Behavior of Joule Heating in few contact points terminals and arcing

[tersh]

I don't think your incident should effect the choice of DIN vs plug on breakers. Forgive my heartless words that are about to follow- but if you play stupid games you will win stupid prizes. The stupid game is working live. The prize is fire, arc flash, down time, ruined equipment and starting over. Never work live unless you have proper PPE- and even then don't do it unless you want damaged equipment. Yes I know in the US electricians work live all the time, but you will also hear countless stories of falling off of ladders, blowing holes in tools, ect.

After that incident. I had fright of live wires. And I never handled them myself. I even got concerned when electricians were going to touch it. So for any repairs. I made it a point to make sure the utility company shuts down the power first. I know the consequences of it. Actually the electricians wanted me to be liable. But the architect and electrical contractor talked them out of it and they paid them for treatment. And I avoid meeting them afterwards because they wanted to show me the scars and pay them. So I'll make it will never happen again because of that traumatic experiences.

I doubt that a new breaker would flash over from carbon deposits. My honest opinion is that the electricians aren't telling you something and much more took place then terminals being hooked up to a breaker in the on off position.

Well I had keys to the service entrance panel. So everything done there I was always present to watch it. The whole incident when the panel was opened and touched, I was besides them watching it making sure they wont short the phases or panels. And I really saw it was simply live wires being hooked to the terminals in off position just like I described.

But in any case it is certainly possible for a short circuit to burn skin and cause blisters, as well as the sparks and molten metal igniting clothing and burning what ever it comes in contact with.


Were those the service conductors he was hooking up? In that case a short circuit will take its time clearing, if ever. POCO wires should always be treated as unfused because sometimes they literally are.

The feeders he was hooking from was the service meters directly.

In US residential. When there is a dead short in the service entrance panel. It is also the results? Burn and blisters inches away?

I think minor arc flash always occurs from any short. So the initiating factors in my case was whether it was caused by carbonized particles or dead short. But just the same, there is arc flash?

Or do you reserved the term arc flash only for those meters wide arc blast in industrial panel? If so. Then what is the term for residential flash? Maybe short flash, or arc from short, what? What are they officially called by NEC?

 

[mbrooke]

After that incident. I had fright of live wires. And I never handled them myself. I even got concerned when electricians were going to touch it. So for any repairs. I made it a point to make sure the utility company shuts down the power first. I know the consequences of it. Actually the electricians wanted me to be liable. But the architect and electrical contractor talked them out of it and they paid them for treatment. And I avoid meeting them afterwards because they wanted to show me the scars and pay them. So I'll make it will never happen again because of that traumatic experiences.

Well, give it time. Hopefully one day that will change.

Well I had keys to the service entrance panel. So everything done there I was always present to watch it. The whole incident when the panel was opened and touched, I was besides them watching it making sure they wont short the phases or panels. And I really saw it was simply live wires being hooked to the terminals in off position just like I described.

Ok- but its hard for me to figure out why two terminals are scorched and how they were somehow bridged.


To me it looks like the breaker was on, and when the electrician inserted the wire into the last terminal there was a huge spark from an overload or short downstream. This scared him and the wire then came crashing into the middle screw shorting that out as well. But take that with a grain of salt.

The feeders he was hooking from was the service meters directly.

In US residential. When there is a dead short in the service entrance panel. It is also the results? Burn and blisters inches away?

It can certainly be if the short circuit current is high enough.

I think minor arc flash always occurs from any short. So the initiating factors in my case was whether it was caused by carbonized particles or dead short. But just the same, there is arc flash?

Correct, any short will cause a flash. The more current the bigger and more violent the flash. The longer it takes to clear also adds to the incident energy.

Or do you reserved the term arc flash only for those meters wide arc blast in industrial panel? If so. Then what is the term for residential flash? Maybe short flash, or arc from short, what? What are they officially called by NEC?

I believe arc flash. Though the NEC isn't really as concerned about it as OSHA.

 

[tersh]

Well, give it time. Hopefully one day that will change.




Ok- but its hard for me to figure out why two terminals are scorched and how they were somehow bridged.


To me it looks like the breaker was on, and when the electrician inserted the wire into the last terminal there was a huge spark from an overload or short downstream. This scared him and the wire then came crashing into the middle screw shorting that out as well. But take that with a grain of salt.

It was in off position (we were sure of it because that's what we were focusing on the whole time along with the main event). I remembered clearly the moment the electrician was lowering the live wire to the terminal because it shorted earlier. So they added so many cardboards to make sure it wouldn't happen. And all our eyes were on that moment when the live wire touches the terminal. It arc flashed just as we feared.

In days ahead. I'll go to the arc flash resources and ask the most experts of them, the Mike Holt of Arc Flash akin to our Mike Holt of "Grounding and current doesn't go to ground but to source" thing. I'll ask what would happen if a small amount of carbon particles were in their industrial panel breaker, would it initiate a huge arc flash like the following:

I'll share with you when they have definite proof whether it can cause that or not. And the comment from the most expert of Arc Flash in the whole world.

Also I'll learn from the experts how to actually compute in detail the incident energy and source, load impedance and short circuit current and all because in the office building, the service panel was only 3 meters away from 75kVA transformers while at house, service panel was 30 meters away from 100kV transformer. I want to make sure cooking fumes won't cause arc flash in the house 125A Schneider din rail MCB main breaker. I don't take any chances.

It can certainly be if the short circuit current is high enough.



Correct, any short will cause a flash. The more current the bigger and more violent the flash. The longer it takes to clear also adds to the incident energy.




I believe arc flash. Though the NEC isn't really as concerned about it as OSHA.

 

[Russs57]

Carbon is conductive enough for arc flash. I have seen it happen.

 

[mbrooke]

But you said the breaker was brand new and it did not have any carbon on it?

 

[tersh]

But you said the breaker was brand new and it did not have any carbon on it?

Earlier in the day that fateful morning in 2015. There was a first short. The electrician didn't put any cardboard in the chassis so maybe the third live wire touched the chassis while he was inserting it into the last terminal? This deposited some carbon in the breakers. Actually this idea about carbon was an idea by a more senior electrician that time. But he said it was inside the breaker itself. That was why I preserved the breaker awaiting the day it can be opened. Finally I opened it today and there was no carbon inside. So it must be outside.

I wonder if small arc initiated by the carbon can chain react into much bigger arc many distances away. This was what I'll ask the arc flash guys how small a carbon can initiate how large an arc flash.

 

[mbrooke]

Earlier in the day that fateful morning in 2015. There was a first short. The electrician didn't put any cardboard in the chassis so maybe the third live wire touched the chassis while he was inserting it into the last terminal? This deposited some carbon in the breakers. Actually this idea about carbon was an idea by a more senior electrician that time. But he said it was inside the breaker itself. That was why I preserved the breaker awaiting the day it can be opened. Finally I opened it today and there was no carbon inside. So it must be outside.

I wonder if small arc initiated by the carbon can chain react into much bigger arc many distances away. This was what I'll ask the arc flash guys how small a carbon can initiate how large an arc flash.

How much carbon was on the case of the new breaker?

 

[Sahib]

I wonder if small arc initiated by the carbon can chain react into much bigger arc many distances away. This was what I'll ask the arc flash guys how small a carbon can initiate how large an arc flash.

It is due to vaporisation of metal including the carbon and subsequent expansion of the metal vapour into the surrounding space.

 

[tersh]

It is due to vaporisation of metal including the carbon and subsequent expansion of the metal vapour into the surrounding space.

Sahib. In the power plants or large industrial facility. If only very little carbon was deposited between the live terminals. Can it chain react into typical large arc flash? or would the carbonized particles vaporized before full arc is established.. or does the small plasma grow in size until the incident energy was used up in the arc flash?

mbrooke. I don't know how much carbon was deposited on the new breakers because the more senior electrician only mentioned about carbonized particles being conductive only after the second short so we didn't notice and I didn't even take picture after the first short (because who would have thought they would be another second short).

 

[tersh]

Will do, and trust me, I understand when you say its hidden :happyyes::happyyes:





Yes, you have the 1987 design I posted.






That might be it, the newer ones are assembled in the Dominican republic. On the side if you can find the pic, though you have to zoom in and turn your head:


https://www.homedepot.com/p/GE-Q-Line-20-Amp-1-in-Single-Pole-Circuit-Breaker-THQL1120/100356508








Share more Philippine panels if you have them. It is interesting for me to compare.

Here are examples of our locally produced panels. I was looking for one which can fit the Siemens GFCI breakers but they were kinda narrow:

Here is another local brand a bit wider:

This is bus bar from an older panel:

All of the bus bar stubs were not exactly 90 degrees aligned.

When I first saw the Siemens load center busbar. It's like seeing diamonds for first time. They sparkle and the bus bar are 90 degree aligned. I got it from amazon and shipping costs more than the unit. It's the only one that can perfect fit the Siemens GFCI breakers:

When ordering them. I included getting the regular Siemens 2-pole QP breaker to see how the spring clips are like. They fit perfectly the Siemens load center while the Siemens GFCI breakers have wider spring clips producing the gaps I shared before:

https://www.amazon.com/gp/product/B00002N5HJ/ref=ppx_yo_dt_b_asin_title_o03__o00_s00?ie=UTF8&psc=1


The regular Siemens 2-pole QP breaker is tested below in my original panel (the bottom breakers is Siemens, the rest are 1 pole GE breakers where only one of two poles can tripped as you said).

Why are Siemens regular breakers smaller than the GE, any idea? Are Siemens good in biting the bus bar too?

 

[romex jockey]

Anecdotally, i don't see a big 'fit' difference betwixt most major circuit breakers tersh, in fact i stock eatons universal breakers UL listed to fit most brands....

As to the causes of arc flash and/or arching, i would reffer you to the IEEE.

In either case, the devil is always in the details , which i applaude your tenacity of

~RJ~

 

[tersh]

Anecdotally, i don't see a big 'fit' difference betwixt most major circuit breakers tersh, in fact i stock eatons universal breakers UL listed to fit most brands....

As to the causes of arc flash and/or arching, i would reffer you to the IEEE.

In either case, the devil is always in the details , which i applaude your tenacity of

~RJ~

Well. Originally i planned to just plug in the Siemens 2-pole GFCI breakers to my original plug in panel. But someone wrote and warned me the following:

"The magic snap is not magic. Contact blades are not flat.

One thing you will notice about US breakers in matching panels is that they "Snap" in with a definite resounding snap. And when you try to remove them, the initial force needed to pull them out the first 0.1mm is considerably greater than the force needed to pull them the rest of the way.

That's because the bus bar in the service panel actually has a little "nub" shaped into it, of a specific shape. That shape engages matching curves on the breaker's spring clip. It works like a detent, creating the snap. However the good contact also creates a lot of mating surface area. As such, it runs at sane temperatures during high current flow, which is why UL approves it.

Every panel manufacturer uses a different shape of bus bar, requiring different shaping on the breaker's spring clip. They are different because of patents. Each manufacturer has patented their shape, because they think it outperforms their competitor's shape (and avoids violating their competitor's patents). Eventually patents expire, such as Square D's QO (queue oh) patent expired, permitting Murray/Siemens to manufacture its QD (queue dee) breakers for QO panels. Still, Siemens is unable to make breakers that fit both Murray and QO panels, because they are still different. They are locked into the old designs because new breakers need to fit old and new panels alike.

So when you use an alien breaker, the clips and nubs don't mate as intended by the two manufacturers, and this is not an accident, it's by design. They are not trying to keep you from using alien breakers, they are (were) trying to keep from being sued for patent infringement. Anyway, you end up with the clips only mating at 2-4 points instead of flat surface contact, and point contact like that is only good for a couple of amps before it starts melting, opening, arcing and burning."

How true or false is it?
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