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



Matt Correcto mundo -  Jim Lux and I had an interesting debate about thus
point several years ago,  Since you are building one off equipment and it
is considered portable equipment; as long as your using a UL approved cord
set and your upstream over current protective device is coordinated to
protect the cord set (I.e. No intrinsic fire hazard) you'd be compliant.
 But remember one of the global phrases of the NEC under purpose:

"Compliance herewith and proper maintenance results in an installation that
is essentially free of hazard but not necessarily efficient, convenient, or
adequate for good service or future expansion of electrical use."

2005 Illustrated National Electric Code, Purpose 90.1(B), Adequacy

It is up to the "designer" to meet the complete spectrum of system use.
 There are literally thousands of industrial control circuits listed on GE,
Group Schneider/Square D, and Eaton websites that are public domain, free
for use, that show circuits proven to be safe and adequate over millions of
hours.

Designing to an industrial standard is not
cheap, but even using "repurposed"
components will be less likely to have
failures then "Home Depot" or "Radio Shack" parts.  And yes I use 600v
contactors on 250v because I want the circuit to be
robust and open when it is commanded to do so.  In fact I've never (being
bold now to date) had an industrially rated component fail
catastrophically on any systems where I used them, even when the contacts
were overloaded beyond OEM spec ratings.  But it is your problem I f
something does fail.

On Thursday, August 21, 2014, mddeming--- via Tesla <tesla@xxxxxxxxxx>
wrote:

>
> Hi Jim,
>
>
> 1. Any mandatory code for hobbyists would be de facto unenforceable.
>
>
> 2. Murphy was an optimist. ;^))
>
> Matt D.
>
>
>
>
> -----Original Message-----
> From: Jim Mora <wavetuner@xxxxxxxxx <javascript:;>>
> To: 'Tesla Coil Mailing List' <tesla@xxxxxxxxxx <javascript:;>>
> Sent: Thu, Aug 21, 2014 7:53 am
> Subject: Re: [TCML] NIST High Voltage Laboratory Testing / Safety Reference
>
>
> 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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