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Old 27-11-2007, 15:38   #1
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Burnt terminal on 30 amp power cord

Is it safe or recommended to replace a three prong end of a 30 amp power cord with a replacement. It seems quite wasteful to throw away a whole 50 foot power cord because of a scorched end. I found a replacement Turnlock Locking Plug at Lowe’s. It is 30 amp 125 VAC. It doesn’t say marine grade or water proof but the fellow at the store said it would be fine. I haven’t seen anything from Marinco at West Marine.

The problem occurred when I connected to a marina that had bad power. They told me that AFTER I plugged in!

Thanks in advance.
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Old 27-11-2007, 15:56   #2
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Yes.
Any 30A 120VAC 2P 3W twist-lock male cord cap (NEMA type L5-30P) will do, 'though a nylon body & weather-proof sleeve are recommended.
To install a new plug, cut the cord back past any damage, and ensure the conductors are clean & bright, and the insulation is undamaged.
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Old 27-11-2007, 15:59   #3
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You don't have to throw away that cord.

30A 125V Locking Connector with 103RN Weatherproof Cover

If that is not exactly what you were looking for then they do have something that will work.
Marinco Search Results[fsl]Plugs[fsl]Accessories

I get mine at West Marine. If you are looking for less costly then try Defender Industries online.

Don't go the hardware store route, they may be using ferrous metals which will eventually rust out...even sitting on a marina dock. Prolong its life by coating the connectors wires, screws and contacts with some silicone grease. There is no such thing as a waterproof dock connector. Eventually the salt air will get to it.
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Old 27-11-2007, 17:03   #4
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Cathy,

As Gord says, just cut the old cord back enough so you have clean, bright wires.

Be especially careful in wiring the new plug to be sure the connections are correct. You definitely don't want to reverse the hot and neutral, for example. Black is hot; white is neutral. Green is ground.

I would use only marine-grade connectors: Marinco or, better, Hubbell. You can find them online or in any marine store.

Bill
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Old 27-11-2007, 17:54   #5
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Thank You!

Gord, David, and Bill

Wow, what fast service! Thank you so much for your advice! I am off to return what I bought and get a marine grade product instead.

Much appreciated!
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Old 27-11-2007, 20:50   #6
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Cathy, Bad power will not cause what has happend. This fault is most likely a case of a poor connection. What ever the plug connects to, make sure the pins are clean. dirty contacts will cause a poor contact and thus will end up heating and burning up the contacts.
Do NOT ATTEMPT to clean the contacts if the contacts you are cleaning are live.
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Old 27-11-2007, 21:03   #7
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A tip if you plan to do any work with AC wiring - doesn't matter if it's your boat, house, whatever. Do yourself a favor and buy a parasitic voltage detector. This cheap (~$15) device emits a tone and flashes a light if any wire it's next to has live 110/220AC.

After cutting into a live 220 wire many years ago and getting lucky that nothing bad happened, I went out and bought one of these. It could save your life, and it would have saved me from doing what I did - I turned off the circuit I planned to work on, but I cut the wrong piece of romex which was energized and a different circuit.
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Old 28-11-2007, 01:44   #8
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The most usual culprit in burnt Cord Connectors is disconnecting (or connecting) them under load.
Prior to connecting or disconnecting the shore power cord, always turn off the shore side supply circuit breaker, and the boat side master A/C breaker/switch.

The next most common fault is dirty, corroded, or loose terminal blades.
Other than a lightning strike, there’s nothing else (I can think of) that will cause burnt plugs.

Prior to plugging in your shore power cord, check both your male cord cap, and the marina’s female receptacle, for visible damage.

Once plugged in (boat side, then shore side), turn on the shore power breaker; and check your reverse polarity indicator* (actually, it’s preferable to test the shore power polarity, prior to plugging in).
Only then, turn on your boat’s A/C master switch/breaker, and then any loads you wish to use (1 at a time).

* Reverse Polarity:
Goto:
http://www.cruisersforum.com/gallery...age.php?i=1717
And: Reverse Polarity (AC)
And: Reverse Polarity Light
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Old 01-12-2007, 22:52   #9
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The most common cause of burnt out plugs I see are ones that aren't locked in
and......
trying to put too many Amps through......(I don't know if that is the correct electrical term) but it basically trying to run too much stuff at one time
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Old 01-12-2007, 23:25   #10
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And,

one thing that hasn't been mentioned yet! If this outlet is on the dock or shore, a common problem is water getting sprayed on the connection or being exposed to the rain, that can cause a shorting/overheating of the terminals!

And make sure the outlet that your plugging into is in good shape. If not the dock master should be notified.
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Old 02-12-2007, 04:18   #11
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Quote:
Originally Posted by Chief Engineer View Post
The most common cause of burnt out plugs I see are ones that aren't locked in
and......
trying to put too many Amps through......(I don't know if that is the correct electrical term) but it basically trying to run too much stuff at one time
It should be impossible to “put too many Amps through” (overload) the shore power circuit.

Every authority (code) requires that the shore power receptacle be protected by an appropriate Over-Current Protective Device* (Fuse or Circuit Breaker); sized to match the wiring & dock receptacle.

Every boat should also have a main disconnect & overcurrent device (disconnect switches & fuse, or Circuit Breaker).

* An OCPD protects equipment by opening when it detects an overload, short-circuit or ground fault.

Hence, a 30Amp shore power outlet (and it's branch wiring) will be protected by a 30A Fuse/Breaker, preventing more than a 30A load.
Likewise, your Boat’s 30A OCPD will also prevent an overload.

Marinco® has an excellent publication: “Boater’s Guide to AC Electrical Systems” at:
http://www.guestindustrial.com/docs/guides/Boater'sGuidetoACElectrical.pdf
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Old 02-12-2007, 17:09   #12
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"It should be impossible to “put too many Amps through” (overload) the shore power circuit."

Gord,
You obviously haven't landed at Marina Nuevo Vallarta in Puerto Vallarta. Maybe they've fixed it since I cruised in the '90's, but back then it was a cheap seat marina where lots of broken dreams sailors ended up.

The wiring was a live bare wire do it yourself affair as was how you moored.

To get shorepower, you gingerly found out which wire was the hot one
(Color coding? wee don' need no steenkin' color coding!) then you attached your own system of connecting your shorepower cord to it. Some people used alligator clip leads!

Lots of 20' finger piers with not a lot of boats so people tied diagonally in 2 slips, or across the ends of 3 fingers etc.

As you may imagine, there were boats piled high with junk on the decks and there was a swap meet every day. As you may also imagine, there were almost no women in the marina.

Steve B.
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Old 02-12-2007, 17:33   #13
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The bad connection

If you use factory manufactured marine shore power cords and find that one or more contacts have overheated causing melting of the insulation and destruction of the contacts the problem is USUALLY a poor connection(s) either where the boat wiring attaches to the inlet or a poor connection(s) where the shore power wires connect to the outlet where you plug in.

It is relatively easy to periodically check the ship's side of the wiring and apply an anti-oxidant to the wire termination yet it is usually a surrepticious project to throw the shore breaker and get into the shore box to do the same (and more dangerous, especially if you don't know what your are doing). If the shore wires are not checked you will always be at the mercy of a poor connection there ruining your expensive shore power cord.
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Old 03-12-2007, 03:22   #14
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Quote:
Originally Posted by senormechanico View Post
... Gord,You obviously haven't landed at Marina Nuevo Vallarta in Puerto Vallarta. Maybe they've fixed it since I cruised in the '90's, but back then it was a cheap seat marina where lots of broken dreams sailors ended up.

The wiring was a live bare wire do it yourself affair as was how you moored.

To get shorepower, you gingerly found out which wire was the hot one
(Color coding? wee don' need no steenkin' color coding!) then you attached your own system of connecting your shorepower cord to it. Some people used alligator clip leads ...
Steve B.
It seems that the, obviously deplorable, conditions you describe at Marina Nuevo Vallarta, shouldn’t be considered representative of “the most common” cause of shore power cord failures. You’ve described “exceptionally” sub-standard, and potentially deadly conditions.
Those who choose to jury rig their own connections to such facilities should know what they are doing, and the implications of what they are doing.

The burn marks are a sign of arcing, either within the receptacle or within the connector, or between the two (see Rick's "Bad Connection").

See also: “Shore Power Interrupted ~ by Nigel Cauder (PBB)
Professional BoatBuilder - April 2006/May 2006

and see the sidebar “A closer look at the Cord”, on page 62.
Professional BoatBuilder - April 2006/May 2006

And:
“AC Electrical Safety” ~ by Terry Johnson
http://seagrant.uaf.edu/bookstore/bo...cal-safety.pdf

***

This plug was wired by the boat owner. The pink wire is a 120v ungrounded conductor (hot wire). He attached it where the ground wire was supposed to go. Note how the green ground wire was taped off and unused.
He unknowingly electrified the metal hull of his houseboat which ultimately led to the electric-shock drowning deaths of his wife and daughter.
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Old 03-12-2007, 12:44   #15
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Looking at how that green wire is taped off...there is a safer way of doing it. It's not so much that the wire might be carrying current, it's more likely that the wire could hit the hot and arc, starting a fire or really screw up a piece of equipment or cause intermittent voltage drops that you will never find. Yes, I know thats the ground and it should be wired in.

Whenever I have a bare end of wire like that, I put a crimp butt connector on the end instead of taping it off. Doing this is much more secure than electrical tape. I then pinch down the unused end of the plastic insulation on the butt connector. With any kind of oil or high heat, electrical tape gets mushy and becomes worthless. I try my best to avoid using it onboard. There are plenty of times when you are provided with a bare end of wire that you do not need to connect to anything, but still has the potential to screw things up if it touches another wire or something else.
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