AC power tripping

ShawneH

ShawneH

.
Oct 29, 2013
44
Beneteu 373 Canoe Cove
I just purchased a B-373. I have been staying on it for the last couple of weeks.

Something I have noticed is occasionally the AC power just shuts off.

It doesn’t trip the breaker on the AC panel. So I usually switch off the breaker and wait a while and it starts working again.

I don’t know what causes this. Sometimes there is very little in the way of devices being plugged in or power being consumed over the very standard stuff like battery charger, and a few other odds and ends.

The boat has a smart plug, but that seems to also still be powered as indicated by the light on the power cord itself even when the boat loses AC power.

I am not sure if there are other breakers or something else I should be looking at to find out where this seems to be getting ‘tripped’ up.

Thanks!
 
D

dlochner

.
Jan 11, 2014
13,152
Sabre 362 113 Fair Haven, NY
Sounds like a loose connection. Check all the connections between the Smart Plug inlet and the breaker. Make sure they are well connected and corrosion free.

The other possibility is the Smart Plug, I believe it has a thermal breaker in it. If the boat side plug gets too hot it will trip and shut off power. This can happen because the load is too high and or it is baking in the sun with a moderate load.

Finally, breakers do wear out, especially ones also used as a switch. It may be the breaker is just worn and will trip easily and randomly.
 
B

BrianQ

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Jan 10, 2024
30
Hunter Legend 37.5 Havelock
Smart Plugs don't have a thermal breaker inside them so you can rule that out.

If resetting the AC breaker restores power the problem is most likely a faulty circuit breaker. It is not uncommon for lever type circuit breakers to exhibit a "silent failure". The breaker disconnects power, but the lever barely moves or does not move at all. This is mostly caused by worn parts in the breaker itself.
 
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jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,546
CAL 35 Cruiser #21 moored EVERETT WA
There can be only two sources causing the issue. It will be either External or Internal.

You state the power cord light is on after the brown-out or shutdown. This suggests the issue is internal, not external.

Great. Now, all you need to do is begin with the Power cord receptacle and follow the wires to the AC panel, looking for wires or connections that show wear or burn/smoke marks. If they are clean, you know the next potential issue is the AC Panel. The process of elimination is a powerful tool for isolating electrical problems. It is much better than asking if anyone else has had this problem. It saves you from saying, "Damn, I guess that didn't work. Now what?"

Good luck.
 
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BigEasy

BigEasy

.
Jun 21, 2004
2,975
Beneteau 343 Slidell, LA
jssailem said:
There can be only two sources causing the issue. It will be either External or Internal.. Now, all you need to do is begin with the Power cord receptacle and follow the wires to the AC panel, looking for wires or connections that show wear or burn/smoke marks. If they are clean, you know the next potential issue is the AC Panel.
Click to expand
Don’t overlook the double pole service breaker located just to the inside aspect of the power cord inlet. Should have a clear waterproof housing located inside the lazarette. Probably not the problem; however, it needs to be checked.
 
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D

dlochner

.
Jan 11, 2014
13,152
Sabre 362 113 Fair Haven, NY
BrianQ said:
Smart Plugs don't have a thermal breaker inside them so you can rule that out.
Click to expand
Early versions of Smart Plugs had thermal breakers in the inlet. At some point the breaker may have been discontinued.

From MarineHowTo.com:

Another Safety Feature
When Ken, the owner of SmartPlug, set out to design this product he wanted to incorporate a thermal-breaker into the inlet body to prevent melt downs, boat and marina fires due to high resistance. It was not good enough to just design a better plug & inlet, he wanted to design a truly safe product. Should be simple right?
Click to expand
 
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ShawneH

ShawneH

.
Oct 29, 2013
44
Beneteu 373 Canoe Cove
BigEasy said:
Don’t overlook the double pole service breaker located just to the inside aspect of the power cord inlet. Should have a clear waterproof housing located inside the lazarette. Probably not the problem; however, it needs to be checked.
Click to expand
This is definitely what I will check first. It hasn't happened again yet. I expect it's just a matter of time, but I will start here.

Thanks!
 
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ShawneH

ShawneH

.
Oct 29, 2013
44
Beneteu 373 Canoe Cove
When it rains it pours!

So today the power has gone off at least 4-5 times. I have my laptop plugged in and the water heater is on. That’s it.

Toral draw can’t be that much on a 30A connection. So it seems to be getting worse.

I assume if it’s a breaker somewhere, that breaker is getting weak. I checked the one in the lazerette directly opposite the smart plug and it is not tripped. The cord still has power coming from the pedestal. I might have to pull everything out of the lazerette and start tracking where all the power goes.
 
Tally Ho

Tally Ho

.
Jan 7, 2011
5,770
Oday 322 East Chicago, IN
So, the power cuts out…and without any intervention (you resetting a breaker) it comes back on?

Certainly sounds like some sort of thermal disconnect…not a typical breaker that needs to be reset.

No idea what it is.

Greg
 
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ShawneH

ShawneH

.
Oct 29, 2013
44
Beneteu 373 Canoe Cove
Tally Ho said:
So, the power cuts out…and without any intervention (you resetting a breaker) it comes back on?

Certainly sounds like some sort of thermal disconnect…not a typical breaker that needs to be reset.

No idea what it is.

Greg
Click to expand
Yup, that’s exactly what is happening. Only now it can’t handle 5-10amp without tripping so presumably this thermal breaker is faulty. That said, I did check it this morning and it wasn’t tripped. So maybe a sensor or something?

I might have to get a marine electrician to come look at it. I am not comfortable with AC loads in general let alone when it comes to a boat.
 
BigEasy

BigEasy

.
Jun 21, 2004
2,975
Beneteau 343 Slidell, LA
Turn off water heater to determine if problem persists. Could be an issue with the water heater circuit.
 
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ShawneH

ShawneH

.
Oct 29, 2013
44
Beneteu 373 Canoe Cove
BigEasy said:
Turn off water heater to determine if problem persists. Could be an issue with the water heater circuit.
Click to expand
I have turned everything off except outlets. No water heater, no battery charger. I don’t have any other random things plugged in anywhere.

In the outlets I have starlink and my laptop.

So power draw is minimal. Maybe 3-4 amps.
 
DaveJ

DaveJ

.
Apr 2, 2013
504
Catalina 310 Niagara-on-the-Lake
If it’s a thermal disconnect, a bad connection that heats up then cools down, you can sometimes smell it. Follow your nose, it may lead you to the issue. Electrical faults have a particular odour.
Good luck.
 
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jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,546
CAL 35 Cruiser #21 moored EVERETT WA
Thermal breaks indicate resistance in the line. The age of a breaker and bad or corrosion on the connector are usual suspects.

You have identified the dock circuit and the smart plug as good. Continue moving onward to the panel and breakers. Look for smoke or blackened wires. It is a process of elimination.
 
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Caboteur

Caboteur

.
Feb 21, 2010
351
Beneteau 31 016 St-Lawrence river
Would you have an automatic resetting GFCI? Once tripped the circuit remains open until you shut off power and turn it back on.
 
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