Isolation is a must!!!!!!!! or this happens

[Darkwood]

Watch this at about 1.08 ..... my first thought and dont ask me why was where was the emergency lighting???




LiveLeak.com - arc flash electrocution

 

[lofty84]

Jesus poor guy, that's all you wanna see as a sparky

 

[GJH]

Was racking in a switch which was probably still in "earth"?

 

[Engineer54]

The earthing switch, earths out the cores of the connected cable, not the breaker!! You also can't rack in a breaker that is in the ON position. The trick with racking in or out breakers/fuse switches is speed!! you don't stop until the breaker is fully engaged into the connection spouts.

 

[lofty84]

Racking/rack ?

 

[Engineer54]

The most common cause of ''Arch Flash'' is containments!! Which can range from higher than normal humidity being present, heavy dust build up on the spouts, tracking carbon build-up around the spouts from corona effects, to an old cleaning rag being left un-noticed during maintenance, to tools etc...

 

[Engineer54]

Racking/rack ?

Rack/Racking = Winding in (or out) the breaker to it's engaged operation position or to it's disengaged position!!

 

[lofty84]

Would love to know what your talking about but it's a bit above my head. I always thought the earth cable was so fault current has somewhere to run b4 travelling back through earth to the transformer

 

[Knobhead]

Watching it they seemed to take breaks in the racking operation where, as E54 said speed is essential.
Ionised air can build up in the spout as the contacts approach each other causing flash over.

 

[Top Cat]

I have seen this sort of thing first hand. I was about to fit power factor correction equipment in the same sort place.

Because of this another company were going to carry out maintenance work. An engineer told us all panels were dead and the maintenance people went in first i think he dropped a spanner across the bus bars.

An explosion like the one seen happened the guy was blinded (do not know if he got his sight back or just ark eye) had to drag him out.

6" x 1" bus bars were twisted like they were made of toffee and still alive.

Turned out the "engineer" did not realize that two supplies were taken into building and he had only isolated 1!!!

I had given up the smokes for 6 months until then. Started an hour later.

Most frightening thing i have ever seen.

 

[Engineer54]

Watching it they seemed to take breaks in the racking operation where, as E54 said speed is essential.
Ionised air can build up in the spout as the contacts approach each other causing flash over.

That's exactly what i noticed too!! Those breaker connectors must have been hissing like mad entering the spouts, but those workmen wouldn't have heard that, as they had the ear muffs on ...lol!!

 

[Darkwood]

Well whatever the cause it made certain spherical muscles tighten up on my body :46:.......

 

[Knobhead]

I have seen this sort of thing first hand. I was about to fit power factor correction equipment in the same sort place.

Because of this another company were going to carry out maintenance work. An engineer told us all panels were dead and the maintenance people went in first i think he dropped a spanner across the bus bars.

An explosion like the one seen happened the guy was blinded (do not know if he got his sight back or just ark eye) had to drag him out.

6" x 1" bus bars were twisted like they were made of toffee and still alive.

Turned out the "engineer" did not realize that two supplies were taken into building and he had only isolated 1!!!

I had given up the smokes for 6 months until then. Started an hour later.

Most frightening thing i have ever seen.

That shows the importance of a switching schedule. Had a schedule been made out and verified by another authorised person, alarm bell should have been ringing.

Not long after I came out of my time we had a 11KV flash over in an unmanned sub. I was chiselling bits of porcelain spout insulators out of the brick work, had anyone been in there if the ark flash didn’t get them the shrapnel would have.

 

[Knobhead]

That's exactly what i noticed too!! Those breaker connectors must have been hissing like mad entering the spouts, but those workmen wouldn't have heard that, as they had the ear muffs on ...lol!!

The moment I hear the hissing I go in to 2[SUP]nd[/SUP] gear winding.

 

[Midwest]

Good job they were wearing the correct PPE! Do we know what happened to them?