Fronius Rapid Shutdown Box Single String

Fronius Rapid Shutdown Box Single String
Fronius Rapid Shutdown Box Single String
$245.00 List price $315.00

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Item code Brand name Model number
FRNRAPIDSHUT Fronius Rapid Shutdown Box Single


Rapid Shutdown Box
For Galvo and Primo TL Inverters

The new Fronius Rapid Shutdown Box provides the ultimate solution for NEC 2014 code compliance and enhances rooftop and firefighter safety. The 2014 NEC requires a rapid shutdown function for PV systems on buildings. With the Fronius Rapid Shutdown Box, Fronius offers a reliable and easy-to-install solution for all single phase SnapINverters from 1.5 kW to 8.2 kW. Directly connected to the inverter through the same DC conduit as the DC homeruns, the Fronius solution minimizes the number of boxes needed providing ease of installation. No extra power supply or ground level hardware needed, reducing system cost. The Rapid Shutdown is triggered whenever AC is not present, and the DC lines are rapidly discharged by the inverter.


  • Single String operation only- need one box per string
  • DC Powered by the array (max 3W)
  • NEMA 3R Enclosure
  • Temperature range - -40° to 140 ° F
  • Max input current - 12.5A
  • Max voltage- 600V
  • Max DC homerun wire size - AWG 10
  • DC input wire size - AWG 10 to AWG 12
  • Max communication wire size - AWG 14
  • Number of conduit ports - 2 (conduit size 3/4")
  • UL1741:2010, FCC Part 15 Class B



Is anything required other than the Fronius Rapid Shutdown Box itself ? Other than the Fronius Rapid Shutdown Box, only a Fronius SnapINverter (Galvo or Primo) is required.

Does the Fronius Rapid Shutdown Box mount on the roof or in the attic? The Fronius Rapid Shutdown Box comes with a universal mounting bracket that allows installation on most common racking systems as well as on the roof.

Does this solution require the main AC breaker be shut off for the box to react? Is there any way of disconnecting the DC voltage at the box? Shutting off AC activates the rapid shutdown function. The dual string version of the Fronius Rapid Shutdown Box will have a DC disconnect switch built-in. The single string version does not have the DC Disconnect built-in.

Do I need one Fronius Rapid Shutdown Box per string? This is correct. Please be aware that each independently operated MPPT needs its very own Fronius Rapid Shutdown Box. For example, if there is a system with 2 strings attached to the two individual DC inputs of a small Fronius Primo unit, two single string Fronius Rapid Shutdown Boxes should be deployed. (** Dual string box coming Fall 2015)

Is the Fronius Rapid Shutdown Box compatible with the Fronius IG Plus Advanced or prior IG models? No, it is not. This is only compatible with the Galvo and Primo SnapINverters. Also be aware that the Fronius IG Plus line does not meet the new NEC 2014 ground faultdetection requirements.

How is an AC shut off in correspondence with the rapid shutdown function? What happens on the AC side, if DC is off? The Fronius Rapid Shutdown Solution is triggered by AC being shut off. AC shut off - inverter shuts down - little relay in inverter goes into off (default position) - RSB(Rapid Shutdown Box) signal lines go to RSB off status - RSB shuts down the connection between RSB and the Fronius SnapINverter, (no matter how much energy is available from the panels). This “chain reaction” is a one-way operation. There is no influence on AC in the other direction what so ever. If the inverter falls asleep because of low voltage/power on the array, AC is still on and not affected. The same is true in case the DC disconnect is put into the off position. Conclusion: the inverter stays connected to AC all the time (as long as the grid quality parameters are good), and feeds in. But if AC is off, the homeruns will be de-energized within 10 seconds.


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