[RE-wrenches] utility EDS signage

[Kent Osterberg]

Phil,

NEC 690.17 says "Where all terminals of the disconnecting means may be 
energized..."  It would take a pretty rare malfunction of a grid 
connected inverter to energize the load terminals of the utility 
disconnect.  But we have some AHJs that require this label on every ac 
disconnect, all the way back to the utility meter, anyway.  The warning 
is appropriate on the dc disconnect of almost all inverters because the 
capacitors in the inverter take a few minutes to bleed off.

To me, the bigger hassle are plaques required by 705.10.  Can anyone 
give me a reasonable explanation for their value in a utility 
interactive system? I can understand if there is a grid backup system - 
emergency personnel may need to know where to turn off the backup power; 
but a grid interactive inverter shuts down when there service is shut 
down.  It seems to me that this plaque is likely to send an emergency 
responder on a wild goose chase.

Kent Osterberg
Blue Mountain Solar

Phil Schneider wrote:
> Wrenches,
> 
> Our utilities require an external AC disconnect between the inverter and the
> point of interconnection, located next to the meter.  In the past, we have
> marked this switch with the language in 690.17 (although no AHJ or utility
> has required it).  Because we generally argue against the necessity of this
> switch, I don't feel it is accurate to say that "terminals on both the line
> AND load sides may be energized in the open position".
> 
> Do other Wrenches post this plaque?  Is there a way that both line AND load
> terminals of this switch could be energized?  (other than an inverter not
> paying attention to its UL listing?)
> 
> Thanks again for your thoughts,
> P.
> 
> Phil Schneider
> Creative Energies
> 
> 
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