Marinco Power Cables

[k1vsk]

If you routinely connect/disconnect with the power on, internal arching inevitably can occur causing the burn marks in your picture. As you can imagine, the instantaneous connection/disconnect, particularly if the conenctor pins are dirty, can arch. I don't know if you do this but I've seen many people do it and, correctly or not, I attributed their failed connectors to that process.
It's always a good habit to first shut down the breaker before disconnecting.

[JohnRPollard]

Originally Posted by k1vsk

If you routinely connect/disconnect with the power on, internal arching inevitably can occur causing the burn marks in your picture. As you can imagine, the instantaneous connection/disconnect, particularly if the conenctor pins are dirty, can arch. I don't know if you do this but I've seen many people do it and, correctly or not, I attributed their failed connectors to that process.
It's always a good habit to first shut down the breaker before disconnecting.

K1,

When you say "shut down the breaker", are you referring to the shore power breaker in the boat, or out on the dock? I always shut down the breaker in the boat, but have never shut down the breaker at the dock. In all honestly, it never occurred to me that I should do that...

[k1vsk]

Originally Posted by JohnRPollard

K1,

When you say "shut down the breaker", are you referring to the shore power breaker in the boat, or out on the dock? I always shut down the breaker in the boat, but have never shut down the breaker at the dock. In all honestly, it never occurred to me that I should do that...

I was referring to the breaker on the dock - the supply breaker

[JohnRPollard]

Originally Posted by k1vsk

I was referring to the breaker on the dock - the supply breaker

Roger that. Thanks, I'll add it to our routine.

[Sreya]

I too had one go like that and I wondered if I had been neggligent in making sure that the twist-lock was all the way over and then tightened the retainer ring.
It is easy to become non chalant about some of these things
A thought
George

[camaraderie]

Shutting down the dockside breaker is something I always do before plugging in a transient boat. Then I ask the captain if it is ok to turn it on.
Surprising how many look at me like they've never considered that question before!

[xort]

K1
Does it really matter if the breaker on shore is off... if the breaker at the boat is off and there is no flow of power?

I do think this is a combination of things.
Poor connection due to not twisting the connector on all the way.
Wiggling the cable and causing arcing.
Plugging and unplugging while power is flowing.
Salt & other stuff causing corrosion and poor connection.

This came up on another list and Hubbell was mentioned as using a different method of connecting the lugs to the wires. Sorry I don't recall the differences.

Rings can be forced on to the plugs, I've done it. I don't recall ever seeing a dockside recepticle with threads for screwing the ring to.

[SteveInMD]

You are right that if the breaker on the boat is off there will be no current flow in the cord. However, I would turn off the dock side breaker before unplugging, just because working near salt water around a live 30 amp cord seem like a bad idea to me.

If you don't bother with turning off the main breaker on the boat either, you could get some arcing when you connect or disconnect.

[Sapperwhite]

Originally Posted by k1vsk

.....
It's always a good habit to first shut down the breaker before disconnecting.

Absolutly (dockside pedestal breaker). Aside from arcing when you plug a live cord into the boats receptical, there are personel safety issues here (as some others have noted). Anyone else ever concider they are holding a live line while standing near a whole lot of water? It is not the voltage that will kill you (well, not 120v), but the amperage. 30 amps, let alone 50 amps, is way more than enough to disrupt your hearts rhythm.

If you are holding the cord while wet or standing in water, and the electricity seeks ground through you, you can be injured or killed as it passes through your heart. Your skin does act like a faraday cage for your internals, but that can be overcome. Otherwise, everyone who ever got zapped with even low amps would go into cardiac arrest (which doesn't happen).

Long story short:
When coming in; breaker at the pedestal off and breaker onboard off, plug in on the boat, then plug in at pedestal, breaker on at the pedestal, then breaker on the boat on.

[k1vsk]

Originally Posted by SteveInMD

You are right that if the breaker on the boat is off there will be no current flow in the cord. .

WRONG!
We're not talking about current flowing on the cable. That has absolutely NOTHING to do with it.

The thread is about the cable ends arching thereby destroying the pins and the cable which occurs every time you connect/disconnect to a live plug..

If you don't believe me, do a simple experiment at home by plugging in a lamp (while shut off) to a socket slowly - you'll see the arch at the junction.

Believe it or not - your choice and I'm sure Marinco thanks you for not believing.