Check Before You Drill

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Dull drill bit drilling a EGC lug in a transformer, I once drilled through the skin between my thumb and fore-finger.


Gotta be careful.
 
electricmanscott said:
How did the camera just happen to be there at that moment? :-?
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Thats probably about 10,000 amps unfused off the xformer get yourself a snickers cause its gonna be a while.
As for drilling outwards through cedar shakes he should have been beaten thoroughly before he was electrocuted and burned in the ensuing fire.
The cable man did this on my house with beveled cedar tounge and grove planking. He beat feet when he heard me on the other end of the phone when my wife called me to tell me he drilled a hole out the side of the livingroom wall.
 
quogueelectric said:
Thats probably about 10,000 amps unfused off the xformer . . .
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If it is a normal subdivision with no electric heat homes, it is a 25 kVA transformer, will not put out more than 7700 amperes, and will drop most of it going through the secondary and service drop. However, from the looks of the arc, you are correct, it is probably coming from a 50 or 75 kVA.

The transformer is probably fused to protect the line and will not blow until the fault is pretty solid at the bushings or there is an internal fault. We use a 15 T fuse on a 25 kVA transformer at 7.62 kV. The T rated fuse will carry 150% indefinitely. Do the math and you will see that the transformer is not protected. :smile:
 
crazyboy said:
It's probably going to burn until it's de-energized.
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Protected conductors will generally arc for a short time while the protection device decides to open.

Unprotected conductors can arc and spark for quite a while before enough material vaporizes to permanentyly quench the arc. The arc can strike, go out, restrike, go out, restrike many times. In this case, someone with the wherewithall to grab a camera could easily take such a photo.
 
This is what happened when the home owner decided to show where the placement of the outside lighting was going to go. The markings on the inside looked great BUT. The cordless drill was fine. At first the cable just gave off a small bit of smoke. Then whamo it lit up. I went up and cut the taps the sound was one you will never forget.
 
As far as the camera being there, This took quite a while to reach this point. The home owner took the shot. But we won't show his insurance co.. There was only about a dozen shingle that had to be replaced.The sheathing was fine didn't even burn the tyvek.
 
knot stable said:
This is what happened when the home owner decided to show where the placement of the outside lighting was going to go. The markings on the inside looked great BUT. The cordless drill was fine. At first the cable just gave off a small bit of smoke. Then whamo it lit up. I went up and cut the taps the sound was one you will never forget.
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Holy moses, are you out of your mind!
 
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