[RE-wrenches] NEC 2014 690.12 Rapid Shutdown

[Exeltech]

Brian,

UL1741, Section 64.11 stipulates the discharge time for capacitors at less than five minutes.

Though the context of this Section specifically addresses capacitors that are accessible by some aspect of inverter disassembly, it would also be appropriate to extend its applicability to DC terminals across which capacitors are connected and are otherwise accessible by an external means, such as DC conductors.


Dan Lepinski


--------------------------------------------
On Fri, 1/31/14, Brian Mehalic <brian at solarenergy.org> wrote:

 Subject: Re: [RE-wrenches] NEC 2014 690.12 Rapid Shutdown
 To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
 Date: Friday, January 31, 2014, 1:52 AM
 
 What about the capacitors on the dc side of the inverter?  My assumption has been that this capacitance is the reason behind the 690.17(E) labeling requirement.  Admittedly I don't understand the discharge capabilities of capacitors, but I've measured their voltage and watched it decay when disconnected from a power source (and heard stories about "toss the capacitive-laden ballast to the newbie ha ha...).  

So the question is, say for a of a roof mounted array and a ground-level string inverter, will additional equipment (either in the inverter or external) be required to isolate the PV/dc circuit conductors from the inverter in order to meet 690.12?  


Brian Mehalic 
NABCEP Certified Solar PV Installation Professional™ R031508-59
IREC ISPQ Certified Affiliated Instructor/PV US-0132


PV Curriculum Developer and Instructor
Solar Energy International
http://www.solarenergy.org



On Tue, Jan 21, 2014 at 8:45 PM, Bill Brooks <billbrooks7 at yahoo.com> wrote:

Brian,
 
The requirement is generic. A listed contactor can meet the requirement. A standard is only necessary for products that want to be innovative in meeting the 30V, 240VA. Killing all power is an option with existing listed equipment. NEC 90.4 does not apply.
 
Bill.