Reply
 
Thread Tools Search this Thread Display Modes
 
Old 01-16-2019, 08:05 AM   #1
Senior Member
 
BrianSmith's Avatar
 
City: Wherever Smartini is
Country: USA
Vessel Name: Smartini
Vessel Model: 2002 Kristen 52' Flybridge Trawler
Join Date: Mar 2014
Posts: 315
Totally fried wire into circuit breaker

Click image for larger version

Name:	Fried wire.jpg
Views:	152
Size:	57.3 KB
ID:	84309

Been in the same marina for 2 months, connected to the same shore power pedestal. During most days, we turn it off on our main circuit breaker panel and let the solar panels do the best they can, and in the evening, if it's not above 85% or so, we flip on the "Shore power" switch and leave it on overnight.

Last evening, I flipped on the "Shore power" switch and very quickly smelled blue smoke. Traced it to the attached picture. The wire going into the circuit breaker that provides AC power to our Magnum Inverter / Charger was totally fried, and the connection on the CB itself was destroyed (see picture). The breaker itself never flipped off.

Questions:
1. Why would the breaker not flip off? Other than "it's defective", which it very well may be, is there any other reason I'd see enough energy to fry that cable that would NOT flip the breaker? (By the way, in the past, when we've tried to run too many things through the AC side of the systemm, this breaker has flipped off, which says, I think, that it's at least in the ballpark of being the correct size - 30A.)

2. What could make this much amperage go through this wire? As noted above, the wire provides AC power to the Magnum Inverter Charger. In its current state (fried wire), the Magnum is still inverting just fine, but it won't go into "Charge" mode. The non-inverted AC items on the boat (such as the water heater and washer/dryer) are working fine. It's only the Magnum's charger function (used to charge the house bank only) that's out of commission because of the fried wire. And as noted above, the house bank was at 82%, so it didn't need some crazy unusual amount of amperage to charge it.
__________________
Advertisement

BrianSmith is offline   Reply With Quote
Old 01-16-2019, 08:22 AM   #2
Guru
 
angus99's Avatar
 
City: Signal Mtn., TN
Country: US
Vessel Name: Stella Maris
Vessel Model: Defever 44
Join Date: Feb 2012
Posts: 1,978
Don’t know if this is the cause, but it looks like you have two different sized wires connected to the same breaker lug—with the larger one on the outside. I was told that the larger loads/current-carrying conductors should always be the first to be connected to any post. Otherwise current that is too high may be drawn through the smaller wire/lug and something melts.
__________________

angus99 is offline   Reply With Quote
Old 01-16-2019, 08:22 AM   #3
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in Crisfield, MD
Country: USA
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 6,820
It may be my imagination, but it looks like there is some corrosion on the terminals. Any chance of moisture having gotten in there?

An important thing to understand about your Magnum Energy inverter / charger is that regardless of the state of charge, it always goes to full power output charge when turned on, and then sort of quickly reduces to the correct charging amperage. That initial spike along with some terminal corrosion may have been what welded the contacts closed in the circuit breaker.

Regarding circuit breakers, remember that the point at which they thermally trip is a function of time and amperage. It takes a much higher amperage (maybe more than double the rated amperage) to near instantly trip a breaker. A smaller over amperage can take minutes to trip. Fuses are usually instantaneous at a percentage above rated amperage.

Ted
__________________
Blog: mvslowhand.com
I'm tired of fast moves, I've got a slow groove, on my mind.....
I want to spend some time, Not come and go in a heated rush.....
"Slow Hand" by The Pointer Sisters
O C Diver is offline   Reply With Quote
Old 01-16-2019, 08:41 AM   #4
Guru
 
djmarchand's Avatar
 
City: Litchfield, Ct/Punta Gorda, Fl
Country: USA
Vessel Model: Atlas Pompano 23- outboard
Join Date: Aug 2012
Posts: 4,409
That black wire that goes off to the left of the picture sure doesn't look big enough to carry 30 amps safely. NEC requires 10 gauge for 30 amps although the ampacity of 14 gauge, which it looks like, is 35 amps. That wire looks like it got quite hot but didn't melt in two proabably because it went horizontal from the source of the heat, not vertical like the big one. Heat rises.



I suspect as others have speculated that there was a corroded connection which heated the wire until it melted.


I should note that the inverter/charger can pull more than 30A AC. When connected to shore power it can pull about 15 amps for its 100A charger but the pass through relay can pull whatever the circuits it supplies are demanding. That is why you have a 30A breaker supplying the inverter/charger of course.



Another other question is how much current does the small wire pull? The combination of the big and small wire could be more than 30 amps, but that begs the question as to why the breaker didn't trip.


In any case I would replace the breaker, fix the burn wire and figure out where the small wire goes.


David
djmarchand is online now   Reply With Quote
Old 01-16-2019, 08:53 AM   #5
Guru
 
tiltrider1's Avatar
 
City: Seattle
Country: USA
Vessel Name: AZZURRA
Vessel Model: Ocean Alexander 54
Join Date: Aug 2017
Posts: 1,188
A loose crimp could easily be the cause. Untinned wire that’s 30years old could easily develop enough corrosion to have caused the problem. Undersized wire with a little of the above could cause the problem. None of these issues would trip the breaker. The issue is heat not amperage.
tiltrider1 is online now   Reply With Quote
Old 01-16-2019, 09:04 AM   #6
CMS
Senior Member


 
City: Casco Bay
Country: USA
Join Date: Feb 2016
Posts: 206
Pretty impossible to tell from a distance, and one image, without seeing more. From where I sit, based on what I can see, I would have to say high resistance due to improper crimping techniques/tooling as well as the potential issues below.

That terminal also suffers from incorrect terminal/lug stacking meaning the highest loaded terminals always goes on the bottom and smaller loads go on top. That high load terminal is stacked on a red terminal, likely for an indicator lamp, meant to carry just a few amps at best. This is backwards..

The hot wires in the background also don't appear to be 10GA. This too can create high resistance.

We really need to know more about how this inverter charger is physically wired...

All the above said the melted black wires in the background may change everything and this could also be a dead short.......
__________________
-CMS

MarineHowTo.com
CMS is offline   Reply With Quote
Old 01-16-2019, 09:11 AM   #7
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 4,998
A high resistance connection due to bad crimp or loose screw or whatever will make heat enough to melt things even with amps well below breaker setpoint. Eventually heat conducts into breaker and trips it on thermals, but sounds like you caught it before that happened.
Ski in NC is online now   Reply With Quote
Old 01-16-2019, 09:36 AM   #8
Guru
 
High Wire's Avatar
 
City: Cape May, NJ and Englewood, FL
Country: USA
Vessel Name: Irish Lady
Join Date: Dec 2007
Posts: 2,581
Agree with bad crimp/ high resistance heating. The copper at the crimp appears melted! The breaker will not trip in those cases. Consider yourself lucky that nearby materials did not ignite. The little wire would typically be the feed to an indicator light or a voltmeter.
So the question is who worked on that terminal last and what else did they do? As a minimum the white and green wires of that cable plus the connections on the other end are questionable.
Those little infrared cameras that plug into a smart phone could have easily spotted this problem long time before failure.
__________________
Archie
1984 Monk 36 Hull #46
Currently in Cape May, NJ
High Wire is offline   Reply With Quote
Old 01-16-2019, 10:02 AM   #9
Guru
 
C lectric's Avatar
 
City: B.C.
Country: Canada
Vessel Name: Island Pride
Vessel Model: Palmer sedan 32'
Join Date: Oct 2007
Posts: 2,368
I'll fourth/tenth whatever that the problem was mis-stacking/ poor crimps/ loose connection.

I've seen that many times before. The breaker may not trip because the actual current was not an overload current. The heating may or may not make it to the breaker mechanism. Also depends upon the C.B. type although yours should be a thermal type but check.

Check your other C.B. connections.
C lectric is online now   Reply With Quote
Old 01-16-2019, 11:33 AM   #10
Guru
 
Xsbank's Avatar
 
City: Pender Harbour, BC
Country: Canada
Vessel Name: Gwaii Haanas
Vessel Model: Vancouver Shipyards Custom Aluminum 52
Join Date: Sep 2013
Posts: 3,114
Apart from the wiring issues as noted above, what is your total load? You are supposed to only load your shore power to 80% of its capacity which would be about 2800 watts. Anything over that and the voltage begins to drop and the temperature rises in the circuit. You are lucky you didn’t burn up. Look at your shore cable - is it pristine? Any condition less than perfect will cause resistance and lower the amount of watts you have available causing your situation to occur at even lower loading. Heater? 1500 watts. Water tank? Same. Lights? TV? Oh right, a giant inverter...no wonder it baked.

Many assume that you can load the system until the breaker pops, then back off. WRONG! Stick your multimeter in a wall socket and measure the voltage. Even one volt less than what’s on the dock pedestal means you are OVERLOADED.

Circuit breakers are designed to protect against shorts, not overloading. If there is enough heat the breaker MAY pop but don’t count on it. Add in the generally crappy workmanship of wiring on many boats, installed by ignorant owners...

Doesn’t anybody do searches anymore? I’m even annoying myself at having to repeat all this over and over. 30 amps is a minuscule amount of power and you are VERY LIMITED in your ability to use it. Or ignore all this and lose your boat or burn up a marina or die. That’s it.
__________________
Don't believe everything that you think.
What are we offended about today?
Xsbank is offline   Reply With Quote
Old 01-16-2019, 12:16 PM   #11
Senior Member
 
BrianSmith's Avatar
 
City: Wherever Smartini is
Country: USA
Vessel Name: Smartini
Vessel Model: 2002 Kristen 52' Flybridge Trawler
Join Date: Mar 2014
Posts: 315
Click image for larger version

Name:	Fried CB.jpg
Views:	65
Size:	25.4 KB
ID:	84317

Summary:
1. The small wire's ring terminal was the closest one to the CB post, which it should not have been. (I corrected that when I rewired.) However, it's probably been like that for the entire 2 1/2 years we've owned the boat.

2. I can't attest to the crimp on the wire, since both parts are now totally destroyed.

3. The screw through the ring terminals into the posts was tight. Very tight.

4. There was no moisture involved. This is in the saloon, and it's dusty dry inside/behind the electric panel.

5. I'm 99% sure there was no corrosion at the junction of the wires / crimp / ring terminals / post, because there's none anywhere else in the whole panel area, and it would require moisture to be corroded - see #4.

6. I replaced the breaker and made all new, solid connections and turned everything back on. When the charger came on, it went into Bulk mode as expected, and the temperature of the terminal that had fried rose about 2 degrees F and has stayed there for 15 minutes.

7. We don't run much through the inverter: a small AC fan or two, the wifi system (2-3 amps), and the TV/stereo. We never run the microwave or any heating device through it.

8. The wire that burned - the one that carries the current to the battery charger - is 10ga, which is one size bigger than the Magnum installation manual says to use.

Based on everything that everyone has said, and that I have observed, the most likely cause seems to be a faulty crimp in the fried wire, or a faulty circuit breaker that allowed the heat to build to the fry point, and that then fried the attached wire.

I'll be keeping a close eye on this, for sure, but for now, it all seems back to normal. (I should probably install a smoke detector in the open space behind the panel - that would alert me to something like this faster than anything else I can think of.)

As always, thanks, TF, for the great input!
BrianSmith is offline   Reply With Quote
Old 01-16-2019, 12:56 PM   #12
Guru
 
Xsbank's Avatar
 
City: Pender Harbour, BC
Country: Canada
Vessel Name: Gwaii Haanas
Vessel Model: Vancouver Shipyards Custom Aluminum 52
Join Date: Sep 2013
Posts: 3,114
What's that giant battery cable on the other end? Are you sure that's dock power? 120V?
__________________
Don't believe everything that you think.
What are we offended about today?
Xsbank is offline   Reply With Quote
Old 01-16-2019, 01:32 PM   #13
Senior Member
 
BrianSmith's Avatar
 
City: Wherever Smartini is
Country: USA
Vessel Name: Smartini
Vessel Model: 2002 Kristen 52' Flybridge Trawler
Join Date: Mar 2014
Posts: 315
Quote:
Originally Posted by Xsbank View Post
What's that giant battery cable on the other end? Are you sure that's dock power? 120V?
That's the 120V in from the shore power / generator selector switch. Yes, I'm sure.
BrianSmith is offline   Reply With Quote
Old 01-20-2019, 04:23 PM   #14
Guru
 
City: Seaford Va on Poquoson River, VA
Country: United States
Vessel Name: Old Glory
Vessel Model: 1970 Egg Harbor 37 extended salon model
Join Date: Jan 2016
Posts: 1,895
If the wire further away is ok, not burnt, then it failed due to high localized heat due to high resistance connection. I suppose the internals of the breaker could also corrode. But most likely it was bad wire connection, either to the lug screw or the crimp. Likely was failing and heating up for a long time, and those heat cycles will make bad connections worse over time, so it just could not cope anymore, and fried itself.
sdowney717 is offline   Reply With Quote
Old 01-20-2019, 04:43 PM   #15
Guru
 
kchace's Avatar
 
City: Brookline, NH
Country: USA
Vessel Name: Blue Heaven
Vessel Model: Albin 43 classic double cabin, twin 135 Lehmans
Join Date: Sep 2013
Posts: 1,367
Quote:
Originally Posted by sdowney717 View Post
If the wire further away is ok, not burnt, then it failed due to high localized heat due to high resistance connection. I suppose the internals of the breaker could also corrode. But most likely it was bad wire connection, either to the lug screw or the crimp. Likely was failing and heating up for a long time, and those heat cycles will make bad connections worse over time, so it just could not cope anymore, and fried itself.

This ^^
kchace is offline   Reply With Quote
Old 01-21-2019, 07:52 AM   #16
Senior Member
 
BrianSmith's Avatar
 
City: Wherever Smartini is
Country: USA
Vessel Name: Smartini
Vessel Model: 2002 Kristen 52' Flybridge Trawler
Join Date: Mar 2014
Posts: 315
Quote:
Originally Posted by sdowney717 View Post
If the wire further away is ok, not burnt, then it failed due to high localized heat due to high resistance connection. I suppose the internals of the breaker could also corrode. But most likely it was bad wire connection, either to the lug screw or the crimp. Likely was failing and heating up for a long time, and those heat cycles will make bad connections worse over time, so it just could not cope anymore, and fried itself.
Yep, that is the conclusion I have reached. Thanks, all, for your input!
BrianSmith is offline   Reply With Quote
Old 01-21-2019, 11:39 AM   #17
Guru
 
City: Fairport
Country: United States
Join Date: Jan 2017
Posts: 1,405
Quote:
Originally Posted by Xsbank View Post
...

Many assume that you can load the system until the breaker pops, then back off. WRONG! Stick your multimeter in a wall socket and measure the voltage. Even one volt less than what’s on the dock pedestal means you are OVERLOADED.

Circuit breakers are designed to protect against shorts, not overloading. If there is enough heat the breaker MAY pop but don’t count on it. Add in the generally crappy workmanship of wiring on many boats, installed by ignorant owners...

Doesn’t anybody do searches anymore? I’m even annoying myself at having to repeat all this over and over. 30 amps is a minuscule amount of power and you are VERY LIMITED in your ability to use it. Or ignore all this and lose your boat or burn up a marina or die. That’s it.


Amps are a continuum of coulombs per second. The word "short circuit" is simply a layman's way of saying "much higher than usual current". Marine breakers contain an element of thermal sensing for small excursions beyond the breaker rating, and a magnetic element that has a much faster operate time for "much higher than usual currents".
diver dave is offline   Reply With Quote
Old 01-21-2019, 11:59 AM   #18
Guru
 
Comodave's Avatar
 
City: Au Gres, MI
Country: US
Vessel Name: Never Say Never
Vessel Model: President 41 DC
Join Date: Jul 2015
Posts: 3,662
Having had this problem once, a survey of the complete electrical system would probably be a good idea.
Comodave is online now   Reply With Quote
Old 01-21-2019, 05:43 PM   #19
Senior Member
 
Jay N's Avatar
 
City: Edmonds, WA
Country: USA
Vessel Name: WESTERLY
Vessel Model: 1974 Pacific Trawler 37
Join Date: Oct 2007
Posts: 427
Thanks to this thread, I moved up my annual electrical panel and circuit breaker inspection.



After loading the generator to max (40A) by turning all the heavy AC loads, and after about 15 minutes, I take my heat gun and shoot everything.


I'm mainly interested in terminal and circuit breaker temps, especially for high load circuits.



The first pic shows the temp (91F) for the water heater circuit breaker. The second pic shows the crimped connection temp (155F). The third pic shows the wire temp (100F) about 1" before the crimped connection. Talk about highly localized heat!



What you should know is that the circuit was wired new in 2009 with 12/3 when there was a 1000 watt water heater. This was replaced in 2015 with a 1500 watt water heater, but the #12 wire should have been ok if there had not been a weakness at the crimp.


So, after replacing the crimp: 1) Going to move the inspection schedule to every 6 months, and 2) give thanks to the heat gun. Again! Great tool!
Attached Thumbnails
Click image for larger version

Name:	IMG_1443.jpg
Views:	40
Size:	125.5 KB
ID:	84502   Click image for larger version

Name:	IMG_1444.jpg
Views:	41
Size:	123.6 KB
ID:	84503   Click image for larger version

Name:	IMG_1445.jpg
Views:	36
Size:	116.2 KB
ID:	84504  
Jay N is offline   Reply With Quote
Old 01-22-2019, 06:54 PM   #20
Senior Member
 
Jay N's Avatar
 
City: Edmonds, WA
Country: USA
Vessel Name: WESTERLY
Vessel Model: 1974 Pacific Trawler 37
Join Date: Oct 2007
Posts: 427
Here's a followup to the previous hot crimp post after installing a new crimp and 15 minutes of water heater load.

The removed crimp appeared ok, but the terminal connection was slightly loose. This allowed an elevated temp that eventually melted the glue in the heat shrink, which flowed into the loose connection causing a further elevation in temp caused by a reduction in connection quality. The 105C rated tinned wire was in good condition.

Caught it early enough to prevent more serious consequences.

Put a screw driver/wrench on every connection behind the circuit breaker panel, this was the only one that was even slightly loose.


As before, the first pic is of the circuit breaker body, the second of the crimped connector, the third of the wire about 1" before the crimp.
Attached Thumbnails
Click image for larger version

Name:	IMG_1447.jpg
Views:	33
Size:	134.7 KB
ID:	84529   Click image for larger version

Name:	IMG_1448.jpg
Views:	31
Size:	147.7 KB
ID:	84530   Click image for larger version

Name:	IMG_1449.jpg
Views:	31
Size:	140.4 KB
ID:	84531  
__________________

Jay N is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 10:26 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012