A/C Breaker Panel

I almost had a disaster this evening.
While dozing off I smelled electrical insulation burning.
The TV was on and I had turned the heater on 10 minutes earlier. I thought possibly the return on the heat exchange might have been plugged and the motor was cooking so I started to pull the cover off of that but before I got it open I heard the TV sputter off and I had already turned off the heater.
I turned off all the ac and dc breakers (should have done that first)and started searching for the source of the burn. I opened the panel that my breakers panels are mounted on and the top double throw breaker for the rest of AC panel had one lead completely burned through, wire and all.
It wasn’t overloaded in anyway so I’m not sure where to start. I don’t know why the breaker didn’t trip.
I checked continuity on both sets of contacts on the breaker and the switch worked just fine.
Heater?
Bad connection
Very old breakers and panel.
Anyway I’m going to sleep with the power unplugged at the dock. Fortunately only going down to 40 degrees tonight.
Any thoughts?

It may have been a loose or dirty connection. What wire was burned off? The supply or the wire going to the individual circuit? I would see which wire it was. If it was the supply from the inlet on the side of the boat, I would start there and check for burned or melted plastic on the inlet. Then follow the wires into the boat and check for loose or dirty connections. Maybe a photo would help narrow it down.

Post some pictures. It's easier to make suggestions with a clear understanding of what was damaged.

Ted

Frequently its the terminal ends that get corroded inside and get hot.

Decades ago it was common to use auto crimp ends and an auto crimping tool..

If this is the case perhaps a real crimping tool and marine terminal ends will let you sleep better?

FF said:

Frequently its the terminal ends that get corroded inside and get hot.

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This. Breakers protect against over current. Increased resistance in wires due to bad connections/corrosion generates heat.

Best recommendation: Get a marine electrician out to your boat to trouble shoot and correct the problem.

I'd be replacing all of the breakers and cutting and re-doing all of the connections in the panel. They're all (or at least MOST) were all installed at roughly the same time, using the same manufacturer and model parts, installed by the same person, the same way.

In my mind the entire panel is now suspect. The cost of the job is more time/labor than actual expense.

Shrew said:

They're all (or at least MOST) were all installed at roughly the same time, using the same manufacturer and model parts, installed by the same person, the same way.

In my mind the entire panel is now suspect.

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And, oh ya.......unless the panel was done once already, then everything in that panel is 43 years old.

A loose connection causes arcing. Often not visible, as it gets hotter it gets worse. Think arc welding.

If the connection was on the input to the breaker, then the breaker would not trip, it is downstream.

If on the load side, then it should have tripped eventually, if all working as intended.

You can not test a breaker except for continuity, does it open and close.

I would reterminate the wire, and then gradually increase the load, with the heater being last.

Watch the panel and feel for hot wires and burning plastic.

If the breaker is the same size as your shore power breaker, it should have tripped also.

I’m guessing it is on the incoming side. Ten gauge wire which is coming from the 10/2 position on the Ship/Off/Shore switch. It is only about a 5 inch wire coming from the switch to the breaker. You can see where it burned away from the breaker and the end of the wire sticking up in the first picture.
The burnt wire terminated on the switch and wire location is the big yellow lug on lower left of the switch picture 2
There is also a heavy gauge white wire coming off the bottom opposite side of the same switch which shows heat distress the first inch, 3rd picture.
I haven’t looked to see where it goes yet.
Yes, pretty old stuff! Airpax breakers

I'm not a licensed boat electrician, nor have I played one on TV, but IMO, you were very lucky. That whole system needs some serious attention.

Ted

Thanks

I agree

The verdigris is the smoking gun.... (pun intended). You need to remove stuff until you get to fresh shiny copper, and replace with fresh shiny tinned of the appropriate gauge. You may be replacing a lot.

And since you are going to spend a lot of quality time messing with this you may consider re-doing it all with 21st century stuff. It'll feel good when you're done. Except in your wallet, but hey.... it's a boat.

Have you checked your inlet for any signs of heating? Both the outside where the shore power cord plugs in and also the back of the inlet. I would carefully inspect the inlet and maybe replace it just in case. Then I would replace all the inlet feed wire from the inlet to the switch inside and then from the switch to the main breaker on the panel. Also look at replacing the main breaker in the panel and the shore power switch. Then you will have entirely new wire and connectors from the shore power inlet to the panel. While you are at it start looking at all the wire connections in the panel and the individual circuit breakers. If you are not certain you can do this work properly then get a certified marine electrician to help.

Unfortunately, moisture eventually wicks through the wire causing corrosion, often measured in tens of feet from the termination. I’d strongly suggest replacing the entire wire run, not just cutting back. Triage the highest current circuits and do them first. For hard to get to wire runs, do them as a group. Good quality wire with high quality insulation, tinned copper and heat shrink sealed terminals all cost quite a bit more, but in my opinion, completely worth it. Do it once or do it again. I get at least a decade, if not three, out of well constructed circuits, so after learning the hard way many years ago, I never use cheap stuff anymore for anything.

But good news, nothing complicated here, just a bit of work.

OldDan1943 said:

Best recommendation: Get a marine electrician out to your boat to trouble shoot and correct the problem.

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O C Diver said:

I'm not a licensed boat electrician, nor have I played one on TV, but IMO, you were very lucky. That whole system needs some serious attention.

Ted

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I agree with the above unless you are a marine electrician. Based on my experience, this is going to be an expensive repair and only should be done by a marine sparky.....

Alaskan Sea-Duction said:

I agree with the above unless you are a marine electrician. Based on my experience, this is going to be an expensive repair and only should be done by a marine sparky.....

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I respectfully disagree. I am not a "Professional Marine Electrician" but I know enough to do it properly, and have done so for years. Surveyors like my work. It is not rocket surgery. Now, if you're not confident, then by all means hire a pro.

oscar said:

I respectfully disagree. I am not a "Professional Marine Electrician" but I know enough to do it properly, and have done so for years. Surveyors like my work. It is not rocket surgery. Now, if you're not confident, then by all means hire a pro.

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Good deal. Keep us updated on your work with pic of course [emoji6]

Alaskan Sea-Duction said:

Good deal. Keep us updated on your work with pic of course [emoji6]

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It ain't his boat!

And the take away is - breakers will not protect you from over heating corroded high resistance connections. In older boats - an IR scan of wiring from time to time is not a bad idea. A very good Fluke or FLIR IR scanner can be rented by the day and could save your bacon. Was more than likely the cause of the Scottsboro Marina fire.




https://jmtest.com/c/rental/rent-electrical-test-equipment/thermal-imaging-camera-rental/

All good info and thanks.
I did look at my power cord and didn’t see any signs of arching but I could smell it.
The “Guy” will be here Saturday. I will keep you posted.

menzies said:

It ain't his boat!

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Nope, but there are updates in the future for my Hatt, including updating the dual 240/50A feed, main breakers, inverter etc. etc. And yes, I will be reporting here.

oscar said:

Nope, but there are updates in the future for my Hatt, including updating the dual 240/50A feed, main breakers, inverter etc. etc. And yes, I will be reporting here.

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Somewhere around 70% of the issues I find surveying are electrical in nature whether straight from the factory (more than you would believe) or from the various unqualified and multiple hands that have played with the systems over the years.

email me at boatpoker@gmail.com and I''l send you a copy of the ABYC electrical standards.

I believe that lots of boats come new with electrical issues. My boat has 2 30 amp inlets and it only had 1 main 30 amp breaker in the panel. The other inlet was tied into the main bus bar without any over current protection. And that is how it was built because I examined another one like mine and it was wired the same way. The surveyor missed it. And other previous surveyors must have missed it too. New panel with 2 30 amp mains fixed the problem.

Comodave said:

I believe that lots of boats come new with electrical issues. My boat has 2 30 amp inlets and it only had 1 main 30 amp breaker in the panel. The other inlet was tied into the main bus bar without any over current protection. And that is how it was built because I examined another one like mine and it was wired the same way. The surveyor missed it. And other previous surveyors must have missed it too. New panel with 2 30 amp mains fixed the problem.

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simple neutral/neutral bond test would have found it. I've only known 4-5 surveyors who even carry a multi-meter

This is a good example of why marine construction standards call for use of tinned wire.

boatpoker said:

I've only known 4-5 surveyors who even carry a multi-meter

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email me at boatpoker@gmail.com and I''l send you a copy of the ABYC electrical standards

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Have them.

I have a multi meter next to every measuring tape, utility knife and 10mm socket.... somewhere....

But seriously... having a good multi meter and knowing how to use it is indeed the first step in electrical troubleshooting/systems evaluation.

So, the electrician came today.
I showed him what had happened and told him the circumstances. Turns out no one device had issue. Looks like just a bad connection that got worse with load. It’s a 30 amp service and the main double gang 30 amp breaker doesn’t trip with more than 30 + amps. Also doesn’t trip the dockside 30 amp breaker. The heater is hooked up directly to the main breaker so does not have its own breaker.
I will be replacing the 40 + year old panel with new and and adding an extra breaker or two. I will have to watch my usage.
Did you ever watch Green Acres where all the electrical had numbers and a complicated system that had to be followed so not to burn up the farm generator?

Lived to tell about it so that is a good thing.

BonesD said:

Did you ever watch Green Acres where all the electrical had numbers and a complicated system that had to be followed so not to burn up the farm generator?

Lived to tell about it so that is a good thing.

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My AT34 has 2X30amp services. I have a second amp meter in the galley so I can regulate the load as I am cooking on the electric stove and oven.
First load to shed is the electric hot water heater. That usually solves the problem.

30 amp supply, tv, lights and then a heater? What else was on?