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Old 12-07-2013, 01:42   #1
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Can't find cause of Reverse Polarity.

I just pulled into a marina in the Philippines and tried hooking up to their electrical system. They run on 220 so I pulled out my trusty step down transformer and plugged it into the system. Hers is how it it laid out--Marinco style plug into the outlet on the dock. that wire then comes on board where the stepdown transformer. I then plug my Marinco cord into it and that goes into my boat. Simple set up. The Reverse Polarity light on my circuit panel lit up like a Christmas tree. I'd talked to the yard manager and he advised me that they used the Marinco style plugs and to make sure I put the grounding wire to the prong of the plug that has a hook on it. Add on the positive and the negative and all should be fine. I checked my plug and that was exactly how it was wired. OK, I'll reverse the positive and the negative wire and see if that makes any difference--Nope. Still Reverse Polarity. I tried and different plug and got the same.
The marina hired an electrician that looked at the wires and the box they came from and said the system that they used doesn't really need the ground wire and we should disconnect our plug from it. The tech took his multi meter and stuck the wires into my outlet and still got a reading even though there was no wires attached to the plug I was using at the junction box. I took off the ground wire at the plug and that stopped it. But still, I had Reverse Polarity.
Now I know it's not the wiring inside the boat as I run a small Yamaha generator on my stern and use some of the same wires and everything works just fine. No Reverse Polarity.
The electrician is baffled and has no clue as to what the problem is and neither do I.
Any one have any suggestions as to what I can try next to fix the problem? Hate using my generator when I don't have to.
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Old 12-07-2013, 04:05   #2
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Re: Can't find cause of Reverse Polarity.

This is 220 volts AC?

Some time ago member Gord May wrote this:-
Reverse Polarity (AC)
Reverse Polarity

This common problem is one that should be thoroughly understood by all boaters. Reversed polarity can exist on the dock or within your own boat, which should be equipped with a Reverse Polarity Indicator (RPI) on your main AC electric panel. Regardless of whether the reversing point is on the dock or in you own boat, this is going to energize the neutral ground and create an electrical shock hazard. It should not find its way into your bonding system because these circuits should never be joined.

Keeping track of which wire is the Neutral (white) is necessary in order to prevent potentially dangerous voltage differences from existing between one boat and another, connected to the same or separated shore-power systems. In a properly wired AC system, there should be no significant voltage difference between the white Neutral wire and the green safety Ground wire. Therefore, an incorrect connection may be detected by sensing a current flow between the neutral wire from the shore power system and the electrical system's safety ground wire.

Upon detection of a reverse-polarity indication on any boat the shore power should be immediately disconnected and the shore-power system wiring on the dock inspected. It may be that the polarity of the shore power is reversed from the normal or the neutral is "floating" and not properly referenced to ground. It is also possible that the shore power safety ground wire (the green wire) may not be connected to proper earth ground. Connecting to an improperly wired shore-power system can create potentially harmful conditions for personnel as well as damaging galvanic currents.

Perhaps the easiest way to visualize the working of a Reverse Polarity Indicator (RPI) is to first visualize the relationship of the Safety Ground and Neutral wires. In a normal marine installation, when connected to shore power, these two wires are are not connected on the boat, but are connected together on shore at the system grounding point.

The job of the RPI is to determine if there is voltage potential between Safety Ground and Neutral. The Safety Ground and Neutral are effectively two ends of the same wire and therefore should have the same voltage potential and not be capable of lighting the RPI.

One further ABYC requirement for RPI's is that they contain a minimum 25,000 Ohm Resistor. A full treatment of the reason for this is beyond the scope of this article. It is sufficient, however, to say that because the Safety Green wire is connected to devices aboard the boat that may contain stray currents, the link created by an RPI could provide a path for stray currents via the grounded Neutral wire. (See also Note 3)

It is possible for such a circuit to faintly illuminate the Reverse Polarity light even though the circuit is properly wired. It is useful for boaters to understand how this can occur.

Because voltage is always consumed pushing amperage through a resistance (wire), the voltage is different at points A and B on the Neutral wire when there is current flowing through it. This is called “voltage drop”. When high amperage loads are operated in the circuit, enough voltage drop in the length of the Neutral wire can be created to overcome the resistance in the 25K resistor required by ABYC that sufficient current is driven through the LED to cause faint illumination. This situation is not inherently dangerous, however, it can indicate undersized wiring in the dock, shorepower cord or ship’s wiring portion of the AC circuit.


From ABYC E-8.10 SHORE POWER POLARITY DEVICES

E-8.10.1 Reverse polarity indicating devices providing a continuous visible or audible signal shall be installed in 120 V AC shore power systems and must respond to the reversal of the ungrounded (black) and the grounded (white) conductors (See E-8.23.1, Diagram 3,)
if
E-8.10.1.1 the polarity of the system must be maintained for the proper operation of the electrical devices in the system,
or
E-8.10.1.2 a branch circuit is provided with overcurrent protection in only the ungrounded current-carrying conductors per ABYC E-8.11.6.1

E-8.10.2 Reverse polarity indicating devices are not required in systems employing polarization or isolation transformers that establish the polarity on the boat.

E-8.10.3 The total impedance of polarity indicating and protection devices connected between normal current carrying conductors (grounded [white] conductor and ungrounded [black] conductor) and the grounding conductor shall not be less than 25,000 ohms at 120 volts, 60 hertz at all times.

NOTES:
1. Reverse polarity indicating devices respond to the reversal of an ungrounded conductor and the grounded (white) conductor only when there is continuity of the grounding (green) conductor to shore.

2. Reverse polarity indicating devices might not respond to reversals of an ungrounded conductor and the grounding (green) conductor, the grounded (white) conductor and the grounding (green) conductor, or three phase conductors.

3. Another strategy (NOT recognized by the ABYC) is to install a Momentary “Push to Test” Pushbutton in series with the RPI. The has the effect of entirely disconnecting the RPI from the circuit, until you test for polarity (by pushing button when you first connect to shore power).

4. I highly recommend the use of an AC Receptacle Tester* (circuit analizer), which will also indicate reversed Neutral & Ground, and open grounds etc. Test the Marina’s Shore Power System prior to (immediately upon) connecting your shore power cable.

A few examples:

*GB Electrical GFI-501A (And GB #GRT-800) Ground Fault Receptacle Tester & Circuit Analyzer - Tests for seven conditions: GFI interruption, open ground, open neutral, open hot, hot/ground reverse, hot/neutral reverse, and correct wiring.

*Ideal Model 61-035 tests for open ground, reverse polarity, open hot, open neutral, hot and ground reversed, hot on neutral, and hot open.
Ideal Model 61-051 also checks GFI-protected outlets against trip at minimal leakage current of 2mA, and tests their mechanical operation (with the push of a button) by intentionally overloading the GFI breaker with a 6.8mA current through the ground blade.

Regards,
Gord
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Old 12-07-2013, 09:40   #3
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Re: Can't find cause of Reverse Polarity.

There is no positive or negative in the Alternating Current.
I suspect something with your transformer. Have you checked the polarity there?
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Old 12-07-2013, 09:45   #4
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Re: Can't find cause of Reverse Polarity.

I believe he knows that, what he has is a problem with is A 220 Volt system, as Gord pointed out a few years back- In a properly wired AC system, there should be no significant voltage difference between the white Neutral wire and the green safety Ground wire and i think that's the issue?
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Old 12-07-2013, 10:32   #5
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Re: Can't find cause of Reverse Polarity.

Reverse polarity in an AC system only applies when one leg is "hot" and the other is grounded ("neutral"). In this case the neutral leg should have no voltage as compared to earth ground, and the hot leg should have the system voltage when compared to earth ground.

In the US a neutral would generally be white or gray in color and most systems are 120V. In the EU most system are 220V and neutral is blue in color under harmonized color schemes, however older systems may not use harmonized color schemes.

Not all systems, and in particular not all 220V systems use a neutral. In the US a standard 220/240 system uses two hot wires. No neutral need be present. In the EU the harmonized standard is to use one hot and one earthed (neutral), however this is not universal, particularly in older Eastern European systems. In other parts of the world it is even more sporadic. Some systems may use an earthed (neutral) conductor while others may not.

The reverse polarity detector is looking for a voltage difference between what it considers the neutral and earth ground. If the "neutral" is in fact not so the RP detector will light up.

With a multimeter check the voltage from all legs to earth ground. If there is any voltage on the "neutral" then it is likely not neutral. It may just be poorly earthed at some location in the marina system, or it may not be intended to be earthed at all. Need to determine if the system even has a real neutral before you can proceed further.
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Old 12-07-2013, 13:48   #6
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Re: Can't find cause of Reverse Polarity.

Often built-in polarity detectors LEDs will glow dimly which suggests there is a problem with old or faulty pontoon wiring. The Neutral and Earth wire are joined at the main transformer supply so should be at the same potential. Under a heavy load there’s a voltage drop along the neutral wire, but because no current is flowing in the earth wire there is no voltage drop along the wire, so there is now a voltage difference between the neutral and the earth which is enough to dimly light the polarity detector; this should never be more than 5 volts. Above this earth leakage breakers or RCDs may keep tripping. In winter months the problem is much worse because the more power that is taken by other boats then the higher the earth/neutral voltage difference will be.
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Old 14-07-2013, 14:58   #7
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Re: Can't find cause of Reverse Polarity.

A quick look at the Global Electrical Directory Electricity Around the World
shows that the power provided is 220VAC @ 60Hz. Note that this is single phase; that is there is 220VAC between hot (L) and neutral (N). The RPI is wired between N and G thru a 25kohm resistor as noted above.

NOTE: I am unsure as to whether there is a G>N bond at the transformer. Some countries do not make this bond.

Here are the trouble shooting steps I would perform to isolate the problem:
SHORE SIDE
- Unplug the boat from shore power.
- At the shore power pedestal, measure the voltage from L>N (should be 220VAC); L>G (should be 220VAC if they bond N>G at the transformer) and N>G (should be close to zero volts again, if they bond N>G, but there may be 5 to 10VAC present if there is a long wiring run from the transformer to the dock pedestal.

BOAT SIDE
If the boat is wired as 220VAC single phase (not USA split phase) than, with the shore power unplugged go to a convenience outlet and check for continuity between L>N (open); L>G (open); G>N (open).

Hope this helps.
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Old 14-07-2013, 15:17   #8
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Re: Can't find cause of Reverse Polarity.

In parts of the Philippines, it is possible the pedestal has no neutral to ground. Both sides being hot to ground.
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Old 14-07-2013, 15:36   #9
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Re: Can't find cause of Reverse Polarity.

I ran into this problem in Italy. Over there, house current is 220vac & 110 vac does not exist anywhere in the country. They don't use a neutral wire on anything. Because of this, Italians have no idea what a neutral connection is or how it needs to be hooked up.

If your polarity indicator is telling you that there is a polarity problem on the AC system, then it is most likely a grounding problem, unless you are trying to feed AC into your boat from more than 1 source at the same time.

If it is the grounding problem, then you do not have the correct leg of the 110vac grounded or you have ground going to one of the power legs. This condition leaves you at risk of electrical shock.

If you are trying to feed AC from more than one source at the same time (like from shore power & also from an inverter that is powered by your batteries) then you need to shut off the extra source or else run it through a special device called a synchronizer that you probably don't have. You can't just put two AC feeds in parallel like you can with DC.

If you have an incorrect polarity indicator on your DC system, then that is a different story.
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Old 14-07-2013, 15:48   #10
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Originally Posted by pbiJim View Post
I ran into this problem in Italy. Over there, house current is 220vac & 110 vac does not exist anywhere in the country. They don't use a neutral wire on anything. Because of this, Italians have no idea what a neutral connection is or how it needs to be hooked up.

If your polarity indicator is telling you that there is a polarity problem on the AC system, then it is most likely a grounding problem, unless you are trying to feed AC into your boat from more than 1 source at the same time.

If it is the grounding problem, then you do not have the correct leg of the 110vac grounded or you have ground going to one of the power legs. This condition leaves you at risk of electrical shock.

If you are trying to feed AC from more than one source at the same time (like from shore power & also from an inverter that is powered by your batteries) then you need to shut off the extra source or else run it through a special device called a synchronizer that you probably don't have. You can't just put two AC feeds in parallel like you can with DC.

If you have an incorrect polarity indicator on your DC system, then that is a different story.
This post is quite frankly rubbish , Italians use single phase 230vac , there is a live , neutral and protective earth wire . The ops config is simple its a 220 to 110 stepdown ,

Dave
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Old 14-07-2013, 16:02   #11
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OP what's is the configuration of the boats AC earth wire ( ground wire ) it quite possible that the N and E connections ant the isolating traffo output are not connected. This would float the boats neutral in respect of the boats earth wire ,RPI neons require so little current to fire that it could be misleading you

Note that because your using a step down isolating transformer, the reverse polarity isn't dangerous ( and may not actually exist)

Dave
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Old 14-07-2013, 16:21   #12
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Re: Can't find cause of Reverse Polarity.

The difference in the Philippines is it is 220 v 60 hz, but it is just ground on one conductor and 220v on the other conductor.

Difference is the US is 220v 60 hz one ground with two hot (120v and the other 120v) with potential between the two hot being 220v (or if you like 240v).

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Old 14-07-2013, 18:37   #13
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Re: Can't find cause of Reverse Polarity.

Quote:
Originally Posted by goboatingnow View Post
This post is quite frankly rubbish , Italians use single phase 230vac , there is a live , neutral and protective earth wire . The ops config is simple its a 220 to 110 stepdown ,

Dave
What part are you claiming to be rubbish? Italy has 2 types of voltage, 220vac single phase & 380vac 3 phase, all of it 50hz. They have ground (earth) connections along with that, but no neutral. Neutral is a US thing where one side of the power is tied to ground ( the neutral wire, white) & the other side is called hot (usually red or black). In the US, red to black is 220vac & either red or black to white is 110vac. In Italy, the ground floats & the voltage from ground to either of the power wires is random.

The step down transformer may or may not have one leg of either winding (primary or secondary) tied to neutral. Depending on how his sensing equipment is wired, a polarity fault may be indicated. No? Also, you assume that he is using an isolation transformer. He may be using a less expensive buck/boost transformer. No?

If I am missing something, please explain it to me.

Thanks,
Jim
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Old 14-07-2013, 19:14   #14
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Originally Posted by pbiJim View Post

What part are you claiming to be rubbish? Italy has 2 types of voltage, 220vac single phase & 380vac 3 phase, all of it 50hz. They have ground (earth) connections along with that, but no neutral. Neutral is a US thing where one side of the power is tied to ground ( the neutral wire, white) & the other side is called hot (usually red or black). In the US, red to black is 220vac & either red or black to white is 110vac. In Italy, the ground floats & the voltage from ground to either of the power wires is random.

The step down transformer may or may not have one leg of either winding (primary or secondary) tied to neutral. Depending on how his sensing equipment is wired, a polarity fault may be indicated. no?

If I am missing something, please explain it to me.

Thanks,
Jim
I think this maybe your confusions with definition , live and neutral are the terms used in Europe , ( brown and green wire in domestic leads ) neutral may or may not be ground referenced by establishing a local ground. Its still called a " neutral"


Italy has a standard European single phase setup . ( let's leave 3phase out of this)

Italy has a live ( designated L ) a neutral ( designated N) and in some cases , and all new installations , an Earth ( ground wire) .

Neutral/prptective esrth can be established in several different ways as can the ground connection , as per IEC 64-8 in Italy this is done by connecting the protective earth to neutral at the meter, rather then establishing an earth ground via a rod ( as is common in France )

Traditional Italian sockets are three pin un- polarised, with the centre pin ground. Hence reverse polarity is not a priority. Marina installations will use the IEC blue polarised socket. ( but polarity maintenance is not always maintained in my experience )

Ground wire is really an incorrect term , because neutral may or may not be at ground potential , the key thing is that continuity exits between neutral and protective earth wire , otherwise the fault protection doesn't exist.

Isolating step down transformers , typically have the input earth wire tied to the case of the transformer and optionally the electrostatic shield of the windings.

The output is therefor a floating supply that is not earth referenced , to establish the functionally of the protective " earth" wire circuit on the boat , the earth wire and the neutral ( ie an arbitrarily side of the transformer so designated) are connected at the transformer output. This ensures existing breakers and fuses will trip in an earth fault. Note that with the transformer there is actually no " earth" fault per say

If the boats earth wire isn't connected at the transformer output , then the RPI actually hasn't a circuit at all or may strike because there is minute leakage paths

Dave
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Old 14-07-2013, 20:25   #15
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Re: Can't find cause of Reverse Polarity.

Dave,
Thank you for the in-depth description.

Apparently, the few times that I have been to the UK have not been enough to bring me up to speed on all the common electrical terminology that is used there.

Apparently, you & I had made some different assumptions. It appears to me that you may have assumed that an isolation transformer was used, probably of the type that I saw used in England when 110v electric drills were used in industrial sites. Not knowing where the OP's boat had been wired or where the transformer had been purchased, I left open the possibility that perhaps another type of step down transformer (such as a buck/boost) may have been used.

Cheers,
Jim
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