Just About Lost the Shop and Everything in it.

A couple days ago I thought I smelled plastic burning in the shop but ruled it out thinking the neighbors are outside burning rubbish AND everything was working fine in the shop. Today my compressor quits and I am thinking the worst that I need a new one. Checked the compressor out and everything looked good. While checking the shop power panel I discovered this mess, what the hell causes this ****? Now that I think back over the last 15 years I remember replacing smaller breaker that did the same thing but just to themselves never melting the buss bars..........
Why didn't a breaker kick off?
I guess the moral is trust your nose!

 

That could have been really bad. Luckily nothing did... Ha ha we should listen to ourselves. Lucky u

 

Sometimes they just weld themselves shut inside. Glad you caught it before a major deal.

 

wow that was a close one. got me worried as my garage was wired by amateurs.

 

It is not uncommon for screws to loosen up in an electrical box. Once this occurs you can cause damage to the buss bar. The heat the the loose connection had could distort the metal making future problem more likely. Also the heat can cause circuit breaker to go bad. Recommend that everyone have their electric box serviced once a year.

 

Looks like there was a poor connection between the CB and the bar. If it were me, I would be removing ALL the CBs from that box and checking the condition of the connections on each of the CBs. Glad to see that you dodged a bullet!

 

Why didn't a breaker kick off?


I'm guessing it might off not tripped because you did not have a over-load or a short condition sometimes what happens with breakers is they loosen up due to dissimilar materials used in the buss and breaker, they arc more when they heat up,, over the long run you will be faced in replaceing the panel.

 

Very Lucky..

 

We had a porch light go because an earth come loose and made contact across the terminal. Made a big black smoke mark- I reckon like this one we were lucky- the whole roof could've gone up.
This happened on a dry & very windy day. Heard a lot of emergency sirens that day.
So yes I think regular maintenance schedules as has already been stated is a wise thing. Also a good big RELEVANT fire extinguisher.

 

The breaker did not trip because it only protects the wire on the load side of the breaker. The loose connection occured on the line side of the breaker before it p***ed through the breaker. The spring that holds the breaker tight to the bus was loose causing arcing between the breaker and the buss. Continual heating and cooling due to overloading a circuit can cause the spring to lose its tension over a period of time.
One thing to remember is that residential breakers are not rated 100 percent continuous duty. They should only be loaded about 80 percent.

 

i see this problem at least twice a week,usually it comes from using incorrect breakers,i noticed in your pictures you have different type and different manufacturers breakers in your panel,the way these fit onto the bussing is different on almost all applications,you need to use the type specified and the make that matches your panel...

 

I had a 100 amp breaker fry without tripping
I think it was lightning

 

Put me in coach!!! I can do this one!!!
Been makin a living as an electrician since 1987 so finally a post I actually have some experience with.
All of the above post mention valid reasons... dissimilar metals eventually loosen/develop corrosion and heat up, even without an "overload" condition on the circuit. Lots of mobile homes builtin the '70s with aluminum wiring on copper switch and recep terminal screws had issues like this.
Contacts can get "welded" in the breakers.
The one thing I will say... CLEARLY.....and I don't give a **** who flames me for it..the post above is in my book "gospel"

If that is a Federal Pacific Panel.....DITCH IT!!!!!!!!!

I have seen F.P. breaker with a measured amp load on them that was double the rated trip. Amp probed it myself.
I can't count the number of breakers and panels ( F.P.) I have seen that looked just like that.
Seriously.... you need to have that panel changed out. We refer to F.P breakers as "never-trips".
Meanwhile.....check each breaker.... if possible, turn off the Main and clean the buss bar. ------DO NOT do this if you are not able to turn off the power to the panel. I would not tell the average homeowner to do this but you say you have swapped breakers before so I ***ume you know your way around a panel.------- you can s****e them, use a little piece of emory cloth or sandpaper, ect....Then, check the breaker itself,clean it up too, make sure when you put it back the screws are tight holding the wire into the breaker.
Can't really tell in the pic, but it looks like that slot is toast on your panel. It appears the buss bar tab has been burned off.
If you called me out on a service call I would be reluctant to let that panel stay in service.

 

That is enough to make me consider using a commercial box with BOLT IN breakers. It would be a relatively small upgrade (probably about $60 to $100 more for box and breakers) when you consider that you need to replace the box anyway.

The breakers would not "trip" because the issue was "upstream" of the individual breaker, and the resistance was not near enough to trip the main.

There are some areas of an electrical system that are relatively unprotected and are more or less ***umed to be "right". The bus bars fall into this category.

 

It's not Federal Pacific.

Judging from the neutral bus it's not that old of a panel either. The printing on breakers looks like stuff made in the last 5-10 years.

Cheap junk that is made nowdays - 1" thick standard breakers - could be Murray, Siemens, or similar.

If you want the best install Square D QO (not Homeline from China Depot) panelboard. NQOD for bolt on breakers but not reallly needed.

As previously noted the poor contact combined with a heavily loaded circuit will cause the spring loaded clip to fail and burn up the busbar.

 

when we take into effect the cost of everything that means anything to us, a panel change is cheap!!! I have bought and completely remodeled two houses. and the first thing I do is swap out the box. no less then a 200 amp service!!!.

 

It was a poor connection that started arcing. Like others stated, it was not an overload or short situation that would couse it to trip. Also, this can happen to any maufacturers box including Square D. Corrosion can also cause this. I use di-electric grease to help reduce corrosion.

 

Pat yourselves on the back, all these great post and not one flame!
Just to add more drama to the problem my big parts cleaner is directly below the panel. Tomorrow both the panel ANS the parts cleaner will be replaced moved.
Now how do I kill the power to the mains coming in without calling PUD or cooking my meeeeeeene?

 

Your not using your breakers as switch's are you. I've seen them go bad when used that way to. Go Square D on panel and breakers.

 

This had nothing to do with a loose screw. The arc was BEFORE the breaker, meaning that the main was the only OCPD in the circuit, and 200A is a lot of juice, enough to cause this kinda damage. As far as annual servicing on your electrical panel...well, that just seems a bit silly to me.

To the OP: are you using the right breakers for your box? Now before you get in a huff hear me out. There are aftermarket breakers available that might snap into a box and seem like they are working hunky dory, but in reality they may provide a loose or poor fit to the buss, that would go a long ways to explaining what happened here. Also, if the wires that terminate into the breaker are causing the breaker to be under tension (putting pressure on the breaker) it will cause the connection to loosen over time.

Federal Pacific, be thankful it wasn't a Zinsco, their motto is "Buy a Zinsco, it'll never trip!"

 

+1 on this. I know a lot of people do it and it ain't right.

Another thing everone can do is once and a while open the cover on your panel and feel the surface of the breakers. They should be room temp. If they are warm to the touch, you are getting close to what happened to the OP.

 

anybody got extra square d "xo" style breakers????? PM ME

 

scary stuff...

 

Wow that could have been and arc flash disaster.....glad you found it without getting burned..

 

This panel has given me so much trouble I don't even keep the panel door on it, been years.
Yes, I do use the breaker as a switch on some things and my compressor is one. Once several years ago I left for a fishing trip, when I go home my compressor was running because of a broken air line and very hot, hard to tell how long it was running. Since it's outside it's easier to flip the CB at night and when I leave out of town.
The name on the panel looks to be " ElectriCenter" I was told that the CB were no longer made so threw the years I have mixed matched CB that Home Depote or Lowes has said would work.
In short I am guilty of all that you guys have said could be wrong, "multiple wrongs instead of just one".
This has opened my eyes big time as my shop is full of customers rides and none "cheap" or insured under my home owners ins.
I read every post, thanks to all it comes out tomorrow and will find a Square D with Square D CB .................

 

Just remember that anything you buy at the "Big Box" stores (Depot, Lowes, etc...) is going to be the cheapest product the manufacturer can get away with selling.
It's a real bite in the wallet, and a pain in the dingding, but get yourself to a good electrical supply house.

Good luck, and let's all be grateful this wasn't a tragedy.

 

man you have gotin lucky, guess i need to look at both my boxes and check them out

 

That coulda been a whole lot worse! I agree though that you should probably go through the whole panel and tighten things up or replace the whole things!

 

Glad you got out lucky on that. Replace the whole damn box and smash the breakers you have before tossing out.

When I built my last place I priced out boxes and breakers. Sadly (cough) it was actually good bit cheaper to open an account at the local contractor electrical supply and use all commercial grade Square D. No tax id? Use a freind!

They had every damn thing I needed in stock like a damned candy store. Oh and one trip and out the door unlike Culowes or Home De'pot.

 

Glad to hear you're taking this seriously. Whatever brand you go with make sure it is a major one. I've only recommended Square D and Cutler Hammer to people I know, no sense in screwing around with anything else.

Hire yourself a good electrician too, not the "Git-R-Done" guys I'll also second going to an electric supply shop, they'll be able to get you what you need without the b.s. (That home depot "expert", well, usually isn't). There should be a Platt somewhere near you, they've always done me right.