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
[email protected]
<mailto:[email protected]>
Direct: 541.261.6545
Follow us on Twitter: @SolarPro
Check out this AMAZING music video tribute to SolarPro:
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On Feb 3, 2015, at 1:50 PM, [email protected]
<mailto:[email protected]> 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
([email protected] <mailto:[email protected]>)
9. Re: How to isolate the array DC (Jerry Shafer)
10. Re: How to isolate the array DC ([email protected]
<mailto:[email protected]>)
*From:*Mark Frye <[email protected]
<mailto:[email protected]>>
*To:*[email protected] <mailto:[email protected]>, RE-wrenches
<[email protected]
<mailto:[email protected]>>
*Date:*February 2, 2015 at 3:06:39 PM CST
*Reply-To:*RE-wrenches <[email protected]
<mailto:[email protected]>>
*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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