Re: NFPA 70E Training outcomes (Ref: Safety Training...)

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Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

Who was the training offered by?  NFPA?

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From: "Tesla list" <tesla-at-pupman-dot-com>
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Sent: Thursday, August 26, 2004 6:35 AM
Subject: NFPA 70E Training outcomes (Ref: Safety Training...)


 > Original poster: Sparktron01-at-comcast-dot-net
 >
 >
 > List
 >
 > I attended this training several weeks ago (2 days).  There were many
 > videos of severe injuries and fatalities arising from "Arc Flash/
 > Electrical Explosions", and several videos of staged electrical explosions
 > (up to 15kV -at- 5kA) that were frightening to say the least (see Bert
 > Hickman's video of the substation catastrophic KABOOM to have a similar
 > reality check).  The interesting take homes and statistics from this
 > training are:
 >
 > 1.  80% of nationwide electrical fatalities involved qualified electrical
 > personnel (i.e. they had multiple years experience in electrical trade).
 >
 > 2.  Many fatalities involved "gettting comfortable" in your job, and
 > eventually leads to shortcuts being taken (complacency).  On HV gear this
 > is an invitation for disaster.
 >
 > 3.  HV and high power LV equipment can have equipment failure, and if you
 > are near it when it lets go, all bets are off unless you have PPE
 > on.  Water expands from liquid to vapor 1700 times it's liquid
 > volume.  Copper vapor / plasma expands 64,000 times (!!!!!) its original
 > solid volume.  Under a high energy fault condition, this will result in a
 > violent thermal explosion with molten debris, and electrical plasma being
 > ejected at high velocity, with a time duration of 0.5 sec or less.  Impact
 > energies can be suffciently high to shear 3/8" steel bolts.  Imagine
 > several thermite grenades and sticks of dynamite going off in confined
 > quarters simultaneously...
 >
 > 4.  Many folks have died by bad meters, meter leads, or making an
 > ASSumption that the power was turned off and no back feed path existed.
If
 > a DVM is not rated for class III (CB panelboard) service, and a high
energy
 > HV transient causes an arc over internal to meter; can result in a meter
 > explosion.  The moral of the story is DO NOT risk your life using a $3.00
 > Harbor Freight (or similar) DVM's, use an industrially rated meter if
 > working on high power/energy circuits that may be live.  Also if you have
 > to replace the meter fuse, replace it with the EXACT replacement, they are
 > usually designed with higher then normal interrupting and voltage clearing
 > rating (AFAIK Fluke uses 17kA / 1kV ceramic cartridge fuse in ammeter
 > circuit as an example).
 >
 > 5.  Circuit breakers should be mechanically exercised ONCE A YEAR.  This
 > was a revelation to me, but with our TC's of various flavors pounding our
 > house panels, please take heed.  The CB mechanism can be uncalibrated by
 > extended time running at 90-95% of breaker ampacity by internal
 > heating.  This may preclude the breaker from operating at all.  If you
 > operate the breaker and it does not "feel" right, or sounds "mushy" when
 > the contacts open and close; REPLACE THE CB.  It is cheaper then replacing
 > your house!
 >
 > 6.  Fuses are a much more reliable high energy interrupting means then
 > CB's.  They are commercially available with interrupting ratings to 300kA,
 > and low-peak fuses will clear a high energy fault in less then 1/4 cycle
 > 60Hz (4 millisecs).  Low peak fuses also dramatically limit arc/flash
exposure.
 >
 > 7.  Use GFI's, they are lifesavers.
 >
 > 8.  Wear cotton clothing rather then synthetics when working around HV or
 > high energy circuits, the synthetics when exposed to arc/flash can melt
 > into the skin and cause severe 2nd and 3rd degree burns.
 >
 > 9.  Avoid working on HV circuits alone, use the "buddy" system.
 >
 > Be safe out there...
 >
 > Regards
 >
 > Dave Sharpe TCBOR/HEAS, Chesterfield, VA. USA
 >
 >
 >
 >