Burning Wirenut

[romex jockey]

http://c-joule-effect-inc.com/electrical_fires.html

~RJ~

 

[Ponchik]

it is nice. I can show to others what loose connection will cause.

 

[K8MHZ]

Are those MC connectors used on NMS?

Not that it makes a difference......

 

[mike7330]

This one of many reasons you need to put cover plates, ko seals, 1/8 min. gap around outlet boxes and 1/4 inch max set back on boxes.......... and I know that many of us can add to this and cite code.

 

[Sierrasparky]

Why is the AFCI not tripping maybe the version he is using does not detect a series fault. Seems odd to me.

 

[mjf]

Are those MC connectors used on NMS?

Not that it makes a difference......

No, those are Combo connectors.....for MC or NM.

 

[Ponchik]

This one of many reasons you need to put cover plates, ko seals, 1/8 min. gap around outlet boxes and 1/4 inch max set back on boxes.......... and I know that many of us can add to this and cite code.

I am sure there are a lot more violations but the OP has not posted for us to call out violations of NEC.

He is showing the dangers of loose connections which is a habit of a unqualified person.

 

[George Stolz]

I have a technology that already prevents the fires this device protects against:

 

[mike7330]

I am sure there are a lot more violations but the OP has not posted for us to call out violations of NEC.

He is showing the dangers of loose connections which is a habit of a unqualified person.

You are missing my point. No matter how good we are at our jobs, connections do come loose. And if your boxes ....ect are sealed properly it would reduce the spread of fire.

 

[Ponchik]

You are missing my point. No matter how good we are at our jobs, connections do come loose. And if your boxes ....ect are sealed properly it would reduce the spread of fire.

I need to disagree with you. Once the connections are done correct using the correct material and are in the correct environment then they shouldn't come apart.

 

[mike7330]

277 volt lighting circuit. still on. and the lights working.

 

[Sierrasparky]

That looks like the box got wet and caused the failure

 

[Ponchik]

277 volt lighting circuit. still on. and the lights working.

If the connection is done correctly, it shouldn't fail unless it is due to another factor (ie. loose connection, incorrect material, by unqualified person, foreign object (dust, water, fumes...) or any other thing...) Otherwise a good connection should not fail.

 

[romex jockey]

Folks

please note this series event was not mitigated by either gfci or afci

~RJ~

 

[mike7330]

That looks like the box got wet and caused the failure

No box installed on I beam. there was no signs of water damage

 

[don_resqcapt19]

Why is the AFCI not tripping maybe the version he is using does not detect a series fault. Seems odd to me.

I have not seen anything that would lead me to believe that an AFCI, even of the combination type, will detect and clear a high resistance connection. There are two issues. First is it an arcing connection. A high resistance connection can produce enough heat to cause a lot of damage without being an arcing connection. Second you can produce a lot of heat in a small area with currents less than 5 amps. Even if it is a series arc, the AFCI does not look at the arc signature unless the current exceeds 5 amps.

It is my opinion that this type of problem is the main reason why most brands of AFCIs have GFP protection. At some point, hopefully before the building is on fire, this type of fault will become a ground fault and the GFP part of the AFCI will clear the circuit. It seems to me that the newer GE AFCIs, without ground fault protection lose a lot of their ability to protect in cases like this.

 

[ICC]

If the connection is done correctly, it shouldn't fail unless it is due to another factor (ie. loose connection, incorrect material, by unqualified person, foreign object (dust, water, fumes...) or any other thing...) Otherwise a good connection should not fail.

It is true in theory , but if I well recall the resistance of a connection is the sum of a number of sub-resistance linked and depending from each other. For instance : Copper naturally oxydize as soon as placed in open air. Copper oxydation at contact point generate a resistance and a small heating up at the beginning. Heat produced will increase other sub-resistance and favor even more oxyde creation and more heat. This is one potential cause of glowing connections.

 

[Sierrasparky]

No box installed on I beam. there was no signs of water damage

Ok so that brown colored stuff in the box they call rust just got there by majic. Then there is the oxidation on the outside of the box. Majic again!
This box was subject to some moisture and may have degraded the splice.
I am sitting at my desk so I cannot be sure.

 

[mike7330]

Ok so that brown colored stuff in the box they call rust just got there by majic. Then there is the oxidation on the outside of the box. Majic again!
This box was subject to some moisture and may have degraded the splice.
I am sitting at my desk so I cannot be sure.

Sierraspark, Here is the same box on the 2nd floor of 9 story building no plumbing in this area. Don't know why the interior of box is rusted.
could be from the heat and fire or the hack that installed this box used a rusted one. Your guess is as good as mine. thanks

 

[Sierrasparky]

could one of the cables wicked water into the box.