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Woops!
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subego
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Join Date: Jun 2001
Location: Chicago, Bang! Bang!
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Jan 31, 2018, 03:53 PM
 
Surprisingly, no death or injury.



(More woops to come)
     
Chongo
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Jan 31, 2018, 04:15 PM
 
More oops 11-8 videos on youtube
"The blood of the martyrs is the seed of the church" Saint Tertullian, 197 AD
     
subego  (op)
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Jan 31, 2018, 04:25 PM
 
A classic!

There’s one which usually follows it around about an impossible to see speed bump. I try and dig it up.
     
subego  (op)
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Jan 31, 2018, 04:28 PM
 


     
subego  (op)
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Feb 2, 2018, 03:13 PM
 


Analysis is they accidentally hit the (pedal activated) emergency brake.
     
subego  (op)
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Feb 2, 2018, 03:50 PM
 
A woops to be



Am I doing the math right? That looks about 13 million watts.
     
reader50
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Feb 2, 2018, 06:36 PM
 
Max amps would be a dead short, at 0 ohms load. Their numbers suggest a line resistance of .02 ohm.

If you assume 1 ohm for the person in circuit (wet hands and standing in water) with .02 ohm line resistance, you'd get maybe 460 amps at 470 volts. Amps would go up rapidly as your skin resistance failed further, while voltage would drop more slowly.

The label is misused. 480 VAC is medium voltage according to the NEC, and personal protective equipment (PPE) absolutely works with 480. Electrical tape would be enough. Dry gloves, rubber gloves, even bare hands if you're wearing dry shoes (and only touch one leg) would work. I'd expect that label at several KVAC or higher.
     
subego  (op)
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Feb 2, 2018, 10:41 PM
 
IIUC, the warning is because of the heat an arc fault would release. Second degree burns at 30 feet.

I gather there actually is PPE which can handle what would be encountered at working range, but it won’t handle the accompanying getting blown across the room.
     
subego  (op)
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Feb 3, 2018, 02:12 AM
 
     
ghporter
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Feb 4, 2018, 07:05 PM
 
Originally Posted by reader50 View Post
Max amps would be a dead short, at 0 ohms load. Their numbers suggest a line resistance of .02 ohm.

If you assume 1 ohm for the person in circuit (wet hands and standing in water) with .02 ohm line resistance, you'd get maybe 460 amps at 470 volts. Amps would go up rapidly as your skin resistance failed further, while voltage would drop more slowly.

The label is misused. 480 VAC is medium voltage according to the NEC, and personal protective equipment (PPE) absolutely works with 480. Electrical tape would be enough. Dry gloves, rubber gloves, even bare hands if you're wearing dry shoes (and only touch one leg) would work. I'd expect that label at several KVAC or higher.
In my experience the use of signage around dangerous electrical systems tends to be as (excuse the pun) inflammatory as possible. It either gets your attention or it's useless. Having felt what 1200 watts going through your finger tip is like (not fun at all!) from an accidental contact inside something called a "cold compartment" - without signage - I get the point.

Glenn -----OTR/L, MOT, Tx
     
subego  (op)
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Feb 4, 2018, 09:33 PM
 
In a similar vein, I have high explosives warning labels I put on boxes of spare bulbs to incline people to be gentle.
     
subego  (op)
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Feb 9, 2018, 01:08 PM
 


Subaru FTW.
     
andi*pandi
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Feb 9, 2018, 01:39 PM
 
just like mario kart.
     
subego  (op)
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Feb 12, 2018, 02:11 AM
 
Double woops.

     
   
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