Marinco Power Cables

[SteveInMD]

Here's a device that lets you combine two legs...

West Marine: Smart Y 50 Shore Power Adapter Product Display

[sailingdog]

AFAIK, there isn't a regulation requiring a double breaker, but in a marine situation, it would be prudent.

Originally Posted by FarCry

SD,
Where could I find a regulation requiring a breaker to disconnect both hot and neutral lines for shore power connections in a marina? I am looking in the 2008 NEC 555.17 (A) and do not see it. 555.17 Disconnecting Means for Shore Power Connections (A) Type-The disconnecting means shall consist of a circuit breaker, switch, or both, and shall be properly identified as to which receptacle it controls.

If your neighbor's boat has a problem and is feeding AC from the hot line to the neutral line, and your boat's shore power outlet is wired in parallel to his, then his feeding AC into the neutral line will be showing up on your boat.

I am also trying to comprehend how, if my neighbors boat was wired with reverse polarity, it could make my neutral hot. A drawing would help. Maybe I am not awake yet.

[Cruisingdad]

There are two 120v inputs. One runs Air conditioners, one runs everything else. There is no power share inside the boat.

- CD

[SEMIJim]

Originally Posted by SteveInMD

Here's a device that lets you combine two legs...

West Marine: Smart Y 50 Shore Power Adapter Product Display

I don't know for sure, as, with this, we're starting to get outside my level of knowledge/expertise/understanding, but that product does not strike me as a Particularly Good Idea. ISTM its operation is predicated on the assumption that any two receptacles are each one-half of a split-phase feed. While certainly common (at least in the U.S.): I don't know as it's necessarily true.

Jim

[LarryandSusanMacDonald]

SemiJim said:

You beat me to it . A couple of nits, tho: Not really "opposite phases," per se, but split-phase. (Opposite sides of the same center-tapped phase.) The two "legs" are properly designated "L1" and "L2," have 240VAC across them, and 120VAC to the common neutral, which is the center-tap. Secondly: The grounds, like the neutrals, will be common at the distribution panel. I don't know as they're required to be physically connected to earth ground at the receptacle end. I think not, but I am neither a licensed electrician, nor do I play one on TV .

None of the breakers at the marina where I work break the neutral as well as hot. It isn't code. So it's probably not done anywhere.

What is code though is that the ground cannot be common with the neutral at the distribution (breaker) box if the box is located on the dock. The neutral and ground MUST run separately all the way to the shore. That is code.

The "opposite phase" vs. "split phase" is just semantics. Technically, you are probably correct, however, in my meager mind it means the same thing.

In re.: the neutral burning up, I'm not sure why it is, but I have seen scores of burns on shore power outlets and shore power cords. The vast majority are on the neutral. We've had many discussions here at the Yard where I work, and no one can seem to come up with a reasonable idea why.

The most likely is, that the neutral is often on top when the plug is in, and the weight of the cord causes it to sag and it therefore isn't making a solid connection. That said, I have also seen the neutral wire burned in the meter on many occasions when the cord and the receptacle are intact and the hot is just fine. So it remains a mystery. I believe the Bermuda Triangle may be involved. But then again, I'll believe almost anything, except scepticism.

[SteveInMD]

But it supposedly intelligently verifies the phases are opposite. Isn't that the important part here?

Originally Posted by SEMIJim

I don't know for sure, as, with this, we're starting to get outside my level of knowledge/expertise/understanding, but that product does not strike me as a Particularly Good Idea. ISTM its operation is predicated on the assumption that any two receptacles are each one-half of a split-phase feed. While certainly common (at least in the U.S.): I don't know as it's necessarily true.

Jim

[jwoytek]

Originally Posted by Cruisingdad

There are two 120v inputs. One runs Air conditioners, one runs everything else. There is no power share inside the boat.

Is all of the physical wiring for those two circuits separate, though? If everything is 100% separate, then that makes things a little more strange, but you could still have current leakage somewhere that is overloading one circuit's neutral.

It really could be a combination of poor or degraded wiring in multiple places, dirty plugs or sockets that are raising resistance, and connectors that are not necessarily of the highest quality (though, for the record, I've probably seen just as many toasted Hubbel connectors as I have other not-so-great brands, but the Hubbels keep their act together a little longer ).

If you do end up with an electrician inspecting the power at dockside and on your boat, I'd be interested to hear what he or she had to say about the neutral overloading issue.

jonathan

[Cruisingdad]

Originally Posted by jwoytek

Is all of the physical wiring for those two circuits separate, though? If everything is 100% separate, then that makes things a little more strange, but you could still have current leakage somewhere that is overloading one circuit's neutral.

It really could be a combination of poor or degraded wiring in multiple places, dirty plugs or sockets that are raising resistance, and connectors that are not necessarily of the highest quality (though, for the record, I've probably seen just as many toasted Hubbel connectors as I have other not-so-great brands, but the Hubbels keep their act together a little longer ).

If you do end up with an electrician inspecting the power at dockside and on your boat, I'd be interested to hear what he or she had to say about the neutral overloading issue.

jonathan

It is all seperate. They do that becaues having two ac units along with the other loads would be more than a 30a could take.

The receptacles are hubbel, the cords are Marinco.

Both boats are fairly new and fresh water boats, so I do not feel corosion would be much of an issue.

- CD

[ebs001]

The problem only seems to be occurring on the neutral of the female end of the power cord. Given this, it illiminates a number of possible problems. 1. If it's strictly overcurrent you would see problems at the receptacle and it would occur on the line side as well. 2. I considered the possibility of harmonics but again you would see a problem at the receptacle as well. 3. Low voltage is a non issue as it's the flow through a resistance that causes heating. That only leaves a problem with how well the contact is made. the slot and the blade of the neutral are smaller so there is not as much surface contact and that leaves me to wonder if the female portion is smaller in the power cord cap than in a recepltacle. This could be resolved by manufacturers by ensuring there is larger contact with the male blade. I would be interested to know if anyone is seeing the same problem regularily occurring at the dock receptacle.

[SEMIJim]

Originally Posted by LarryandSusanMacDonald

What is code though is that the ground cannot be common with the neutral at the distribution (breaker) box if the box is located on the dock. The neutral and ground MUST run separately all the way to the shore. That is code.

By "distribution panel" I was referring to the panel immediately following the facility's service entrance. Again: Not a licensed electrician, but somehow I doubt anybody's taking L1, L2 and neutral directly from the power company and running it straight out to pedestals.

Originally Posted by LarryandSusanMacDonald

The "opposite phase" vs. "split phase" is just semantics. Technically, you are probably correct, however, in my meager mind it means the same thing.

Thus my noting I was picking nits . I just wanted to clarify that it isn't really two separate phases.

Jim