[RE-wrenches] 2014 NEC

Wed May 21 18:48:23 PDT 2014

I recently took a code update course with the electrical inspector in Andover MA, and he said that he is only allowing micro-inverter systems in his jurisdiction at the moment. 

SolarEdge and other auxiliary optimizers are not able to certify that they will shut down within 10 seconds. I understand that the manufacturers are working on this, but I'm not sure about their timeframe. Most jurisdictions in MA, I believe, are accepting SolarEdge or Tigo systems, but they don't comply at the moment with the 10 second shut-down provision in 690.12 (2).

The inspector said that he is interpreting 690.12 (1) to say that the means of performing the shutdown should be within 10'/5' of the array, so that means locating the shutdown means on the roof in most cases. The last time I brought this up on the Wrenches list, it was suggested installers could use some kind of relay setup with an accessible activation switch and a relay disconnect. However, 690.12 (5) says: "Equipment that performs the rapid shutdown shall be listed and identified". 690.12 (5) unfortunately doesn't tell us what the equipment should be listed and identified for. It could be listed and identified for the circuit characteristics and shutdown time, or it could be listed and identified for the requirements of 690.12 as a whole function with its own UL specifications. It's possible to find equipment for the former interpretation, but I'm not aware of anything available for the latter (is anyone writing a UL regime for this?). And I think
 that the latter interpretation is reasonable, given the ambiguity in the way the text is written, and what is usually meant by "listed and identified" taken together.

I like micro-inverters for small systems. And I like the SolarEdge model for larger systems with weird layouts, shading issues, or a premium on production. However, central inverters are, depending on the configuration and size of the system, 0.05 $/W to 0.25 $/W less expensive than micro-inverters or DC optimizer systems, and that increase in cost is most likely to come out of the contractor's pocket. I also see this affecting sales for companies producing central inverters as the 2014 code rolls out across the country. If someone has a solution for central inverters under 690.12 when dealing with skeptical AHJs, I'd appreciate hearing more about it.

Regards,
Jeffrey Quackenbush

On Tuesday, May 20, 2014 2:07 PM, Phil Forest <pforest at southmountain.com> wrote:

>
>
>All in all, not longer, glad to say. 
>Strings can have more modules, so there's fewer home runs. Optimizer wires are longer than module wires, they even reach when installing modules in landscape, so fewer jumpers. Be thoughtful when mounting optimizers to rails so it's easy to connect after module is clamped down. Bolts that attach optimizers slide into rails from the end (UniRac SM type rails). You supply your own nuts and bolts. They supply a star washer for bonding optimizer to rail for EG. 
>We mounted optimizers to modules on one job when using UniRac Sunframe. SunFrame is a pain in my neck, optimizers or not. 
>
>Phil Forest
>South Mountain Company
>
>On May 20, 2014, at 1:33 PM, Will White <William.White at rgsenergy.com> wrote:
>
>
>Phil,
> 
>Do you find that the DC optimizer adds to the amount of time on an install?
> 
>Thanks,
>Will
> 
>From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Phil Forest
>Sent: Tuesday, May 20, 2014 1:26 PM
>To: RE-wrenches
>Subject: Re: [RE-wrenches] 2014 NEC
> 
>Will,
>No problems with inspectors for us in MA, regarding rapid shutdown, since we recently switched to using SolarEdge central inverters with optimizer under each module, for roof mounted installs. 
>So far so good. They seem well made and engineered. Tip: you have to enable the arc fault protection when commissioning, ships disabled. 
>Phil Forest
>South Mountain Company
>
>On May 20, 2014, at 10:59 AM, Will White <William.White at rgsenergy.com> wrote:
>Wrenches,
>> 
>>Is anyone else having problems with inspectors and the 2014 NEC?  In Mass we’re having all kinds of issues with inspectors requiring/allowing an array of different things for 690.12 rapid shut down ranging from roof top disconnects, disconnects on the side of a house 20’ up, disconnects in attics, or only disconnects that can be activated on the ground.  It varies between inspectors.
>> 
>>We’re also having problems with one inspector requiring arc fault breakers on Enphase even though there are no UL listed arc fault breakers that can be back fed or he wants us to run the trunk cable in a raceway.  
>> 
>>It’s getting very difficult to install in Mass.
>> 
>>Thanks,
>>Will
>> 
>>Will White
>>Operations Manager - New England 
>>RGS Energy  
>>64 Main St. |Montpelier, VT 05602
>>tel 802.223.7804 |mobile 802.234.3167 |fax 802.223.8980 
>>RGSEnergy.com | william.white at rgsenergy.com   
>> 
>> 
>> 
>> 
>> 
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