Everett Wa
Vessel Name: Eagle
Vessel Model: Roughwater 58 pilot house
Join Date: Oct 2007
Posts: 2,919
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Quote:
Originally Posted by seattleboatguy
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Newer boats have a breaker right after next to the boats shore power out let between the out let and the main panel selector switch to protect the cord and out let. Older boats do not have the breaker. We updated our electrical with a smart plug for addition safety.
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09-03-2016, 10:27 AM
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#20
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Guru
City: New England and Canada to Florida
Vessel Name: Tadhana
Vessel Model: Helmsman 38 Pilothouse
Join Date: Jul 2011
Posts: 596
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Quote:
Originally Posted by Capt.Bill11
If you stick with the 30a cord, unplug both ends and check them regularly and spray all the contact points with Boeshield or something like it as needed. Or at least a few times a year.
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This is good advice, and we consider it standard practice. If you cruise a lot you will sometimes get to marinas with questionable dock receptacles. Eventually one of them will overheat and damage your cord end despite the care you take of your own cord.
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