[RE-wrenches] enphase and AFI circuits

Gary Easton gary at arp-solar.com
Tue Sep 28 07:29:28 PDT 2010


Has anyone had issues with enphase tripping AFI circuits on the panel they
are interconnected with? In this install the interconnection is a line
side tap.
Gary Easton
Appalachian Renewable Power Systems
NABCEP Certified Solar PV
NABCEP Certified Solar Thermal
740-277-8498

> <DIV style="font-family:Arial, sans-serif; font-size:10pt;"><DIV>First, I
> am not talking about NEC requirements for "arc fault" circuit breakers in
> bedrooms!</DIV>
> <DIV> </DIV>
> <DIV>I hope those on the list who are licensed electricians are very
> familiar with the safety issues of an "arc flash" but I have run into many
> pv installers who do not have a clue, and believe as long as the breaker
> they are working on is disconnected there is no danger when working with
> the panel energized.  This is a VERY dangerous problem and it can
> happen on brand new or old electrical switchgear.  An arc flash
> starts with something across the buss bars of a breaker
> panel or from a buss to ground.  What is hard to understand is this
> is not a true short circuit and will NOT trip any circuit breaker. 
> </DIV>
> <DIV> </DIV>
> <DIV>This makes it very dangerous when working on any energized
> panel.  It starts with any small or poor conductor across the phases
> or buss bars.  This could be anything from a fine wire, a dead
> lizard, rust falling off the interior when you slam the door closed,
> filings from drilling a hole in the panel side, or even removing or
> installing a new or old circuit breaker even if it is not connected to any
> load.  This is just enough contact to allow an arc to form, and as
> soon as the arc forms it goes into melt down which produces 35,000 degree
> temperatures and blows plasma of vaporized copper out the front of the
> enclosure.   Having been near one I can tell you the sound is
> like holding a 12 ga. shot gun next to your ear.</DIV>
> <DIV> </DIV>
> <DIV>Starting in 2004 the NEC started requiring arc flash studies and
> labeling on all electrical panels in all non-residential facilities. 
> Most likely if you run into one of these panels there will be a label on
> the door saying "the arch flash safe distance rating of this panel is 6
> feet"  and indicate that arc flash protective clothing must
> used before touching this panel.   Any commercial
> building owner who does not comply with these new regulations
> can face criminal prosecution if somebody gets fried.   The
> safe way to approach any circuit breaker panel is to stand to the hinge
> side of the door as you open it, and not stand directly in front as most
> people do.  This will deflect the high temperature plasma away from
> your face if it happens.</DIV>
> <DIV> </DIV>
> <DIV>Here are several short YouTube videos, one of a security camera
> view of two licensed electricians doing normal maintenance on new
> switchgear.  One guy is standing in front of a new large circuit
> breaker that he is "cranking" into position.  Later analysis
> indicated one of the rear pins was bent, and as he cranked he was
> deforming it sideways towards the ground buss.  This new breaker
> was not connected to any load. Let me say that again, there was no
> load and no current passing through this circuit breaker. </DIV>
> <DIV> </DIV>
> <DIV>Since an arc has resistance, it allows enough amps
> to maintain the arc, but not enough amps to trip the breakers, which
> is why this will continue to burn and not trip anything. Also, this
> may cascade back through multiple sub-panels as their can be enough
> impedance in a long cable between a main and sub panel to hold down
> the amps below the trip rating of the next breaker up the line. 
> </DIV>
> <DIV> </DIV>
> <DIV>Regardless of what you hear, this is not just a high voltage issue,
> and definitely is a concern down to 208 volts AC which puts
> it into the normal range of a residential 120/240 VAC main
> panel.   If you are adding or removing a breaker in an
> existing panel to connect a new inverter, please make sure the panel
> is de-energized and wear approved arc flash gear!</DIV>
> <DIV> </DIV>
> <DIV>Jeff Yago, DTI Solar</DIV>
> <DIV> </DIV>
> <DIV>  <A
> href="http://www.youtube.com/watch?v=m3_ear4k-Jg">http://www.youtube.com/watch?v=m3_ear4k-Jg</A></DIV>
> <DIV> </DIV>
> <DIV> <A
> href="http://www.youtube.com/watch?v=-iClXrd50Z8&feature=related">http://www.youtube.com/watch?v=-iClXrd50Z8&feature=related</A>    </DIV>
> <DIV> </DIV>
> <DIV> <A
> href="http://www.youtube.com/watch?v=AFlBLQjOAJI&feature=related">http://www.youtube.com/watch?v=AFlBLQjOAJI&feature=related</A></DIV>
> <DIV>            
> </DIV><BR> <BR><HR>Netscape.  Just the Net You Need.</DIV>
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