Faulty breaker or other cause?

[Suijin]

So the breaker for my autopilot will not stay on. It trips immediately like there is a short or overload. However, it also trips when I turn off the master DC breaker. Does this point to a faulty breaker or is there another potential cause? I can’t think of one.

Negative for the AP goes to the negative busbar. All the wiring is less that one year old and visual inspection it all looks good. Has functioned fine up until now. Breaker also less than a year old.

I was thinking the fault was in the computer as it was behaving strangely (missing menu options, then saying it needed commissioning after cycling the power) after a software update the day before this started but now I’m thinking that was coincidental.

[CharlieJ]

What is the rating of the breaker? What size breaker is recommended by the AP manufacture? If these two match, then a good clamp meter that has the capability of capturing in-rush current will tell you a lot. No clamp-meter?-disconnect the load conductor from the breaker and temporarily install a load that is close to the same as the APand see if the breaker holds when turned on.

[Suijin]

Thanks Charlie. The breaker is 40 amp, the AP has a 30 amp fuse in it, for the ram. The AP is disengaged (clutch not energized) so the ram is not drawing amps. The specification in the installation manual (installation was done by a certified B&G tech) was for the breaker to be larger than the fuse, that is all.

I don't have a clamp meter, and I can't think of anything that I could connect that is close to 40 amp.

I just took the positive off the breaker (dunno why I did not try this first off) and it is still tripping so it must be broken.

Question now, is there anything that could have fried the breaker...I never held it on, always let it flip back. Will replace and report back.

[CharlieJ]

OK Suijin; the Devil is always in the details. The 30A fuse downstream from the 40A breaker is the key since it did not open. Clearly a faulty circuit breaker. Why did it fail...probably a latent manufacturing defect unless there is apparent physical or heat damage present on the breaker.

[Cheechako]

Faulty Marine breakers are quite common. Replace it. I had two go out within a week of each other. not overloaded, or warm etc. just kept flipping off.
Interestingly, I helped build a group of small boats for the Marine Corps. Their spec didn't allow breakers, only fuses.

[Suijin]

It was the breaker. Whew. The alternative would have been going through B&G's warranty repair gauntlet, which is incredibly unsupportive.

Interestingly, most of my breakers are original to the boat, 32 years old. Never occurred to me that a 9 month old breaker could just up and fail like that. Yet another thing to make sure I have spares for. Who makes the best marine breakers? The one that failed (and what I replaced it with) is Blue Seas.

[Cheechako]

I'm not sure if any are better or not, or if they are all made by the same sub manufacturer. I know for years they looked the same , like the old Marinetics type. Do the Blue Seas look like that? Blue Seas should replace that for you.
It seems to me that most of these breakers are labeled to 250 volts 50/60hz ... which may indicate they are not "marine" designed at all. ?
What does your Blue Seas say on it?

[Suijin]

So the Blue Seas Systems breakers (the A series, with old school toggle switch) are made by Carling Technologies. General specs are "1-6 poles; ratings from 0.02 to 50 amps, up to 277VAC or 80VDC; UL Recognized, UL Listed, UL1500, UL1077, TUV, VDE & CSA".

The 40 amp A series breaker I'm using is indeed 250 volts 50/60hz.

On the Carling site for the A series it's pretty clear that they manufacture a variety of designs. Nothing about environmental protection other than "A sealed toggle actuator style is also available and ideal for harsh environment applications requiring additional sealing protection." That version is "Sealed metal toggle option tested to
MIL-PRF-55629C. Meets IP68 Requirements" but it appears the rest do not in any way.

[noelex 77]

Originally Posted by Cheechako

Faulty Marine breakers are quite common.

+1

Make sure your breakers can be easily replaced. Many modern boat switch panels use integrated proprietary breakers that are difficult, if not impossible to replace. This is a shortsighted design. The problems of this trend are further compounded because the number of circuit breakers seems to be diminishing, despite the increasing complexity of boat electrical systems. The reduced number of circuit breakers increases the consequence of any single failure.

Switching DC is hard. There is no collapse of the waveform, as occurs with AC. This means each switching operation produces a spark which erodes the contact surfaces. Switching even high voltage AC is much easier than low voltage DC. Replacing circuit breakers with fuses and a switch simply transfers the difficult current interruption to the switch. The combined failure rate, in a marine environment, of a fuse + switch + the required connections, is probably higher than a circuit breaker. Fuses have other problems.

Easily replaceable circuit breakers are the ideal answer in most circumstances.

[Lake-Effect]

Originally Posted by noelex 77

Switching DC is hard. There is no collapse of the waveform, as occurs with AC. This means each switching operation produces a spark which erodes the contact surfaces.

You can extend the life of circuit breakers by not using them as the only switch, whenever possible. By this I mean make sure that the loads are off by other means (eg their own switch, or by ensuring things like autopilots are disengaged or in standby) before turning the breaker off.


Ordinary switches are cheaper than breakers.

[Cheechako]

Originally Posted by noelex 77

+1

Make sure your breakers can be easily replaced. Many modern boat switch panels use integrated proprietary breakers that are difficult, if not impossible to replace. This is a shortsighted design. The problems of this trend are further compounded because the number of circuit breakers seems to be diminishing, despite the increasing complexity of boat electrical systems. The reduced number of circuit breakers increases the consequence of any single failure.

Switching DC is hard. There is no collapse of the waveform, as occurs with AC. This means each switching operation produces a spark which erodes the contact surfaces. Switching even high voltage AC is much easier than low voltage DC. Replacing circuit breakers with fuses and a switch simply transfers the difficult current interruption to the switch. The combined failure rate, in a marine environment, of a fuse + switch + the required connections, is probably higher than a circuit breaker. Fuses have other problems.

Easily replaceable circuit breakers are the ideal answer in most circumstances.

Yeah, they are placed under buss bars and everything else and you have to disassemble the whole thing to replace!

[noelex 77]

Originally Posted by Lake-Effect

You can extend the life of circuit breakers by not using them as the only switch, whenever possible. By this I mean make sure that the loads are off by other means (eg their own switch, or by ensuring things like autopilots are disengaged or in standby) before turning the breaker off.

Yes this is very good point.

The spark and degradation of the contact surfaces of the circuit breaker is diminished or even eliminated if all devices connected to the circuit breaker are switched off before the circuit breaker itself is turned off.

If you have hard to replace circuit breakers this is by far the best practice.

However, in many products the problem is somewhat transferred to switch within the device itself.

In simple terms if you switch devices off via the circuit breaker, the circuit breaker life will be less, but if you switch devices off via their internal switch then this internal switch, and therefore the device itself, is more likely to fail.

The above is a little simplistic as some devices use electronic rather than mechanical switching mechanism, at least in part.

For most marine circuits switching the device off first rather than the circuit breaker, if this is practical, is the best policy. The boats circuit breakers are very unlikely to last the life of the boat. In contrast most devices, even if they have a mechanical switch or relay will be obsolete by the time their internal switching mechanism fails.

[Boatyarddog]

Advice from and Automotive, Marine Technician, always diagnose the problem starting with the basics.
Then graduate to the complex, eliminating the known working parts of the system.
You'll save so much time this way.
It so easy to get buried in the details, that it compounds the simplest of problems.
Cheers,
SV Cloud Duster

[zeehag]

is there a possibilitiy of water running past or onto that breaker?? is what my issue was with breaker fail i replaced over 8 breakers in under 3 yrs due to water ingress and flow down mizzenmast, where the negative bus bars were installed and too close to the panel which had no room to breathe just forward of mizzen with only 2 inches between mast and panel.
yes i have a GOOOD mast boot, and yes i check frequently..my breakers cracked and then failed. heat plus water makes failure easy.

[Sailorbob8599]

Not being an 'expert' on marine electrical, I used all "Blue Seas" product when building my electrical panels, believing it to be the very best quality product available. I surely hope this is not an indication of an error in my choice of product???