Recurring main breaker MELTDOWN!!! any ideas???

[420Gator]

so im about to start another run so i decided to tighten all my electrical connections and found my main breaker has been melted again. i have a collection of these now all melted and none of them ever flipped once. whats the deal here, why arent the breakers tripping? hopefully someones experienced something similar

 

[420Gator]

oh yeah this one was actually still working before it was removed

 

[Underground]

I would say your buses are bad from a previous bad main. The high resistance connection is heating up and melting your breakers. First one probably went bad from corrosion. Possibly from a humid basement or from water running down your service entrance cable. It usually drips right on the main. Look for white powder on the bare alu on your service entrance cable, try to look where it would drip from if water was traveling through the cable from the meter. This is one of the reasons I would rather use a dry type connector on the bottom of a meter. That way it can drain instead of build up and go down the cable. They even have drain holes in the bottom rear of the meter sockets. Yet we are required to basically form a funnel with a weatherproof connector!

 

[Buddy Hemphill]

Is the wire getting hot?

 

[Papa]

Underground's got it.
i'll try to help by restating.
if i'm seeing that photo correctly, it's melted around the connection to the busses.
that suggests the busses are heating up (not the wire side).
that suggests that there is a restriction in the electrical flow somewhere upstream of your breaker. (the friction of the electrons moving through this restriction creates the heat).
so, that restriction could be a loose connection (like cable to buss bar connection) or corroded metal as Underground explains.

you gotta find where that high resistance connection is and get it fixed,

its a fire danger that only gets worse.





Papa

 

[Underground]

As far as not tripping, it could be a few different reasons. In general, a breaker trips one of two ways.
Thermally When a bi-metallic strip heats up enough, due to the load on the circuit, it will trip the breaker.
Magnetically When there is a dead short on the circuit.

Ambient temperature not only effects load capacity, but increases or decreases sensitivity of devices designed to work within a certain temperature range.

My opinion is that it probably should have tripped given the heat that was created by the bad connection. It could have been that your buses and service entrance cable were acting as a heat sink. But, the breaker was not designed to trip under the conditions that caused this. I have seen and repaired many that did not.

Is this an actual main, or a back-fed branch circuit breaker? An actual main breaker is bolted in the panel as required. Some people will back feed a branch circuit breaker in a main lug only panel and call it the main. Your main breaker carries the entire load of the panel. If some genius installed the wiring in such a way that the wire is applying force to the breaker and this is a back-fed branch circuit breaker, it's very easy to see why it did this in the first place.

You are just rolling the dice every time you re-install a new breaker without replacing damaged buses and wiring if needed. When the wire is heated beyond it's designed limits, the characteristics of the wire is changed. It becomes brittle and hard and is no longer capable of carrying the load it was designed for, as well as becoming a fire hazard. Many times the existing wires can be cut back beyond the damaged section if slack is available, or can become available by re-routing the cable assembly.

It's always best to use a panel with a main breaker, even if it is just a sub panel. Main breakers and branch circuit breakers are designed differently. Main breakers have a higher AIC rating. AIC stands for ampere interrupting capacity. It's the capacity at which the device can open and extinguish the current arc without causing damage to the device.

When a short is created, the voltage in the circuit drops towards 0 volts as the current proportionally increases. The maximum fault current available depends on the source. If the house or building is fed from 25KVa transformer, then theoretically there are 25,000 amps that can instantaniously run through any circuit under fault conditions. The breakers job is to open the circuit before this happens.

This is why sometimes a main will trip even though the branch circuit didn't. Sometimes the branch circuit can trip, but the current has reached a point over the branch circuits aic rating and an arc is produced from one contact to the other and the current continues to flow from one contact to the other through the air.


To make a long story short, replace the panel and any wire damaged.

 

[Seamaiden]

S'cribed, this is scary as shit!

 

[420Gator]

i have a sub but this is off the main. the wierdest thing is when i first started growing i had 8 lights and lots of ac running with no probs, now i only have 2 1ks going, no ac and just a handfull of small household items. damn im renting and dont wanna come out of pocket to replace the panel but that may be my only option. fuckin cheap ass house with 100a main. i probly need to upgrade anyway

 

[420Gator]

S'cribed, this is scary as shit!

it is scary shit

 

[Underground]

i have a sub but this is off the main. the wierdest thing is when i first started growing i had 8 lights and lots of ac running with no probs, now i only have 2 1ks going, no ac and just a handfull of small household items. damn im renting and dont wanna come out of pocket to replace the panel but that may be my only option. fuckin cheap ass house with 100a main. i probly need to upgrade anyway

If the mating surfaces have been compromised, your surface area is not sufficient to carry the load. It could be a 200 amp breaker, but if the connection has been compromised it may only be able to carry 20 amps. If you're drawing twice that you are still well under the ampacity of the breaker but could be double what the compromised connection is capable of carrying.

Def go for the upgrade. SE and entire panel will get replaced. Just tell your landlord that you spoke to an out of state friend or relative that is an electrician and they told you that you can no longer replace the breaker due to damage to the buses and possible damage to the service entrance conductors.

 

[420Gator]

thanks for the help underground much appreciated. ive got someone who will do the install for 300 and im finding panels online for just over 100 plus all the new breakers. how sure are u its not anything outside the panel? i dont wanna have all this new shit put in and have the same thing happen a few weeks later

 

[420Gator]

Underground's got it.
i'll try to help by restating.
if i'm seeing that photo correctly, it's melted around the connection to the busses.
that suggests the busses are heating up (not the wire side).
that suggests that there is a restriction in the electrical flow somewhere upstream of your breaker. (the friction of the electrons moving through this restriction creates the heat).
so, that restriction could be a loose connection (like cable to buss bar connection) or corroded metal as Underground explains.

you gotta find where that high resistance connection is and get it fixed,

its a fire danger that only gets worse.





Papa

By upstream do u mean this could be edisons fault?

 

[Underground]

thanks for the help underground much appreciated. ive got someone who will do the install for 300 and im finding panels online for just over 100 plus all the new breakers. how sure are u its not anything outside the panel? i dont wanna have all this new shit put in and have the same thing happen a few weeks later

I'm pretty sure.

And by upstream, he's saying the problem is before the breaker in the circuit. In this particular case, your problem was where the breaker and buses meet.

Get some of this click here
I use this for everything! Like it way better than that gray crap and it can be used on copper too.

 

[420Gator]

I'm pretty sure.

And by upstream, he's saying the problem is before the breaker in the circuit. In this particular case, your problem was where the breaker and buses meet.

Get some of this click here
I use this for everything! Like it way better than that gray crap and it can be used on copper too.

so what if i took the breaker off and sanded down the bus bar?

 

[Underground]

so what if i took the breaker off and sanded down the bus bar?

If I was to do something like that.....I would use fine sand paper, make sure buses were still thick enough and apply some of that stuff I linked to on the buses. I would only do this after I knew I was able to reuse the existing conductors. I would bend them near the terminations. If they were stiffer than normal or I heard crackling I would move up the wire until I found where the wire was no longer affected. Then I would make sure that the breaker was wired in such a way that it would not apply any pressure to the breaker. If it wasn't bolted down, I would get a bolt down kit if available for that panel. Then I would check the connection point with an ir laser temp gun. Being a 100 amp breaker it has to be at least 75*C rated. I'd make sure connection point doesn't get much if any higher and make sure it stabilized around that area. I'd do so by checking and logging the temperatures every 15 minutes or so as I brought the load up. Then I would probably check it once an hour for at least 8 hours. If it was getting too hot, I would probably cut back the load until it was in an acceptable range so that I could keep things partially running until I could fix it right.

But that's just what I would do. I'm a professional and would recognize dangers or warning signs that others would not. There are always variables.

 

[420Gator]

thanks again. i may just take all the breakers off and clean everything and also have the leads replaced, theyre some kinda cheap thin non-flexable tin tabs coming from the meter not even real wires. then when i put em back ill change thier position to a place that hasnt had multiple breakers melt on it...... does it matter where the main breaker is located on the bus?

 

[hiboy]

That Main breaker looks, as far as the photo shows, a normal design breaker. If you are trying to save money as stated you might be able to insert it in another undamaged slot
( if you dont have a dedicated main breaker slot ) and not have the resistance/ heat factor as you have. Ug and papa are right on about the damaged buses. Sometimes you can smooth the buses out but that isnt the best choice. Wouldnt do that though by looking at that thing. Dont you love the smell of that thing.
Good luck

 

[Papa]

i had something just like this happen once. it was a loose connection (loosened up after about 75 years) of a buss bar. we identified exactly where the problem was by following the heat, it lead us to the point where the heat was being generated.

and no, by "upstream" i mean towards edison's end, but i think we're all thinking that the problem lays between your service drop (where edison's responsibility ends) and your breaker.

 

[Underground]

thanks again. i may just take all the breakers off and clean everything and also have the leads replaced, theyre some kinda cheap thin non-flexable tin tabs coming from the meter not even real wires. then when i put em back ill change thier position to a place that hasnt had multiple breakers melt on it...... does it matter where the main breaker is located on the bus?

Hmmm take a pic of it, the only thing I can think of that you could be describing shouldn't be being used in this case.

 

[hiboy]

that cheap tin is your supply from meter to main. in a
200 amp panel its actually almost the size of an L bracket.. sounds like yours i s really small... probably whats creating the heat. what name of part are you thinking of ug>?