[RE-wrenches] Rapid Shut Down and the 10 Second Rule Questions

Tue Feb 3 12:10:06 PST 2015

Thanks David,

This is very helpful.

Mark Frye

On 2/3/2015 12:04 PM, David Brearley wrote:
> Mark,
>
> Bill Brooks’ rapid shutdown article for SolarPro does a nice job 
> walking through the individual subsections of 690.12.
>
> He also addresses initiation device (type and location), which is not 
> covered in the NEC. Here is the relevant text:
>
> *What about the rapid-shutdown initiator?*/ NEC/ 690.12 does not 
> specify where you should locate the initiating device or what type of 
> device you must install. This lack of detail is intended to provide 
> system integrators and AHJs with the flexibility to adapt 
> rapid-shutdown solutions to the complexities of the built environment. 
> While the best location for a rapid-shutdown device and the required 
> label is typically at or near the service equipment, the fire service 
> may have preplanned emergency response tactics for some large 
> commercial or industrial buildings that favor a different location.
>
> One of the simplest ways to initiate rapid shutdown is to set it up to 
> occur automatically upon loss of ac power. This is why /NEC 2014 /does 
> not require a specific type of rapid-shutdown initiation device. If 
> you install a roof-mounted residential microinverter system or a 
> commercial PV system using roof-mounted string inverters located 
> within 10 feet of the array, you do not need any special equipment to 
> initiate rapid shutdown; you can accomplish this function simply by 
> interrupting utility-supplied power to the inverters. Some companies 
> have developed various rapid-shutdown switches, and claim that rapid 
> shutdown requires these extra switches. However, you have to install 
> an extra rapid-shutdown switch only when you need to turn the array 
> off by some means other than loss of utility power, as with 
> battery-backup systems or inverters equipped with a daytime 
> backup-power outlet.
>
> /NEC /690.12 does not specify how many buttons, switches or movements 
> of the hand are allowed to complete rapid shutdown. Ideally, the 
> process should only require one action. As written today, however, the 
> language in 690.12 provides system integrators and AHJs with the 
> flexibility to consider alternatives. Note that if the system design 
> requires more than one action to initiate rapid shutdown, the 
> 10-second time limit still applies. Therefore, where systems are 
> deployed with more than one initiation device or switch, they should 
> all be in close proximity so that emergency personnel can de-energize 
> all of the PV system circuits on the building within 10 seconds. 
> Further, labeling must clearly identify all of the initiation devices 
> and all of the steps required to complete rapid shutdown.
>
> Here’s a link to the complete article: http://bit.ly/1xuDxx7
>
> I hope this is of some assistance,
>
> David Brearley
> Senior Technical Editor, /SolarPro/ magazine
> NABCEP Certified PV Installation Professional
> david.brearley at solarprofessional.com 
> <mailto:david.brearley at solarprofessional.com>
> Direct: 541.261.6545
> Follow us on Twitter: @SolarPro
>
> Check out this AMAZING music video tribute to SolarPro: 
> http://bit.ly/1qfMCCh
>
>
>> On Feb 3, 2015, at 1:50 PM, re-wrenches-request at lists.re-wrenches.org 
>> <mailto:re-wrenches-request at lists.re-wrenches.org> wrote:
>>
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>> Today's Topics:
>>
>>   1. Re: Rapid Shut Down and the 10 Second Rule Questions (Mark Frye)
>>   2. Re: Rapid Shut Down and the 10 Second Rule Questions
>>      (Jerry Shafer)
>>   3. Re: Rapid Shut Down and the 10 Second Rule Questions (Mark Frye)
>>   4. How to isolate the array DC (Mark Frye)
>>   5. Re: How to isolate the array DC (Glenn Burt)
>>   6. Re: Rapid Shut Down and the 10 Second Rule Questions
>>      (Christopher Warfel)
>>   7. Re: How to isolate the array DC (Mark Frye)
>>   8. Re: Rapid Shut Down and the 10 Second Rule Questions
>>      (william at millersolar.com <mailto:william at millersolar.com>)
>>   9. Re: How to isolate the array DC (Jerry Shafer)
>>  10. Re: How to isolate the array DC (boB at midnitesolar.com 
>> <mailto:boB at midnitesolar.com>)
>>
>> *From:*Mark Frye <markf at berkeleysolar.com 
>> <mailto:markf at berkeleysolar.com>>
>> *To:*glenn.burt at glbcc.com <mailto:glenn.burt at glbcc.com>, RE-wrenches 
>> <re-wrenches at lists.re-wrenches.org 
>> <mailto:re-wrenches at lists.re-wrenches.org>>
>> *Date:*February 2, 2015 at 3:06:39 PM CST
>> *Reply-To:*RE-wrenches <re-wrenches at lists.re-wrenches.org 
>> <mailto:re-wrenches at lists.re-wrenches.org>>
>> *Subject:**Re: [RE-wrenches] Rapid Shut Down and the 10 Second Rule 
>> Questions*
>>
>>
>> I really do wonder then...
>>
>> Right now, you go up to the burning house and pull the meter, bingo, 
>> no AC anywhere. So why do we need the "kill" switch next to the 
>> service (or where ever).... IF you drive the roof top contactor with 
>> 120vac or with 24 vdc made from a power supply powered by 120vac. 
>> Either way, pull the meter, no more AC and no more power to the 
>> contactor coil on the roof, so DC limited to the location of the 
>> contactor.
>>
>> Not really sure how the requirement for the stop switch got into the 
>> Code.
>>
>> Mark Frye
>
>
>
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