It's what you learn after you know it all that matters.

[M. R. Bober]

The light on the panel that indicates AC power would not light until the main breaker was energized.

Assuming the boat is wired as shown in the manual, the only way I can think of that would cause this is an open neutral. The power pilot light is connected to the line side of the main breaker. It should light when plugged in with the breaker off. If it doesn't, but does light when the the breaker is turned on it appears that the light is now getting it's "neutral" via the ground (green) wire rather than the real (white) neutral.

The wiring is as specified.

Mitchell Bober
Sunny Lancaster, (ibid) VA

[swhfire21]

Alex for double jeopardy, "What would the effect of internal corrosion and a short in a breaker be?"

[M. R. Bober]

Alex for double jeopardy, "What would the effect of internal corrosion and a short in a breaker be?"

That's hard to know, but those conditions were not present.

Mitchell Bober
Sunny Lancaster, (ibid) VA

[bottomscraper]

Might there be more than one problem?

I'm having a hard time understanding how the AC pilot light only working with the main breaker on could be anything other than an open neutral someplace before the main breaker. That still doesn't explain the 30 amp breaker tripping when the other breakers are turned on.

Is you VOM digital or analog and what actual measurements did you make?

[M. R. Bober]

Might there be more than one problem?

I'm having a hard time understanding how the AC pilot light only working with the main breaker on could be anything other than an open neutral someplace before the main breaker. That still doesn't explain the 30 amp breaker tripping when the other breakers are turned on.

Is you VOM digital or analog and what actual measurements did you make?

Digital. Checked continuity and voltage. You are on the right track.

Mitchell Bober
Sunny Lancaster, (ibid) VA

[Oswego John]

Hi Mitchell,

Hmmm. I think maybe I'll get my feet wet and look into this poser. I have to ask a few questions first.

#1 Is the main breaker popping when hooked up to the GFCI shore power or to the non GFCI shore receptacle?

#2 Is the battery charger hard wired or plugged into a ship's receptacle?

#3 What size AWG conductors are feeding the charger and the ship's receptacles?

#4 What size amp breakers are being use for the branch circuit(s)?

I'm concentrating on why a 30 Amp main will pop when a charger or receptacle circuit is activated. I'll probably ask more questions about the ground and neutral supply. I'm also interested in the adapter used between the shore power and the ship's main breaker.

And then again, maybe all of my questions are moot???

O J

[M. R. Bober]

Hi Mitchell,

Hmmm. I think maybe I'll get my feet wet and look into this poser. I have to ask a few questions first.

#1 Is the main breaker popping when hooked up to the GFCI shore power or to the non GFCI shore receptacle?

#2 Is the battery charger hard wired or plugged into a ship's receptacle?

#3 What size AWG conductors are feeding the charger and the ship's receptacles?

#4 What size amp breakers are being use for the branch circuit(s)?

I'm concentrating on why a 30 Amp main will pop when a charger or receptacle circuit is activated. I'll probably ask more questions about the ground and neutral supply. I'm also interested in the adapter used between the shore power and the ship's main breaker.

And then again, maybe all of my questions are moot???

O J

#1 Originally the breaker tripped on the GFCI breaker, but did not on the non-GFCI breaker. Later it tripped on the non-GFCI.
#2 Hard wired
#3 10 gauge for the charger and CD original for the outlets (12 gauge I think)
#4 15A

The adapter is a MARINCO twist lock 30A with a male common plug on one end http://www.wholesalemarine.com/marinco- ... Al3S8P8HAQ

The Board has had the question for about as long as I did. Of course you did have to climb down & up a ladders.

Mitchell Bober
Sunny Lancaster, (ibid) VA

[bottomscraper]

I assume if you had an inverter you would have told us about it already and that you charger is only a charger not an combination inverter/charger.

So using a digital VOM for measuring voltage won't tell you anything much about a high resistance connection. Even measuring resistance won't tell you much about behavior under load. (Memories of problems with one of those cheapo "Seadog Line" starter buttons....)

Why would't the 15 amp breakers trip first? The only thing I can think of is there is already some significant load on the 30 amp breaker even without any individual breakers turned on. I would try an measuring amperage on the black hot wire coming into the main breaker with other breakers turned off just to be sure.

Might it be something really weird like +12 shorted (with about 1/3 ohm resistance) to AC neutral along with a bad neutral connection before the main breaker? Grasping at straws........

[M. R. Bober]

I assume if you had an inverter you would have told us about it already and that you charger is only a charger not an combination inverter/charger.

So using a digital VOM for measuring voltage won't tell you anything much about a high resistance connection. Even measuring resistance won't tell you much about behavior under load. (Memories of problems with one of those cheapo "Seadog Line" starter buttons....)

Why would't the 15 amp breakers trip first? The only thing I can think of is there is already some significant load on the 30 amp breaker even without any individual breakers turned on. I would try an measuring amperage on the black hot wire coming into the main breaker with other breakers turned off just to be sure.

Might it be something really weird like +12 shorted (with about 1/3 ohm resistance) to AC neutral along with a bad neutral connection before the main breaker? Grasping at straws........

No inverter. I like your reasoning.
If no one solves it by the time there have been 400 reads, I'll tip my hand.

Mitchell Bober
Sunny Lancaster, (ibid) VA

[M. R. Bober]

We all seemed to follow the same diagnostic paths. So we are equally good (or bad) at troubleshooting.

My route:
When the shore power breaker (GFCI) tripped and I moved to a non-GCFI and had initial success, I thought my heavy duty extension cord had a damaged conductor. So I changed to another power cord (12 gauge), but that did not resolve the problem.

Next I moved my power cord to a different receptacle on the power pole. That provided some (a few hours) of service before the ship's main breaker tripped. This was the third receptacle that I used.

At this point, I opened the ship's electrical panel. Typical CD rat's nest to be sure. With power off I found continuity to be excellent where it should be and opened where it shouldn't be. This is when I found the brown crud around the ring connectors. I cleaned the contacts, but this didn't resolve the problem.

OBTW: I must have gone up & down the ladder 25 times resolving the problem.

I'd like to talk about Ohms' Law for a moment. While there are differences between AC and DC (impedance vs resistance and phase cycle), at root there is great similarity amperage is a function of voltage and resistance (load). I had measured voltages many times during the trouble shooting.

After cleaning the contacts, the AC indicator lamp stopped lighting until the main 30A breaker was energized. Clearly this indicated an open somewhere (hot or neutral). While checking voltage (again) I found 32VAC (hot to neutral & hot to ground) instead of the expected 120VAC. Going back to Ohms' Law, I believe the voltage drop drove the amperage above the 30A that the main breaker was designed to handle. It was also at this time that I discovered a floating neutral and ground at the shore power.

The power pole at the yard had 4 quad 120 20A receptacles. I used 3 of the 4 on a single quad. The yard's power to that quad seemed to come and go as other loads were applied. Once I moved to a different quad, all of the problems were resolved.

Morals of the story: 1) Sometimes the trouble isn't on the boat, 2) Intermittent problems are a beast, 3) Repeated measurement are essential, and 4) It's always the last thing that you check.

I'm sorry there were no winners, but I think that had you been at the yard, you would have found the problem quickly.

Mitchell Bober
Sunny Lancaster (All power to the people!) VA