My fun for today

[hornadylnl]

Unwiring and rewiring this.

 

[bmwdud]

the hair on the back of my neck just stood up

 

[hornadylnl]

the hair on the back of my neck just stood up

It's 480v fused at 250 amps. I'm guessing the line side of the buss is 600 amps. Throw the switch, put your jacket on, hardhat with shield and electrical gloves on. Not a problem. Biggest switch I've been in so far though.

 

[obijohn]

No worries, just don't touch the shiny parts.

 

[mcolford]

Ok, I will ask. . . .

What the heck is that?????

 

[hornadylnl]

It's what we refer to as a buss plug. It fits on a housing that holds 3 bars. Each bar has about 280 volts, thus 480 volts 3 phase power. We usually have 600-800 amp service running to these busses and put either 30 amp or 60 amp buss plugs on to feed welders and smaller equipment. This 400 amp plug is feeding a 3 phase breaker panel.

Wiring these aren't near as dangerous as removing or inserting the plug into the buss. Think of it as the really old knife switches used 100 years ago. With this plug, you are putting 3 clamps onto 3 separate live bars. If you were to hold a knife switch to where it was just barely making contact, you will probably see some sparks. With 6-800 amp capacity at 480 volts, there's a risk of an arc flash. When removing a plug, you get it unbolted and yank it out quickly. When you install it, you line it up and give it a quick shove.

In an arc flash or blast, the 2 conductors aren't quite mated up and an arc will jump across the two conductors. It can create one hell of an explosion reaching thousands of degrees.

Go to about 1:10 of this vid and you'll see an arc blast.

[ame="http://www.youtube.com/watch?v=W6Im7PLduwc"]http://www.youtube.com/watch?v=W6Im7PLduwc[/ame]

 

[patience0830]

That looked like it left a mark.

wowzi wowow. ouch

 

[hornadylnl]

This is what it will look like up in the ceiling of a factory.

 

[hornadylnl]

According to Wiki, arc flash can reach 35,000 degrees.

Arc flash - Wikipedia, the free encyclopedia

 

[G-Niner]

That's hot!

 

[Mr. Habib]

Looks like fun. How many calorie suit do you need to play in there?

 

[hornadylnl]

Looks like fun. How many calorie suit do you need to play in there?

I'm not sure what the suit rating is. It's like a lab coat.

 

[Mr. Habib]

That's not too bad then. The really heavy ones can get uncomfortably hot, although not as hot a good arc.

 

[Redskinsfan]

Wow, fascinating video. Thanks for posting.

I have never seen anything like that before.

Terry

 

[Mgderf]

Back in the late '70's I was in the Marine Corps. stationed in Beaufort, S.C.
Part of my job as a preventive maintenance tech. included doing routine maintenance checks on all our flight-line gear.

One piece of gear I was charged with maintaining was a portable electrical supply unit.
It was diesel operated, and supplied aircraft on the flight-line with power to start up, or just for maintenance on the tarmac.

The shut-down proceedure for this machine was to turn off the load before turning off the unit power.

I watched a fellow Jar-head ignore this proceedure, much to his detriment. He pulled a 440v power cord from it's socket with the circuit still energizerd. The resulting arc-flash looked a lot like the video above, but much shorter in duration.

The resulting arc threw that poor man about 15' from where he was previously standing and knocked him out cold.

Several of us thought he was dead. 25 minutes later, medics managed to wake him up and hauled him off to the infirmary.

No lasting injuries, but that guy NEVER pulled another "hot cord" out again, and I've never forgot that sight.