I have done a lot of work at the Robert Moses Niagara Power Project (at
Niagara Falls). One time a contractor was working on grouting concrete on
the top of an enclosure above a 169MW transformer. There was a large hole in
the middle of the roof for cooling, etc. Said contractor dragged his
extension cord across the roof and it fell into the hole, directly across a
115KV bus.

Talk about sparks! (and an amazing bang)

Miraculously no one was hurt.

Bob Ammerman
RAm Systgems

----- Original Message -----
From: "Welch, Ken" <Ken.Welch@SPIRENTCOM.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, May 29, 2002 10:23 PM
Subject: Re: [EE]:formula/link for current capacity of wire (AC)


> there was a telco central office in north Texas (too many years --40+) --
> typical painted cinder block walls
>
> they were doing some installation work and a open end wrench fell (from
> above) onto the live 48 VDC bus bars -- vaporized the wrench and some bus
> bar...
>
> fortunately, no one was hurt, and the circuit breakers/fuses prevented a
> major meltdown but you could go up to any spot on the wall with an
ohmmeter
> probes and measure about 20 ohms... first central office with a plated
walls
> !
>
> construction practice since then was covered raceway below AND above bus
> bars...
>
> -----Original Message-----
> From: Russell McMahon [mailto:apptech@PARADISE.NET.NZ]
> Sent: Wednesday, May 29, 2002 1:42 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]:formula/link for current capacity of wire (AC)
>
>
> > So use two railroad track pieces, each 20ft long, as conductors. They
are
> > too heavy to move and the current capacity should be enough. Cheap too.
> > Imho don't worry too much about 800A in a single loop moving heavy
> > conductors. If you'd use say 100 turns at that current, it would begin
to
> > be interesting.
>
> NZ Telecom (then NZPO) use large copper bus bars to carry exchange 50
volts.
> These are run parallel with spacers to keep them apart. During maintenance
> some spacers were removed and, contrary to official practice, the current
> was restored. The bus bars attracted each other enough to touch and
started
> a self sustaining arc. Now THAT would have been a site to see. 50 VDC with
a
> battery good for maybe 10,000 Amps and large copper feed. Nobody hurt.
> Didn't hear what happened to the techs afterwards.
>
>
>         Russell McMahon
>
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