Arcing in 30 amp shore power cord? (Picture)

[CSY Man]

Originally Posted by Sailmonkey

Whoever sent that message to you must be unaware that most boats with 30a shore connections and any load greater than 18-20 amps have melted connections.

That, or he had a bad day...

[Greg theHijacke]

First place to look is at the terminals on the inside of the socket on the boat.
It will almost certainly be a loose cable terminal screw or frayed copper wire connection. Go straight to the socket and check it out.
I speak from experience as that is what happened to me.

[Manateeman]

We are not sure we would use any paste that contains metal particles. A number of anti oxidation pastes were developed for aluminum wire. Some electricians use them on copper to copper connections. We use Tef-Gel. Sometimes Boshield.
Often we just pull stuff apart and clean again if we see the green stuff.
We’ve seen heavy salt spray hit dock pedestals hour after hour. They don’t use anything to prevent corrosion and many haven’t got a clue about grounds.
We noticed it seemed the worse burning was the safety ground connection on your plug. We’d examine the boat very carefully.
Mark

[goboatingnow]

Originally Posted by CSY Man

Hello from Florida:
Plugged in my 30 amp cord to run the 10,000 BTU A/C: Strong smell of burnt something.
Disconnected the cord and noticed black soot marks on the female end.
Cleaned the male contacts (They were already clean, no corrosion, but black from the arcing)

Different day, different marina AND different cord, same result: Arching and burned smell.
What is going on?
(No breakers popped on the boat or on the dock pedestals, the A/C was working normally.)

A short in the vessel's 110 volt system? (If so, breakers should have popped)

awful units , Ive rewired three this year due to arcing in the plug , Im going to change all mine to the EN 60309-2 3 pin round "blue" plugs and sockets , these never give arcing issues , that Marincio units isnt fit for purposes in my view

[CSY Man]

Originally Posted by Greg theHijacke

First place to look is at the terminals on the inside of the socket on the boat.
It will almost certainly be a loose cable terminal screw or frayed copper wire connection. Go straight to the socket and check it out.
I speak from experience as that is what happened to me.

I removed the inlet and found one of the contacts was lose and arced on the inside as well. (Not sure if the heat made it come lose, if it was pushed in by force when inserting the plug numerous times over 21 years.

There was mot much if any corrosion either side of the inlet as it was installed in a very protected place inside a coaming.

Picture should rotate 90 degrees clock wise.

[CSY Man]

I meant to take a picture of the removed inlet but forgot..

In the meantime I am selling the boat, bought a new inlet for the buyer, he can hire a marine electrician to install it, or do it himself.
The boat was surveyed Friday, the surveyor recommended a smart plug and also mentioned that new code requires a breaker on the circuit within 10 feet of the shore power inlet. (A special dual purpose breaker, forgot what it is called.)
If keeping the boat I will certainly upgrade the shore power side with the fancy breaker and the smart plug and re-wire system from inlet to AC panel.

[thesaltytar]

Originally Posted by CSY Man

... I am selling the boat...

That escalated quickly...! [emoji3]

[CSY Man]

Originally Posted by thesaltytar

That escalated quickly...! [emoji3]

Yeah, we moved recently and I realized it is not the right boat for our new cruising grounds.
Fort Lauderdale was great with The Bahamas next door and the Florida Keys to the South.
Now we are in Palm Coast and can use a Center Console T-Top Bay Boat to cruise up and down the ICW. We will instead fly to Nassau and rent a sailboat there to cruise the Exuma Islands.
All good.

[79Endeavour32]

The issue is stress on the cable transferred to the female end at the boat. Lay a portion of the cable on the deck with no stress whatsoever. Tie it off securely to boat. You will not have any more burned cables unless lightning hits the dock power system. I worked gunboat river security for department of Army for nine years, and never had a burned cable as long as the stress point was isolated.

[Sailmonkey]

Originally Posted by 79Endeavour32

The issue is stress on the cable transferred to the female end at the boat. Lay a portion of the cable on the deck with no stress whatsoever. Tie it off securely to boat. You will not have any more burned cables unless lightning hits the dock power system. I worked gunboat river security for department of Army for nine years, and never had a burned cable as long as the stress point was isolated.

What was the current draw on the shore cord and what was the ampacity of the connector?

Twist lock 30a shore cord ends will get hot with a sustained current over roughly 20a.

[CSY Man]

Originally Posted by Sailmonkey

What was the current draw on the shore cord and what was the ampacity of the connector?

Twist lock 30a shore cord ends will get hot with a sustained current over roughly 20a.

The current draw was about 15 amps, running 10,000 btu air condition.
Ampacity of the connector? Cable and connectors rated for 30 amps.
In other words, nothing was overloaded, probable cause was probably age and too many guys using too my force to push and twist over the years until one of the connectors came lose and a bad connection caused the arcing.

The issue is stress on the cable transferred to the female end at the boat.

Not much stress on the cable, but it can't be out
-ruled of course.

[Dockhead]

Originally Posted by goboatingnow

awful units , Ive rewired three this year due to arcing in the plug , Im going to change all mine to the EN 60309-2 3 pin round "blue" plugs and sockets , these never give arcing issues , that Marincio units isnt fit for purposes in my view

The blue ones are good, but the SmartPlugs are the gold standard.

The Marinco ones should be banned. Shockingly bad design; inherently dangerous