[RE-wrenches] Article 690, or The Haves Vs. Have Nots

Drake drake.chamberlin at redwoodalliance.org
Wed Apr 30 08:21:58 PDT 2014


Inverter ground fault fuses certainly do 
blow.  What is causing your string fuses to go?


At 10:17 AM 4/30/2014, you wrote:
>"​
>An AC breaker is far more likely to trip than a DC string fuse"
>
>I completely disagree. We have never, not once, 
>had to reset a tripped inverter output circuit 
>AC breaker that I know of, but have replaced 
>many dozens of DC string fuses and GFCI fuses in 
>inverters, most of the time for undiagnosed 
>failures.​ There is a reason we keep a good 
>supply of 1A, 15A, and 20A Littlefuses in a drawer here.
>
>Jason Szumlanski
>
>
>Â
>
>
>On Wed, Apr 30, 2014 at 9:56 AM, Drake 
><<mailto:drake.chamberlin at redwoodalliance.org>drake.chamberlin at redwoodalliance.org> 
>wrote:
>There are good reasons to want to put AC 
>combiners under modules, but some reasons not to want to.
>​​
>An AC breaker is far more likely to trip than a 
>DC string fuse, due to the surge availability. 
>As a PV system is designed to last a minimum of 
>25 years, the installer might not be the one to 
>sort out problems decades down the line.
>
>A strategy I prefer would be to use a SolaDeck 
>as a junction box. Run small wires to a convenient AC combiner location.
>
>
>At 12:43 PM 4/29/2014, you wrote:
>>Dave
>>
>>I agree, in the case of microinverters, you 
>>already have a main PV System disconnect at the 
>>Load Panel to shut down the system that is 
>>readily accesible.  I would consider the 
>>disconnect on the roof as a supplemental 
>>disconnect for the purposes of maintenance by 
>>authorized personal that only needs to be accessible.Â
>>
>>Bill
>>
>>
>>On Tue, Apr 29, 2014 at 8:44 AM, Dave Click 
>><<mailto:daveclick at fsec.ucf.edu>daveclick at fsec.ucf.edu > wrote:
>>I think 240.24(A)(4) allows the installation of 
>>the inverter OCPDs in the SolaDeck hidden under a module.
>>240.24 Location in or on Premises.
>>(A) Accessibility. Overcurrent devices shall be 
>>readily accessible and shall be installed so 
>>that the center of the grip of the operating 
>>handle of the switch or circuit breaker, when 
>>in its highest position, is not more than 2.0 m 
>>(6 ft 7 in.) above the floor or working 
>>platform, unless one of the following applies:
>>...
>>(4) For overcurrent devices adjacent to 
>>utilization equipment that they supply, access 
>>shall be permitted to be by portable means.
>>
>>And if panelboards / fused safety switches are 
>>allowed to have screwed-down covers over the 
>>OCPDs, I'd think that installing a removable 
>>module over these OCPDs would meet NEC. I guess 
>>an AHJ could argue that this requires TWO 
>>covers be removed, unlike a panelboard or a switch.
>>DKC
>>
>>On 2014/4/29, 11:15, Jason Szumlanski wrote:
>>>690.9(D) is not applicable to the original 
>>>discussion because we were talking about an 
>>>Inverter output circuit, not a PV Source or Output circuit.
>>>690.34 may apply if you call a SolaDeck with 
>>>breakers a junction box, but I can see that 
>>>being a stretch in the mind of many.
>>>My and Ray's question about the screws on the 
>>>SolaDeck cover itself requiring a tool to 
>>>render it accessible is still an issue if the 
>>>breakers themselves need to be "readily 
>>>accessible," but that would also apply to a 
>>>Midnite MNPV, which also has a cover with a screw.
>>>
>>>Jason Szumlanski
>>>
>>>On 4/28/2014 5:57 PM, Bill Brooks wrote:
>>>>Read 690.9(D) and 690.34. Not sure where this 
>>>>“hysteria­run for the border” sentiment is coming from.
>>>>
>>>>Â
>>>>690.9(D) Photovoltaic Source and Output Circuits. Listed PV
>>>>overcurrent devices shall be required to provide overcurrent
>>>>protection in PV source and output circuits. The overcurrent
>>>>devices shall be accessible but shall not be required to
>>>>be readily accessible.
>>>>Â
>>>>690.34 Access to Boxes. Junction, pull, and outlet boxes
>>>>located behind modules or panels shall be so installed that
>>>>the wiring contained in them can be rendered accessible
>>>>directly or by displacement of a module(s) or panel(s) secured
>>>>by removable fasteners and connected by a flexible
>>>>wiring system.
>>>>Â
>>>>This is not a change. Please help me understand the concern.
>>>>Â
>>>>Bill Brooks.
>>>>Â
>>>>Â
>>>>From: 
>>>><mailto:re-wrenches-bounces at lists.re-wrenches.org>re-wrenches-bounces at lists.re-wrenches.org 
>>>>[ mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Ray Walters
>>>>Sent: Monday, April 28, 2014 2:23 PM
>>>>To: RE-wrenches
>>>>Subject: Re: [RE-wrenches] (no subject)
>>>>Â
>>>>Interesting so does "require a tool" include 
>>>>taking a screw off the cover plate of the combiner box, too?
>>>>What a game changer.  I'm going to Mexico 
>>>>for my next project; I'll actually enjoy even 
>>>>more being the sole AHJ on the project.Â
>>>>
>>>>
>>>>
>>>>R.Ray
>>>>
>>>>Walters
>>>>
>>>>CTO, Solarray,
>>>>
>>>>Inc
>>>>
>>>>Nabcep Certified PV Installer,
>>>>
>>>>
>>>>Licensed Master
>>>>
>>>>Electrician
>>>>
>>>>Solar Design
>>>>
>>>>Engineer
>>>>
>>>><tel:303%20505-8760>303
>>>>
>>>>505-8760
>>>>On 4/28/2014 2:52 PM, Michael Morningstar wrote:
>>>>
>>>>Readily accessible is now defined in the 2014 
>>>>NEC. Installing OCPD’s underneath a module 
>>>>is a major faux paux, and I can’t imagine 
>>>>any AHJ thinking otherwise. Having to remove 
>>>>a module in order to reset a breaker, what a drag.
>>>>Â
>>>>"Capable of being reached quickly for 
>>>>operation, renewal or inspection without 
>>>>requiring those concerned to use a tool, to 
>>>>climb over, remove obstacle or other.”
>>>>Â
>>>>Michael
>>>>Â
>>>>Â
>>>>Â
>>>>
>>>>
>>>>On Apr 28, 2014, at 10:29 AM, William Miller 
>>>><<mailto:william at millersolar.com>william at millersolar.com > wrote:
>>>>
>>>>
>>>>
>>>>You call it a solar panel, I call it a glass j-box cover plate.
>>>>William
>>>>Miller Solar
>>>>
>>>>
>>>>On Apr 28, 2014, at 9:21 AM, Jason Szumlanski 
>>>><<mailto:jason at fafcosolar.com>jason at fafcosolar.com> wrote:
>>>>If that is the interpretation,
>>>>I don't see how the breakers are "readily accessible" in a SolaDeck
>>>>mounted anywhere, regardless of whether it is under a module. It
>>>>requires removal of four screws (using a tool) to access the breakers
>>>>inside the enclosure. It's all up to the AHJ. It has not been an issue
>>>>locally here. I can see how other jurisdictions may not
>>>>concur.
>
>
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