switchboard explosion

[Pierre C Belarge]

I have not seen anyone mention this, but the OP mentioned the OCPDs exploded and then goes on to ask how is this possible.

It is highly possible that the OCPDs were not proper rated in regards to AIR rating and may have helped to contribute to the condition escalating.

 

[Cold Fusion]

I have not seen anyone mention this, but the OP mentioned the OCPDs exploded and then goes on to ask how is this possible.

It is highly possible that the OCPDs were not proper rated in regards to AIR rating and may have helped to contribute to the condition escalating.

I did think of that - aluded to it in post 6. But I couldn't figure how a bus fault would rotate through the load side of each of the feeders. That's why I was wondering about a primary-secondary xfm fault, sending the feeder cbs way over-voltage. That piece still puzzles me.

cf

 

[quogueelectric]

I did think of that - aluded to it in post 6. But I couldn't figure how a bus fault would rotate through the load side of each of the feeders. That's why I was wondering about a primary-secondary xfm fault, sending the feeder cbs way over-voltage. That piece still puzzles me.

cf

Not me I have been in and around a few plasma clouds/ Arc flash the air surrounding all of the equipment becomes conductive due to copper plasma and ionized air. There are no rules once this flashes over. It is like someone throws a bucket full of chain across all phases and ground simultaneously. Badness is all around you. Run for your life!

 

[Cold Fusion]

There are no rules once this flashes over. It is like someone throws a bucket full of chain across all phases and ground simultaneously. Badness is all around you. Run for your life!

I'd agree with most of that - especially the "Run for your life" part. But the badness still follows the laws of God and physics.

Which leads me to my next thought.

I have been upclose and personal in one of these explosions.
The initial arcfault welded the breaker in the closed position 600 amp 480 3ph directly off a padmount 13k/480 xformer.
I tried to time the explosions and ran back in the room to try to open the breaker with a 2x4 but it was already welded closed.

Your posts have always struck me as well thought out and showing good reasoning. So, what were you thinking when you ran toward the fault

cf

 

[boboelectric]

I have seen that happen a few times when 480 switchgear starts to arc fault,phase to phase, and vaporize the al bus bar.The main breaker doesn't see a problem. What a nightmare to repair.