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Secure Power on SMA inverter and NEC 690.12 2017 compliance

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  • Secure Power on SMA inverter and NEC 690.12 2017 compliance

    Grid-tied inverter SB7.7-1SP-US-40 provides 2kW of Secure Power via separate outlet if grid goes down. It needs to be activated via separate switch. However our municipality requires NEC 690.12 2017 compliance for Rapid Shutdown

    Did anybody find technical and still legal solution to meet NEC requirements and keep Secure Power?

    Panels must have TS4-S, TS4-O or TS4-F modules to keep them alive via signal transmitter when grid it on and initiate Rapid Shutdown if grid is off

    RSS transmitter with TS4-F or "Tigo Cloud Connect" with "Gateway" (Transmitter for TS4-S/O) should receive power from grid. In such case when grid is off or A/C Disconnect off, then no signal to TS4 modules and system goes to Rapid Shutdown mode

    I believe It's technically feasible to feed those activation devices via cheap UPS block with batteries and install a separate Disconnect switch for rapid shutdown breaking that power in case of emergency. It looks like that should work to keep Secure Power and still meet NEC 2017 requirements (with manual Rapid Shutdown initiation)

    Can it be approved by city inspectors? If not, can somebody epxlain why?

    Any other solutions for Secure Power with NEC 2017 compliance?

  • #2
    Originally posted by phx View Post
    Grid-tied inverter SB7.7-1SP-US-40 provides 2kW of Secure Power via separate outlet if grid goes down. It needs to be activated via separate switch. However our municipality requires NEC 690.12 2017 compliance for Rapid Shutdown

    Did anybody find technical and still legal solution to meet NEC requirements and keep Secure Power?

    Panels must have TS4-S, TS4-O or TS4-F modules to keep them alive via signal transmitter when grid it on and initiate Rapid Shutdown if grid is off

    RSS transmitter with TS4-F or "Tigo Cloud Connect" with "Gateway" (Transmitter for TS4-S/O) should receive power from grid. In such case when grid is off or A/C Disconnect off, then no signal to TS4 modules and system goes to Rapid Shutdown mode

    I believe It's technically feasible to feed those activation devices via cheap UPS block with batteries and install a separate Disconnect switch for rapid shutdown breaking that power in case of emergency. It looks like that should work to keep Secure Power and still meet NEC 2017 requirements (with manual Rapid Shutdown initiation)

    Can it be approved by city inspectors? If not, can somebody epxlain why?

    Any other solutions for Secure Power with NEC 2017 compliance?
    I've given this some thought; I have not yet had the opportunity to implement this idea but the signal generator for the TS4s is powered by 12v IIRC. You could put a small 12v battery in parallel to the power supply such that it can provide power during an outage for a short time. The 12v power supply can run though an 'E' stop and that would initiate rapid shutdown regardless of whether SPS is initiated or not.

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    • #3
      Originally posted by nwdiver View Post

      I've given this some thought; I have not yet had the opportunity to implement this idea but the signal generator for the TS4s is powered by 12v IIRC. You could put a small 12v battery in parallel to the power supply such that it can provide power during an outage for a short time. The 12v power supply can run though an 'E' stop and that would initiate rapid shutdown regardless of whether SPS is initiated or not.
      It looks like suggested setup with UPS or backup battery meets 2017 690.12 C3 provisions if signal generator connected to backup battery via "Initiation Device" mentioned there. I.e. just simple disconnect switch for rapid shutdown clearly indicating "on" or "off" position

      However I guess inspector might try to deny project on grounds of 690.12.D telling that battery (or UPS) is not certified for providing rapid shutdown protection since it such case becomes a part of rapid shutdown cirquitry. Any ideas?

      I'm weighting pros and cons. Is it worth to try getting permit with idea suggested above? Or better give up surrendering luxury of Secure Power? I wish SMA, Tigo or other vendors posted well-documented solutions for [B]Secure Power with NEC 2017 690.12 compliance. [/B]The only I could find in SMA invertor instruction, if you install communication module for TS4 into slot in invertor, Secure Power will be disabled. It looks like similar topic was never discussed on any other forums. Or at least I couldn't find any references

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      • #4
        Originally posted by phx View Post

        It looks like suggested setup with UPS or backup battery meets 2017 690.12 C3 provisions if signal generator connected to backup battery via "Initiation Device" mentioned there. I.e. just simple disconnect switch for rapid shutdown clearly indicating "on" or "off" position

        However I guess inspector might try to deny project on grounds of 690.12.D telling that battery (or UPS) is not certified for providing rapid shutdown protection since it such case becomes a part of rapid shutdown cirquitry. Any ideas?
        I would just ask the inspector. If the 'E' stop clearly kills power to the signal generator I don't see how that wouldn't be compliant.

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