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Old 20-05-2012, 21:21   #1
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marinetics polarity test

Just recently my polarity test light (on/ok) does not illuminate when the polarity test button is pressed. I am in Australia where the shore power is 240/250v. My battery charger is a Mastervolt which accepts any power input. My guess is that the indicator light was designed for 120v and it may have burned out. Does anyone have any info regarding this and a technical explanation of how the polarity test works would be appreciated. Thank you.
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Old 20-05-2012, 21:59   #2
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Re: marinetics polarity test

To simplify the explanation, I will assume a 30A/120VAC shore power system. Normally, there is 120VAC between line (hot) and neutral and between line and safety ground. Under ideal circumstances, there will be 0VAC potential between neutral (N) and safety ground (G). Under real world conditions, a reading of 1 or 2 VAC is not uncommon between N > G.

A reversed polarity indicator is wired between the neutral of the shore power service and safety ground through a minimum of a 25,000 ohm resistor. The resistor ensures that N and G are isolated on board. The function of the reverse polarity indicator is to test if line and neutral have been mis-wired (reversed) on the shore side. If they have, then the N onboard will be hot in relation to the safety ground and the reverse polarity indicator will illuminate.

If your boat was originally wired for 30A/120VAC service, then it is quite possible that the indicator bulb has been destroyed by over-voltage.

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Old 21-05-2012, 02:28   #3
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Re: marinetics polarity test

Quote:
Originally Posted by flyer24 View Post
Just recently my polarity test light (on/ok) does not illuminate when the polarity test button is pressed. I am in Australia where the shore power is 240/250v. My battery charger is a Mastervolt which accepts any power input. My guess is that the indicator light was designed for 120v and it may have burned out. Does anyone have any info regarding this and a technical explanation of how the polarity test works would be appreciated. Thank you.
Assuming your polarity test light is PART of the Mastervolt battery charger which is designed to accept any power input, then I would expect the polarity test light section would also be designed to handle any input voltage. By any input voltage, I assume you mean somewhere between 100 VAC and 250 VAC, 50 or 60 Hz.

Is this polarity test function for the AC input or the DC output?


If it isn't part of the Mastervolt BC, then what is it part of?

BTW, welcome aboard F24.
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Old 21-05-2012, 04:57   #4
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Re: marinetics polarity test

Greetings and welcome aboard the CF, flyer24.
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Old 21-05-2012, 05:18   #5
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Re: marinetics polarity test

Thank you for the quick reply. The "polarity test light" only illuminates if the button is depressed. It is labeled "on/ok". I assume that if the shore side polarity was reversed the light would not illuminate when tested. I think you are correct about the overvoltage. Thanks again.
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Old 21-05-2012, 05:33   #6
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Re: marinetics polarity test

I apologize for not being more clear. The polarity test is part of the Marinetics AC panel. I think the company is out of business. The reason I mentioned the Mastervolt charger is because it will accept 120-240v input. 240v is what I am using in Australia. I'm quite sure that the indicator light was designed for a stateside 120v shore power system.
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Old 21-05-2012, 05:52   #7
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Re: marinetics polarity test

The “Push to Test” Button is wired in series between the White Neutral and the Indicating Test Light.
See ➥ http://cdn.cruisersforum.com/attachm...larity-med.jpg
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Old 21-05-2012, 06:09   #8
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Re: marinetics polarity test

Quote:
Originally Posted by flyer24 View Post
Thank you for the quick reply. The "polarity test light" only illuminates if the button is depressed. It is labeled "on/ok". I assume that if the shore side polarity was reversed the light would not illuminate when tested. I think you are correct about the overvoltage. Thanks again.
Quote:
Originally Posted by GordMay View Post
The “Push to Test” Button is wired in series between the White Neutral and the Indicating Test Light.
See ➥ http://cdn.cruisersforum.com/attachm...larity-med.jpg
Hmm... this doesn't make sense. According to the OP, the light should be on when system is OK but the circuit Gord posted works the other way - unless I have lost it .
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Old 21-05-2012, 07:06   #9
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Re: marinetics polarity test

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Hmm... this doesn't make sense. According to the OP, the light should be on when system is OK but the circuit Gord posted works the other way - unless I have lost it .
Nope - you're right, and you haven't lost it, yet.
As it turns out, I'm not certain how the Marinetics system is wired/works (er, his doesn't work).
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Old 21-05-2012, 12:33   #10
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Re: marinetics polarity test

Quote:
Just recently my polarity test light (on/ok) does not illuminate when the polarity test button is pressed. I am in Australia where the shore power is 240/250v. My battery charger is a Mastervolt which accepts any power input. My guess is that the indicator light was designed for 120v and it may have burned out. Does anyone have any info regarding this and a technical explanation of how the polarity test works would be appreciated. Thank you.
Are you sure this is what supposed to happen, normally the polarity light is not permanently wired in ( though it was on my boat) , but is wired through a pushbutton, this is to prevent the small leakage current being continually induced into the earth lead through the Neon. Ive seen many panels where you pressed the button and if the light didn't come on , all was well, you sure thats not how yours works
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