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Re: [TCML] NIST High Voltage Laboratory Testing / Safety Reference


Actually is some regards it is "enforceable"
via National Electric Code.  My litmus test
1.  Does it look "right" compared to HV high
power industrial equipment I have experience?
2.  Is there a one,  two, or three level failure chain
that could expose a bystander or unqualified
person to lethal voltages?
3. Are the clearances adequate based on 2X nominal maximum
4.  Is the over current protective devices adequate to interrupting
worst case currents in the event of a fault and your CB fails to
There are many other considerations, but redundant circuits,
over current protection (and backup in case one level failure
occurs), and adequate clearances are carefully considered.
As an industrial reference, the Federal Energy Regulatory
Commission (FERC) required TWO independent, parallel
generator protection relays on power producers, and
 furthermore they must be from different manufacturers
with different algorithms.  Both have to agree to allow
unit to run, but EITHER can independently trip the
lockout 86G relay to the grid.

But absolutely top on list is proper grounding and bonding
using UL listed components operated within their stated
capacities.  Bad, improper, or incomplete grounding has
killed many folks and blown a he$$uva lot  of equipment

Bottom line:  You should never be cavalier working around
power. And especially high voltage power.  There is no
second chance.

On Thursday, August 21, 2014, Jim Mora <wavetuner@xxxxxxxxx> wrote:

> Hi Dave,
> Thank you. This is excellent and really common sense information. The
> question now arises when this will become mandatory code for the HV
> hobbyist
> or is it already?
> My new Murphy law addition after breaking my leg with a transformer: "If an
> accident is possible, it eventually will happen at the worst possible
> moment".
> Jim Mora
> -----Original Message-----
> From: Tesla [mailto:tesla-bounces@xxxxxxxxxx <javascript:;>] On Behalf Of
> David Sharpe
> Sent: Wednesday, August 20, 2014 4:10 AM
> To: Tesla Coil Mail List
> Subject: [TCML] NIST High Voltage Laboratory Testing / Safety Reference
> Truly excellent reference for use when designing
> medium or high voltage equipment or performing HV lab work,
> from NIST.  This document was referenced in a recent
>  EDN e-blog.  The great thing about this document is it
> is succinct, brief (9 pages), specific, and to the point.
> http://www.nist.gov/el/isd/mmc/upload/high_voltage_rules_revised.pdf
> <One recommendation is the requirement of having "2"
>  separate operations to turn on high voltage; this requires
> at a minimum a Main Disconnect (Lockable Safety Switch)
> and a start-stop push-button station with seal in contactor.
> This requirement supports my contention you should never
> "instant on" high voltage equipment.  YMMV, but I've seen
> catastrophic, spectacular failures doing this.
> <snip>
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Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA

Sharpe's Axiom of Murphy's Law
"Physics trumps opinion!"
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