Our company produces Laboratory Equipment. We design to the IEC/EN/UL 61010-1 
series of standards and the NFPA 70 NEC.

Some of our instruments can be quite large; slightly bigger than an upright 
piano. They typically are powered by 230VAC, 20A to 50A branch circuits. It is 
typical that our instruments are installed near or in a heavy industrial 
environment even though they are not considered Industrial Machines. They are 
sometimes mistaken as Industrial Machines.

Recently, we have had customers ask the following questions about our 
instruments:

*       Proof that the electrical system complies to NFPA 79.
*       Are the electrical enclosures marked for arc flash hazard per NFPA 79?
*       What is the Short Circuit Current Rating (SCCR) of our instruments?


Typically we simply reply that our instruments are not Industrial Machines and 
that is that. However, if there is information we can provide that would be 
helpful, we would like to do so.

I can see where our customer may wish to power our instrument from a circuit 
that is capable of producing very high short circuit current (SCC). If this 
exceeds the 5kA rating of our internal Supplementary Protection Device, then 
our customer would have to supply a Brach Circuit Breaker that can handle the 
SCC.

High SCC can also cause a concern for Arc Flash. I do not know the requirements 
of NFPA 79 and how it affects Arc Flash. For instance,  since our chassis meets 
the mechanical requirements called out in IEC 61010-1, is it likely that our 
chasses will contain the arc flash hazards?

Is there any part of NFPA 79 that could apply to our instruments; to the 
mechanical or electrical system?

Has something changed recently which would explain why we are now receiving 
these type of questions?

Thanks for any input or advice.

The Other Brian




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