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.
You might consider turning on the breaker on the pedestal last instead of the one on the boat because everytime a breaker is turned on or off under load there is some degradation of the contact points. I would prefer to wear the marinas equipment more than mine.
To those who have had problems with the Marinco 30 amp cord ends...What is the actual measured load that you are consuming? Are you guys really using 30 amps?
Could it be that Marinco/Hubbell has substituted a less conductive, and less expensive, metal in their cord ends? Considering the skyrocketing cost of metals around the world that would not be surprising.
I was referring to the post immediately above my post by xort. I'm not "WRONG!" in the slightest bit. If the main breaker is off at the boat and on at the dock there will be no arcing when the cord is unplugged. However it's still not a good idea due to safety.
Quote:
Originally Posted by k1vsk
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.
Farcry,
I got you. It's true that when you throw you boats AC main breaker you are creating an arc inside your breaker, not the pedestal breaker. I don't ever throw the AC main with other AC breakers in the on postition, so the load is minimal. I my only load at that point is the not loaded AC panel.
******
Opening just the boats main AC breaker only isolates the AC panel, and everything that it serves. The wiring between the boats AC main breaker and the shorepower cord recepticle is still hot if the pedestal breaker is closed (or "On").
See this diagram I just found online:
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Dictated, but not read.
Last edited by Sapperwhite; 09-11-2008 at 11:46 AM.
I was referring to the post immediately above my post by xort. I'm not "WRONG!" in the slightest bit. If the main breaker is off at the boat and on at the dock there will be no arcing when the cord is unplugged. However it's still not a good idea due to safety.
Ah, disregard my last post then. I was confused also. I'll leave it up though for any other members who might be scratching their heads on this issue.
Here is a "grown up" version of what happens when you just disconnect power without opening the breakers on both sides first. A 120v arc is much smaller, here is 500Kv.
We were talking about current flowing though cables. It was mentioned that disconnecting a cable with current flowing deteriorates the cables end (it causes pitting and carbon build up) due the arcing.
There must be a problem with your lamp, because mine certainly doesn't arc at all. No current = no arc. It doesn't matter which end of the circuit is open as long as it's open somewhere no current will flow. Does just a little current flow when you plug in an shore cord with the boat breaker off? No.
Quote:
Originally Posted by k1vsk
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.
If there is a load on one end of a power cable then you will get acring because current is flowing. If nothing is present to put a load be it a lightbulb, short, or whatever nothing will ever happen.
In your little movie current. is flowing, therfore the arc. It has to have somewhere to go to arc.
If the pedestal breaker is closed, and the cord is plugged in, there is current present. you are connecting a live line to a dead bus. The first video shows what happens when you disconnect with both sides live. Here is a video of what happens when you close a live line onto a dead bus (No load at all, just the conductor section). This a large scale version of what happens when you energize a dead bus with absolutly no load on it.
this is the reason the breakers are closed last, so the arc is contained within the breaker.
Edit:
Quote:
If nothing is present to put a load be it a lightbulb, short, or whatever nothing will ever happen.
live line dead bus means that the dead bus will be the load, you are energizing with the cord (live line provided the pedestal breaker is closed) wiring between your recepticle and your AC main breaker (the dead bus)
__________________
Dictated, but not read.
Last edited by Sapperwhite; 09-11-2008 at 01:07 PM.
I'll stick with my statement. If you have no load on the shore cord, such as the main breaker on the boat being off, it wont arc. The video is not an accurate representation of what's happening on the dock because there's voltage threshold effect that we don't meet in the dock example.
First, this is in fresh water. Obviously it is happening in salt water too - but the examples I am using are all fresh.
Second, there was NO corrosion on the terminals of the receptacle. I do not know about inside the cords as that is not visible on a sealed cord. Of even more interest, on Dad's cord that burnt up, it was where a female and male Marinco cord hooked together - and not the boat terminal.
Third, I have been boating a long time. I have never seen this happening until recently.
Fourth, the point has been made about improper locking/unlocking. It has also been suggested that the rings were not fully screwed in. In ALL cases, I have personally screwed in the rings. Not an issue for me. On dad's boat, I guarantee you that it was screwed in as it was male-female cord connections. I do not know on the other 400 - but as he is a long term cruiser, I would have to assume he also screwed his in... but again, I am not sure about that. Also, since I always plug in the cords, I can guarantee you that they were always completely locked.
Fifth, I won't say that I have never forgotten to flip off our power... I am sure it has happened. However, it would be by far the exception than the rule. That being the case, it seems unlikely to me that flipping on/off the power is the culprit.
Let us not forget that these cords are made to be removed and replugged in. That is their design. They are also designed, supposedly, for the marine environment. If it says 30A cord on it, I expect that to mean that I can pull a SOLID 30a without overheating. In theory, they should not ever be subject to more than 30a for very long. In order for them to exceed 30a, you would need a failure of: 1) the Main breaker at the dock (30a), 2) the main breaker a the boat (30a), the main breaker at the panel (30a). It seems HIGLY unlikely that we would have that many failures on that many different boats with that many circuits. It should also be noted that my second cord that failed was plugged into a completely different receptacle with different breakers at the dock and boat.
At this point, I am beginning to feel the cord is suspect. I am concerned they have changed something in their manufacturing in the last few years. That is why I am probing many of you on this. Also, I want to eliminate the likelihood that it is dock, marina, or boat specific.
- CD
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Snapper ya got it all wrong
