Reverse Polarity

[rwidman]

Originally Posted by Miniyot

In the US, the wire from the polarized neutral WILL (might be) be attached to the metal frame and housing EXCEPT when the appliance is double insulated.....................

Once again, this is incorrect. The neutral wire is not attached to an appliance frame. The green ground wire is attached to the frame. This is the only wire that is attached to the frame.

[K_V_B]

Originally Posted by Miniyot

IF the European standard were to be so much better and safer there would not have been 2.5 million people who received an accidental shock (350,000 severely injured, 22 killed) (2010 data for Great Britain, not all of europe).

In Great Britain sockets are polarized. Electricity standards in the UK are not representative for continental Europe.


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[K_V_B]

Originally Posted by letsgetsailing3

Your assertion was "polarity doesn't matter". That was incorrect in general, and incorrect for the OP.

That was never my assertion. I said that it _should_ not matter. It's all down to proper wiring and practices.



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[rwidman]

"Proper wiring and practices" are not left up to the imagination, they are dictated by code and are very specific.

[letsgetsailing3]

Originally Posted by K_V_B

No it doesn't.

Not if the boat is properly wired.

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If a boat is wired to prevailing standards, it's properly wired.

Take up your issue with the standards committee. But don't go telling people that polarity doesn't matter. It might matter on their properly wired boat, and they should certainly pay attention to it.

[svlamorocha]

Originally Posted by Miniyot

In the US, the wire from the polarized neutral WILL (might be) be attached to the metal frame and housing (snip)

This is is not a rule, only an exception restricted to home wiring built to pre-1996 code that does not have a safety ground wire.

Unfortunately this "grandfathering" of old home installations made to a weaker safety standard ends up being turned into a reason not to embrace modern approaches to safety on boats (RCDs, etc).

IMHO part of the reason is the common use of codes (instead of first principles) as a learning tool. IMHO many educated Europeans take a different approach because they know that when you take your boat (or RVs) to another country you cannot rely on the code being the same (or code being complied with) and have to keep safe from both ends. That is why you find RCDs in both boats and marina pedestals!

If you buy a washer/dryer for a boat (say the Splendide WD2100XC found in the Antares boats ) you can just plug it into a normal 3-prong grounded 120V outlet on the boat and there will be a "best practice" safe installation without connection of frame to neutral.

[svlamorocha]

Originally Posted by Miniyot

Please quote the text of 1996 NEC 250.60 In The 2008 version that has to do with air terminals and the code hasn't changed THAT much!

Here is the wording from 2014 NEC. The numbering changed between 1996 and 2002. The wording has kept moving towards best engineering practice, which is to separate safety ground from neutral.

250.140 Frames of Ranges and Clothes Dryers. Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be connected to the equipment grounding conductor in the manner specified by 250.134 or 250.138.
Exception: For existing branch-circuit installations only where an equipment grounding conductor is not present in the outlet or junction box, the frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be permitted to be connected to the grounded circuit conductor if all the following conditions are met (snip).

Originally Posted by Miniyot

As for NEC 250.140? Read ALL of it AND you also need to understand that on a 3 wire 120/240 volt system, there is no neutral only a ground. (snip)
There are several exceptions listed for existing circuits. For example, if your home was wired before the adoption of the 4 wire system, and you get a new dryer, range, etc. then the "neutral" is bonded to the frame.

Understood and agreed, but this is not allowed for new installations (because it has been clear for a while that is not as safe)

Originally Posted by Miniyot

The ground was being used as a return path for any unbalanced current (120V timers).

IMHO That was another bad practice from an engineering standpoint (did not allow whole-house RCD) but with a bit of luck was been taken out by 2011 NEC 404.2. I think we both we all agree on the history of US code exceptions for old houses. Let´s just make sure we do not anyone to conclude to use those exceptions for old American houses as examples of good stuff to do today on a boat.

[DotDun]

Originally Posted by rwidman

"Proper wiring and practices" are not left up to the imagination, they are dictated by code and are very specific.

A code that has changed over time.....hence the bulk of the arguments on this thread.

[Miniyot]

Originally Posted by K_V_B

In Great Britain sockets are polarized. Electricity standards in the UK are not representative for continental Europe.


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GB is a part of the european standard....

So, now you are backpedaling?

[MarkSF]

Originally Posted by rwidman

OK, I get it, Europe is way better that the USA. Just remember though, you would all be speaking German today if it wasn't for the Good Ole' USA!

It would be remiss of me if I didn't point out that the principle language of Switzerland, spoken by 75% of its citizens, is..... German.

Anyway, here's a list of countries that contributed forces to the D-day invasion :

United Kingdom
United States
Canada
Australia
Belgium
Czechoslovakia
Denmark
Free France
Greece
Netherlands
New Zealand
Norway
Poland

My hat off to anyone, from any country, including the US, who made such an enormous sacrifice, to defeat evil. It's hard for me to believe how brave they must have been.

For the sake of historical accuracy, and without meaning to reduce anyone's contribution, the majority of the D-day invasion forces were British.

[K_V_B]

Originally Posted by letsgetsailing3

If a boat is wired to prevailing standards, it's properly wired.

Take up your issue with the standards committee. But don't go telling people that polarity doesn't matter. It might matter on their properly wired boat, and they should certainly pay attention to it.

I don't have an issue with the standards committee.

[K_V_B]

Originally Posted by MarkSF

It would be remiss of me if I didn't point out that the principle language of Switzerland, spoken by 75% of its citizens, is..... German.

German is official language in quite a few countries. It is in Belgium (where I grew up) and is indeed the common language where I now live.
I never had a problem with that. I speak four languages.

My hat off to anyone, from any country, including the US, who made such an enormous sacrifice, to defeat evil. It's hard for me to believe how brave they must have been.

The town where I grew up was liberated by Poles. I always found it tragic that after having liberated us they returned home only to find out their their towns had not been liberated. Only the occupying force had changed. For large parts of Europe WWII only really ended in the 89...

[K_V_B]

Originally Posted by Miniyot

GB is a part of the european standard....

So, now you are backpedaling?

No.. I'm not back pedalling. I never considered GB part of Continental Europe... Nor do the Brits for that matter.

[K_V_B]

Originally Posted by svlamorocha

Spot on!

Furthermore, IMHO it is silly to argue about reverse polarity without a clear understanding of the the earthing system being used. I believe that the Wikipedia article someone posted (Earthing system - Wikipedia, the free encyclopedia) can help a lot those who have electrical experience in only one of those settings.

There is no "best" solution; there are pros and cons to each. Let´s compare the US to a place where they use TT earthing such as Argentina, Malaysia or remote parts of some developed countries (or France, I am told).

The most common earthing system for residential buildings in those parts of Europe I have experience with is indeed TT. So you can add Belgium, The Netherlands and Switzerland to that list. And I assume Germany as well.
Often a copper loop would be buried under the foundations. The Utility would provide 3L+N. N is earthed at the substation.
To the best of my knowledge such a TT earthed system with a RCD is safe.

TT requires you to have a ground rod for the green at your end (ie in the marina), which is one more thing to worry about, but it does not become unsafe if a neutral breaks and it does not really care about polarity.

But isn't your boat earthed as well? Ie, you don't need to rely on a proper ground rod at the marina.
So if your boat is properly earthed, and has a whole boat RCD you should have all the possible danger scenarios covered.

The way I see it, it can become a problem if the boat is on land (as another poster experienced) and no longer properly earthed but that can be solved as well, by earthing the boat...

[svlamorocha]

Originally Posted by K_V_B

The most common earthing system for residential buildings in those parts of Europe I have experience with is indeed TT. So you can add Belgium, The Netherlands and Switzerland to that list. And I assume Germany as well.
Often a copper loop would be buried under the foundations. The Utility would provide 3L+N. N is earthed at the substation.

Thanks for the info.

Originally Posted by K_V_B

To the best of my knowledge such a TT earthed system with a RCD is safe.

I agree. Of course you are referring to a nice Euro-style 30mA RCDs whole-boat/house RCDs that will only trip if there is something wrong.

[Start rant] If you believe the US story that you need a 5mA because 30mA will kill you then you end up with a bunch of cheap outlet-mounted RCDs that will trip for no reason or don´t trip when they need to. I know of many people that got saved by a 30mA RCD (including me) so I will not believe the US wisdom on RCDs, which is founded on some mysterious studies that go against what people see in Europe and South America every day. [End rant]

Originally Posted by K_V_B

But isn't your boat earthed as well? Ie, you don't need to rely on a proper ground rod at the marina.

Yeap, you could use a ground plate for AC safety ground to protect those inside the boat (as when toaster frame gets hot) and disconnect ourselves from the shore green.

Only drawback could be that a swimmer might get zapped if you have a leak that is under 30mA. That said, I have taken 30mA many times and did not do me any harm, and the swimmer will only get a fraction of the leak. So I am with you on this.

Originally Posted by K_V_B

So if your boat is properly earthed, and has a whole boat RCD you should have all the possible danger scenarios covered.

Agree!

Originally Posted by K_V_B

But isn't your boat earthed as well? Ie, you don't need to rely on a proper ground rod at the marina.
So if your boat is properly earthed, and has a whole boat RCD you should have all the possible danger scenarios covered.

The way I see it, it can become a problem if the boat is on land (as another poster experienced) and no longer properly earthed but that can be solved as well, by earthing the boat...

Agree again. If btrayfors had sunk a rod next to the boat and tied his green to it he would not have been zapped by the green that was in fact tied to a broken neutral upstream.

The only problem of all this is that it requires people to understand how things work, as opposed to blindly extrapolating rules based on the time when it was deemed good to save one wire to have more copper to fight the War, or relying an a magic "reverse polarity light" or "oulet tester" that does not really test that the green wire is close to real ground that you stand in or water that you swim in.