Sma rapid shut down

[SAP]

If I have multiple arrays on the roof, and I put my rapid shutdown at first array my emt connecting each array down stream will still have high currents in emt, is that ok are I'm I missing something

 

[ggunn]

If I have multiple arrays on the roof, and I put my rapid shutdown at first array my emt connecting each array down stream will still have high currents in emt, is that ok are I'm I missing something

Um, yeah, I think so. Rapid shutdown is about voltage, not current.

 

[Carultch]

If I have multiple arrays on the roof, and I put my rapid shutdown at first array my emt connecting each array down stream will still have high currents in emt, is that ok are I'm I missing something

Explain why you would still have high currents. Once the inverters are off, and assuming there are no faults, there is no serious current in any of the circuits. There might be currents due to an unshaded string feeding a shaded string, but these are usually small.

 

[GoldDigger]

Explain why you would still have high currents. Once the inverters are off, and assuming there are no faults, there is no serious current in any of the circuits. There might be currents due to an unshaded string feeding a shaded string, but these are usually small.

If a rapid shutdown must limit the total voltage leaving the array and there is not a panel level or series disconnect, then one way to limit the voltage is to short out the array. That would cause currents of up to Isc as long as the array is sunlit.
That current would flow in all of the conductors from the array to the shorting point. And breaking any wire would then expose high voltages at that point.

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[Carultch]

If a rapid shutdown must limit the total voltage leaving the array and there is not a panel level or series disconnect, then one way to limit the voltage is to short out the array. That would cause currents of up to Isc as long as the array is sunlit.
That current would flow in all of the conductors from the array to the shorting point. And breaking any wire would then expose high voltages at that point.

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Sounds like that would make the array even more dangerous.

 

[GoldDigger]

Sounds like that would make the array even more dangerous.

Yes and I am not saying any company actually does that.

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[PWDickerson]

If the sub-arrays are more than 20' apart from each other, you will need multiple rapid shutdown boxes. The rule is that any exterior conductor more than 10' from the array (includes conductors between sub-arrays) must be meet the safe voltage requirements in the prescribed amount of time once rapid shutdown is initiated.

 

[Carultch]

If the sub-arrays are more than 20' apart from each other, you will need multiple rapid shutdown boxes. The rule is that any exterior conductor more than 10' from the array (includes conductors between sub-arrays) must be meet the safe voltage requirements in the prescribed amount of time once rapid shutdown is initiated.

2 ft, in NEC 2017, since the radius away from the array is now a 1 ft limit. On the plus side, the prescribed amount of time is greater in 2017, and there's more guidance on where/how the initiation method can be.

 

[SAP]

If the sub-arrays are more than 20' apart from each other, you will need multiple rapid shutdown boxes. The rule is that any exterior conductor more than 10' from the array (includes conductors between sub-arrays) must be meet the safe voltage requirements in the prescribed amount of time once rapid shutdown is initiated.

Thank you,that makes sense, So each array covers 10 feet 2 arrays connecting =20 feet, so it's just like receptacles covers 6 feet of wall space if you have 2 receptacles then it =12 feet in between receptacles, Those SMA rapid shutdown equipment is not cheap