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Old 17-02-2012, 23:47   #1
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Reverse Polarity Light

I have a Blue Sea 120 volt AC Souce Selector breaker that has a green LED, which lights up for the source power (of which I have only shore power at this time), and a red LED light, which is to light up for a reverse polarity situation. My green LED stays on when plugged in, but the red LED is also on though very dim; it grows brighter when I increase the AC demands/amp draw. The green light remains bright green. What the hell? Ideas? Thank you in advance.
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Old 18-02-2012, 00:38   #2
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Re: Reverse Polarity Light

How old is it?

The increasing red could indicate a leaky diode somewhere in the system. Or you have current in the common leg from a short.
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Old 18-02-2012, 04:43   #3
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Re: Reverse Polarity Light

Greetings and welcome aboard the CF, gscriba.

See the Blue Sea Systems Technical Brief ➥ AC Reverse Polarity False Indicators
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Old 18-02-2012, 05:24   #4
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Re: Reverse Polarity Light

The red light will come on when there is a voltage differential between the neutral and ground wires The neutral and ground are tied together somewhere back on shore. Because of voltage drop in the cabling between your panel and that point, a small voltage differential will occur, causing the red lamp to glow dimly. This is normal.
It will glow brightly if the neutral and live are reversed, which is what it is intended to detect.

Marner
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Old 18-02-2012, 06:10   #5
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Re: Reverse Polarity Light

Gord's reference to the Blue Sea white paper is an excellent start to understanding the problem.

Some questions:
  1. Is this a new condition?
  2. Have you changed slips?
  3. Do your neighbors have the same condition?
  4. Do you have, and know how to use a DMM?
A simple circuit tester such as the common three light outlet tester (Receptacle tester - Wikipedia, the free encyclopedia) will help find a gross problem onboard, but this test is performed with no load on the circuit so it can provide satisfactory results for an unsatisfactory condition. This tester is cheap and quick so I would recommend it as your first step.


From your description, it appears that there is either undersized wiring in the circuit, either shore side or on your vessel, or you have current leakage from neutral to ground. The easiest way to test the health of AC circuits is by using an IDEAL Sure Test Circuit Analyzer (61-154/61-155 or the newer 61-164/61-165). ( SureTest® Circuit Analyzer) If you can find a marine electrician with one of these pieces of test equipment, you can quickly locate your problem.


If you have no luck finding a marine electrician with the IDEAL Analyzer, than you will have to do some additional testing.

THE FOLLOWING TESTS REQUIRE TAKING MEASUREMENTS ON ENERGIZED ELECTRICAL CIRCUITS. DO NOT PERFORM THESE MEASUREMENTS UNLESS YOU ARE COMFORTABLE AND COMPETENT IN WORKING ON ENERGIZED ELECTRICAL CIRCUITS.

Assuming that the Blue Sea Panel is wired and functioning correctly, bring shore power aboard:
  1. Check the voltage at a distant outlet between neutral and ground. Voltage should be ≤ 2VAC.
  2. If possible, increase the load on that circuit one load at a time and note the voltage at the distant outlet between neutral and ground.
  3. Note the brightness of the reverse polarity LED with each new load.
  4. Repeat by monitoring the same outlet, but turning on all of the AC loads on board.
Come back to the Forum with your results.


Hope this helps.
Charlie
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Old 18-02-2012, 10:42   #6
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Re: Reverse Polarity Light

I agree with Marner. Don't worry about it. It's normal to see a faint glow when you put a heavy load on the AC system. Mine worked the same way, and checked out fine with a receptacle tester. Buy one for $3.95 if you want peace of mind.
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Old 18-02-2012, 10:53   #7
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Re: Reverse Polarity Light

Marner/Hud3: OP stated "...it grows brighter when I increase the AC demands/amp draw." which indicates a problem that should be investigated.

Charlie
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Old 18-02-2012, 11:24   #8
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Re: Reverse Polarity Light

Perhaps the attached diagram will help.

At the end of long runs, such as encountered in marinas or when using long power cords the wiring resistance can be considerable, the voltage between neutral and ground can also be affected by other users on the same circuit.

Marner
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Old 18-02-2012, 12:35   #9
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Re: Reverse Polarity Light

Thank you one and all. This is a new issue since moving into a new marina (very new and modern marina), so new slip to us. I have a 30 amp plug and cord, breaker close to the boat end receptacle (which incidentally has both a green and red LED light, neither of which are lit...this is also new though I cannot say when they stopped working; just noticed this a few days ago), 10 gauge 3 wire to my source selector, then to my Blue Sea 5 breaker distribution panel. We often pull 20 amps while heating the boat at the dock (we live aboard), charging the house bank, heating water or using the microwave; then the hot water heater kicks in, we bump up to a full 30 amps. No red LED at all without draw. If I remember correctly (and I can easily check, no time right now) I have 12 gauge 3 wire port and starboard lines on separate breakers, 12 gauge 3 wire to my built-in wall heater, and 12 gauge 3 wire to both the battery charger and hot water heater (on separate breakers). I am certain that the problem is voltage differential as suggested, but I will be sure to confirm. There are no live aboards adjacent to us, but I will ask others further down the finger re: their experience. Thank you!

Any thoughts as to why my LED's on the very first Blue Sea breaker are not functioning? Also, there is one green LED on the distribution panel (the one indicating when the battery charger breaker is on) that is not functioning; I have purchased a replacement from Blue Sea, but not replaced it yet. The panels and breakers are all approx. 8 years old. Can I chalk this up to age? Voltage irregularities in the marina? Thanks.
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Old 19-02-2012, 06:24   #10
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Re: Reverse Polarity Light

Quote:
Can I chalk this up to age? Voltage irregularities in the marina?
If the LED's are still properly wired across the load side of their respective circuit breakers and neutral, then yes they have probably failed because of age or abuse by an out of spec condition.

Charlie
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Old 19-02-2012, 08:52   #11
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Re: Reverse Polarity Light

Thanks Charle.
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