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Old 13-02-2015, 00:47   #61
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Re: Reverse Polarity

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Originally Posted by rwidman View Post
This is an example of where a little knowledge can be worse than none at all as explained in post #46.

Most electrical appliances will work just fine with the polarity reversed. The problem is, they can be dangerous with the polarity reversed.

This is why we have polarized receptacles and reverse polarity indicators.

A device that becomes unsafe when polarity is reversed cannot be sold in Europe. It's that simple. Now since I see both UL and CE marks on everything with a plug nowadays I assume that appliances sold in the US will not care about polarization either.

In a way a boat is an appliance as well. A big one, but still one you plug in. The shore power for our family boat comes through an extension cord plugged in a power socket in the garage of my parents weekend home. I'm sure that N and L are reversed half of the time. It is not an issue.

It is possible to wire a boat in a way that reverse polarity does not lead to danger. The examples that have been posted here to prove the contrary all have in common that the problem really is with the boat. Like binding neutral and earth together when on shore power. Something you shouldn't do even when you can rely on N not being live...

Relying on shore power being wired correctly for your boats safety is like relying on the weather being good when setting out to sea...





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Old 13-02-2015, 02:05   #62
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Re: Reverse Polarity

You are a very foolish...man/woman!

Not because of what you preach....

But, because you don't understand, what you preach????

But, you are right in your own mind, because someone else, confirmed that to you.

But, were they right?

Yes, it must be true, because that is what I believe!!!

the poet


Quote:
Originally Posted by K_V_B View Post
A device that becomes unsafe when polarity is reversed cannot be sold in Europe. It's that simple. Now since I see both UL and CE marks on everything with a plug nowadays I assume that appliances sold in the US will not care about polarization either.

In a way a boat is an appliance as well. A big one, but still one you plug in. The shore power for our family boat comes through an extension cord plugged in a power socket in the garage of my parents weekend home. I'm sure that N and L are reversed half of the time. It is not an issue.

It is possible to wire a boat in a way that reverse polarity does not lead to danger. The examples that have been posted here to prove the contrary all have in common that the problem really is with the boat. Like binding neutral and earth together when on shore power. Something you shouldn't do even when you can rely on N not being live...

Relying on shore power being wired correctly for your boats safety is like relying on the weather being good when setting out to sea...





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Old 13-02-2015, 07:28   #63
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Re: Reverse Polarity

Quote:
Originally Posted by K_V_B View Post
A device that becomes unsafe when polarity is reversed cannot be sold in Europe. It's that simple. Now since I see both UL and CE marks on everything with a plug nowadays I assume that appliances sold in the US will not care about polarization either.

In a way a boat is an appliance as well. A big one, but still one you plug in. The shore power for our family boat comes through an extension cord plugged in a power socket in the garage of my parents weekend home. I'm sure that N and L are reversed half of the time. It is not an issue.

It is possible to wire a boat in a way that reverse polarity does not lead to danger. The examples that have been posted here to prove the contrary all have in common that the problem really is with the boat. Like binding neutral and earth together when on shore power. Something you shouldn't do even when you can rely on N not being live...

Relying on shore power being wired correctly for your boats safety is like relying on the weather being good when setting out to sea...





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I wish you would get off the "Europe is better" track that you seem to be so stuck on. It's completely irrelevant to those in the USA and the electrical system there is not better, just different. I also suspect you don't know as much about electricity as you are trying to claim.

A boat (with a shorepower system) does not compare to an "appliance", it compares to an electrical sub panel like one might have in a barn or outbuilding. It has a master breaker and individual protected branch circuits. Appliances may be connected to or plugged into these branch circuits.

The reason we have reverse polarity warning lights is, we move this "sub panel" from place to place with no guarantee that the place we move it to is wired correctly.

None of this helps the OP who apparently either took the advice to move to another marina or is running his genset for power.
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Old 13-02-2015, 09:48   #64
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Re: Reverse Polarity

Quote:
Originally Posted by rwidman View Post
I wish you would get off the "Europe is better" track that you seem to be so stuck on. It's completely irrelevant to those in the USA and the electrical system there is not better, just different. I also suspect you don't know as much about electricity as you are trying to claim.
I'm not saying "Europe is better". That is what you are making of it. I am only illustrating that some of the assertions made here are false. Like the assertion that appliances become unsafe or even get damaged when live and neutral get reversed.
This has nothing to do with EU versus USA. It has to do with fact versus fiction. I know electricity, I'm an engineer by training. But I don't need my electricity knowledge to detect a logical fallacy.

Quote:

A boat (with a shorepower system) does not compare to an "appliance", it compares to an electrical sub panel like one might have in a barn or outbuilding. It has a master breaker and individual protected branch circuits. Appliances may be connected to or plugged into these branch circuits.

The reason we have reverse polarity warning lights is, we move this "sub panel" from place to place with no guarantee that the place we move it to is wired correctly.
Which is why it is a good idea to wire this "sub panel" in a way that reverse polarity is never an issue. Something the AYBC seems to believe as well, as they only make a reverse polarity indicator mandatory if you don't have a RCD.
And since you should have an RCD...

Quote:
None of this helps the OP who apparently either took the advice to move to another marina or is running his genset for power.

The OP probably did not suffer from a reverse polarity situation, as his measurements showed. Having to move marinas because of a false positive is a pity.


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Old 13-02-2015, 09:55   #65
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Re: Reverse Polarity

Quote:
Originally Posted by FlyingCloud1937 View Post
You are a very foolish...man/woman!

Not because of what you preach....

But, because you don't understand, what you preach????

But, you are right in your own mind, because someone else, confirmed that to you.

But, were they right?

Yes, it must be true, because that is what I believe!!!

the poet

Who is the fool here.

The person that keeps saying: "you need to put your socks on in the right order, or you drop dead"

Or the person that says: "I see lots of people everywhere that don't care about which order they put their socks on, and they're doing just fine"


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Old 13-02-2015, 11:24   #66
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Re: Reverse Polarity

Quote:
Originally Posted by K_V_B View Post
Which is why it is a good idea to wire this "sub panel" in a way that reverse polarity is never an issue. Something the AYBC seems to believe as well, as they only make a reverse polarity indicator mandatory if you don't have a RCD.
And since you should have an RCD...
By the way, given US practice of having continuous green across the iso transformer, if the marina gives you a hot in the green wire (as must have been the described by Bill) then an RCD in the boat will not save you from electrocution if you touch any bonded metal while standing on earth painting your boat or get close to it when swimming. A shore RCD would be required but Americans for some reason do not like whole-circuit RCDs.


A reverse polarity light will detect the hot green only if neutral is correct. If green is actually hot and hot/neutral are swapped then the reverse polarity light will not turn on.

The case described by Bill is not is not about hot/neutral reversal (ie reverse polarity, which may cause a hot green only if the ground rod is missing; otherwise it will trip a breaker upstream) . It is about green that is actually hot (regardless of what the white and black wires do).

I guess the learning for me is: Make sure shore green is actually "close" to real earth that you can touch. Otherwise make sure you have an iso transformer, break the green connection across it, and connect boatīs green to white downstream of the transformer.
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Old 13-02-2015, 11:27   #67
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Re: Reverse Polarity

Not trying to insult any of the fine engineers out there (I really mean that), but whenever one of my customers was an engineer and they made a big deal about it, I would try to find ways to get off his/her boat because I knew my life would be a nightmare. By and large, they were the ones who insisted on looking over my shoulder every second while I corrected the wiring on their boat and argued with everything I did.

It's a standing joke in the boatyard industry. I also had some absolutely great customers who were engineers. They either just didn't want to do work they could do themselves (time, energy, whatever), or, they knew that they might not understand all the nuances of boat wiring even when they knew they could figure it out if they put the time into it. But hey, I started out as an engineering major until I decided that engineering was too much detail for me. I like to keep the big picture and ignore the small stuff LOL. But if someone tells me they are a nuclear scientist or electrical engineer as I get on their boat just to impress on me how much they understand wiring, I get very nervous.

They wouldn't have me on the boat until something went wrong, or just didn't follow their prediction of what they should see. I just deleted a big story about how I got on a boat with an engineer who had a reverse polarity on just one outlet and found he had wired this custom boat using white for hot and black for neutral. He lectured me on how I was wrong in the color standard, and in any case, it didn't matter. Until I found he had hooked white to white and black to black going in to his inverter/charger. Not a good thing. I also found that he was not consistent and would other places swap the colors so hot was black. I did not like working on his boat. Standards do matter sometimes and they are helpful at all times.
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Old 13-02-2015, 12:54   #68
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Re: Reverse Polarity

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Originally Posted by exMaggieDrum View Post
I just deleted a big story about how I got on a boat with an engineer who had a reverse polarity on just one outlet and found he had wired this custom boat using white for hot and black for neutral.[...]. Standards do matter sometimes and they are helpful at all times.
You keep deleting good stuff

Now, as standards (codes) go, colour choice differs in Europe. Here we have:

PE - green/yellow
N - blue
L1 - brown
L2 - black
L3 - white (or light grey)

Just for information to US cruisers visiting Europe, as neither white, nor black will be neutral which might be a shocking surprise (pun intended). Voltage and frequency will differ too..

As a side note, most appliances here are indeed double-isolated, come with two-pronged symmetrical plugs which can be plugged either way and are designed without assumption to which wire is live and which is neutral.

Some appliances, those with metal cases (mostly ovens, refrigerators and similar) or user accessible metal parts, come with plugs with a third connector for PE. They are also designed without assumption of which wire is L and which is N. Case is _only_ bonded to PE.

Finally, most bulb sockets are plastic ;-) and those with outside metal shell are built so, that the shell is not connected to any of supply wires (but may be bonded to PE, if available).

P.S.:
Quote:
Originally Posted by FlyingCloud1937
In the US we have determined that it only takes 15 millivolts across the hear to put you into defib. That's why all US GFCI's are rated at the same.

I agree with the use of 30 millivolt RCCB/ELCB's as now promulgated by the ABYC for shore power entrance circuits. As I also agree with the GFCI additional requirements in wet areas.
In other areas of the world it would be 15/30 milliAmperes [mA]. Is US really that different?
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Old 13-02-2015, 13:13   #69
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Re: Reverse Polarity

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Originally Posted by mrm View Post
Finally, most bulb sockets are plastic
Where in the Land of Lost Toys?

This thread is awesome:
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Old 13-02-2015, 13:31   #70
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Re: Reverse Polarity

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Originally Posted by thomm225 View Post
Where in the Land of Lost Toys?
In Europe. I was under the impression, that Cruising, by definition, may involve visiting places far away from home, where standards may differ. Therefore it is good to know and understand some details which may influence one's life..

Typical examples:
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Old 13-02-2015, 14:14   #71
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Re: Reverse Polarity

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Originally Posted by mrm View Post
You keep deleting good stuff

In other areas of the world it would be 15/30 milliAmperes [mA]. Is US really that different?
Yep, of course i meant mA, as we all know 15 mV could not carry enough ampers to kill you.

In the US Class A GFCI's have a 5mA nominal rating, for residential wet areas,
1.no trip below 4mA (no load)
2.must trip at 6mA (no load)
3.no trip below 4mA (with load) at rated voltage
4.must trip at 6mA (with load) at rated voltage
5.must trip with 2 ohm grounded neutral
6.must trip within 25 ms with a 500 ohm fault
7.must trip with test button at +10/-15% rated voltage
8.must not trip with noise test of GFCI Standard
9.calibration test at +10/-15% rated voltage
lloyd
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Old 13-02-2015, 15:47   #72
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Re: Reverse Polarity

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Originally Posted by mrm View Post
In Europe. I was under the impression, that Cruising, by definition, may involve visiting places far away from home, where standards may differ. Therefore it is good to know and understand some details which may influence one's life..

Typical examples:
Not all of us are Cruisers...............some of us just like sailing, boats, and being around the water.

You are slanting this of course. You found a few plastic sockets online to display. You said most are plastic, but that isn't the case.

I have enough engineer in me to argue pointless small details for fun also.

I see it every day with my workforce.

Metal sockets:

https://www.google.com/search?q=meta...33%3B425%3B271
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Old 14-02-2015, 02:42   #73
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Re: Reverse Polarity

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Originally Posted by thomm225 View Post
You are slanting this of course. You found a few plastic sockets online to display. You said most are plastic, but that isn't the case.
No, I am not slanting anything. I simply present, for enlightenment (p.i.) of readers, how it looks in Europe. I admit I used images found in catalogues of local online distributors, but I can take similar pics myself if you like. It won't change the message though.

Quote:
I have enough engineer in me to argue pointless small details for fun also.
For an engineer, you, Sir, are quite rude. Next time, before you accuse me publicly of slanting facts, please do your own research.

As a general remark, this thread drifted a lot from the OP question, but, at least for me, was very informative and, at times, eye opening. For example I would never have thought, that bulb sockets with metal shell being part of the circuit could ever be allowed on consumer market in devices operating on live AC. In my area, such designs are restricted to low voltage devices.
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Old 14-02-2015, 03:43   #74
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Re: Reverse Polarity

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Originally Posted by rwidman View Post
This thread is not about whether the European standard for electrical wiring is better than the USA standard, it's about a guy whose boat is showing "reverse polarity" when it shouldn't. The reverse polarity light is a warning of an unsafe condition and that is what I believe he is asking for help with.



As for the isolation transformer meaning the problem is not with the shore power wiring, his boat seems fine everywhere else except at this marina. We don't have a diagram of how the boat, transformer and shore power are wired so we can only guess. As I posted above, my experience is that wires don't detach themselves from connections and reattach themselves to different connections by themselves so moving wires as the OP did is not the solution.



We don't know if the isolation transformer is permanently installed on the boat or if he plugs it into the dock pedestal and plugs the boat into it. Perhaps the problem is with his shorepower cable but one would think he would have tried another before posting here.



Perhaps his problem is that the ground is not being carried through from his boat to the power pedestal.



If you can provide a workable solution to the OP's problem, I'm sure he would be grateful. Rewiring his boat is probably not the solution he is looking for.


I answered this. The fact is simply having an illuminated polarity light in itself should not be and is generally not " unsafe "
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Old 14-02-2015, 03:57   #75
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Re: Reverse Polarity

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Originally Posted by btrayfors View Post
Here in the U.S., reverse polarity is dangerous and potentially lethal. Period.

Some examples have been given above. Here's another from personal experience.

A few years ago I hauled my boat for a bottom job. I plugged one of my 30A shore cords into the pedestal in the work area of the boat yard.

When I walked by my propeller and shaft, I happened to touch it and received a 120-volt shock! If the ground had been wet or I'd been barefoot or...any number of other scenarios....I"d likely have been ELECTROCUTED. KILLED. DEAD.

The boatyard's shorepower pedestal was wrongly wired....black hot and white neutral were reversed. This put 120VAC on my boats GROUND system (AC ground and DC ground on the boat were connected to a single-point .... the engine.... in one of the common and "approved" marine wiring practices).

It's pointless to argue whether the European system is better than the American system. The point is, we in North America have several HUNDRED MILLION people using the 120-volt system and it works pretty well for us. The best statistics available show about 50-60 accidental electric shock deaths annually in the U.S......not too bad with over 200,000,000 users!

I'd bet the rate of accidental deaths in 240-volt system countries is much higher, partly because of the increased lethality of 240VAC vs. 120VAC.

No matter. Our system is what it is. And the other systems are what they are.

Bill

If you own a boat with AC neutral and DC ground connected I recommend you get that fixed fast.

ABYC requires protective earth and DC neutral connected.

I trad these posts by predominantly US posters arguing things they simply don't understand. Or simply arguing the " code " is right.

Reverse polarity because of deficiencies in US electrical codes has some issues.

Bit No boat should become " unsafe " merely because the live and neutral ate swopped.

Furthermore mention by posters of reversing investors or chargers and causing damage is pure fiction

I'm familiar with NEC and ABYC.

THE. FACT is that if you leave the confines of your beloved US electrical code YOU WILL come across situations where neutral is either floating symmetrically or at elevated potential. You should therefore make sure your onboard systems do not become unsafe , if they are therefore not unsafe , reverse polarity if of little consequence

Dave

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