Rapid Shutdown SMA Core 1

[electro7]

I just wanted to confirm that I'm reading 690.12 correctly. If I install an SMA Core 1 within 3ft of the array, I do comply with the Rapid ashutdown requirements for building roofs, correct? It is listed for rapid shutdown I see in the spwc sheet - "SunSpec PLC signal for rapid shutdown."

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[ggunn]

I just wanted to confirm that I'm reading 690.12 correctly. If I install an SMA Core 1 within 3ft of the array, I do comply with the Rapid ashutdown requirements for building roofs, correct? It is listed for rapid shutdown I see in the spwc sheet - "SunSpec PLC signal for rapid shutdown."

Sunspec is a protocol whereby the inverter supplies a "keep alive" signal on the DC conductors to communicate with rapid shutdown devices on the modules such as the SMA JMS-F for as long as the inverter is running. These devices disconnect the modules from the DC bus when the inverter, which can be anywhere, shuts down and the "keep alive" signal goes away. Without the RS devices on the modules, Sunspec does nothing.

The three foot rule you refer to is a completely different issue, and it may or not be applicable, depending on which NEC version the AHJ is enforcing. If it is applicable, you don't need the RS devices on the modules and Sunspec is not relevant.

 

[BackCountry]

I just wanted to confirm that I'm reading 690.12 correctly. If I install an SMA Core 1 within 3ft of the array, I do comply with the Rapid ashutdown requirements for building roofs, correct? It is listed for rapid shutdown I see in the spwc sheet - "SunSpec PLC signal for rapid shutdown."

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I believe you may be hunting at UL3741, which requires an assembly (racking specifically) that’s compliant and listed. We do it often and bypass RSD as long as it’s compliant. My preferred combination is Unirac and SMA.

 

[jaggedben]

3ft is only relevant if the conductors enter the building. Otherwise it's 1ft. But as others have alluded to, simply using this inverter and placing it 1ft from the array is not sufficient for compliance.

 

[electro7]

Okay, I'm confused by that code section and need to read through it again. Not fully understanding the wording and what it's saying and I haven't had to use it much working with optimizers and MIs.

So on a commercial rooftop system is there any way to get around installing MIs or optimizers or RSDs? What is UL3741- I am not understanding that either and what it has to do with racking products?

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[ggunn]

So on a commercial rooftop system is there any way to get around installing MIs or optimizers or RSDs? What is UL3741- I am not understanding that either and what it has to do with racking products?

You are not alone in that respect.

 

[jaggedben]

In a nutshell, UL 3741 means the racking system has been tested together with panel strings to show that the hazard to firefighters wearing typical PPE is within acceptable limits. It eliminates the need for rapid shutdown electronics, but instructions must be followed to a 't'. Only relatively recently (last 2-3 years) has the standard been published and some manufacturers started to get listed to it.

There have been some discussions here, try a search. For example:

Rapid shutdown options

Ive dont quite a bit of flat roof PV, but it was before the RS requirements, and since then Ive specialized in ground mount so didnt have to deal with it there either. I have some possible flat ballasted stuff coming up, would someone mind giving me a quick rundown of the options? This is...

forums.mikeholt.com

 

[electro7]

Do you know what the racking system has to do with firefighter safety plus rapid shutdown?

I read most of that thread and didn't learn much about the specifics of UL3741.

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[electro7]

In a nutshell, UL 3741 means the racking system has been tested together with panel strings to show that the hazard to firefighters wearing typical PPE is within acceptable limits. It eliminates the need for rapid shutdown electronics, but instructions must be followed to a 't'. Only relatively recently (last 2-3 years) has the standard been published and some manufacturers started to get listed to it.

There have been some discussions here, try a search. For example:

Rapid shutdown options

Ive dont quite a bit of flat roof PV, but it was before the RS requirements, and since then Ive specialized in ground mount so didnt have to deal with it there either. I have some possible flat ballasted stuff coming up, would someone mind giving me a quick rundown of the options? This is...

forums.mikeholt.com

Do you know what the racking system has to do with firefighter safety plus rapid shutdown?

I read most of that thread and didn't learn much about the specifics of UL3741.

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[BackCountry]

Do you know what the racking system has to do with firefighter safety plus rapid shutdown?

I read most of that thread and didn't learn much about the specifics of UL3741.

Sent from my SM-G998U using Tapatalk

UL3741 specifies that the racking, inverter, and some of the BOS are a listed assembly. You get a free pass on RSD if you follow the requirements (array size, inverter proximity to array, etc.)

The key reasons for this are reduced number of connectors because there’s no MLPE, pre defined conductor routing that’s contained within the footprint of the array, so less firefighter shock hazard. Insulation (more specifically meaning that the wiring is not outwardly exposed). This all gets tested on a pass fail basis and if it passes all of the safety elements then it meets UL3741 as long as you use listed components, of which the detail level is down to the zip ties in some cases.

 

[electro7]

UL3741 specifies that the racking, inverter, and some of the BOS are a listed assembly. You get a free pass on RSD if you follow the requirements (array size, inverter proximity to array, etc.)

The key reasons for this are reduced number of connectors because there’s no MLPE, pre defined conductor routing that’s contained within the footprint of the array, so less firefighter shock hazard. Insulation (more specifically meaning that the wiring is not outwardly exposed). This all gets tested on a pass fail basis and if it passes all of the safety elements then it meets UL3741 as long as you use listed components, of which the detail level is down to the zip ties in some cases.

Thanks. So where do I find more information about what is considered listed assemblies and such? Are there guidelines I can find somewhere that explain what zip ties (for example) to use, etc?

I think this is great. Doing away with all of the connections and devices that are required with RSDs, I think, is a good thing and safer. It seems from my experience that most electrical failures occur at the connection points.

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[BackCountry]

Thanks. So where do I find more information about what is considered listed assemblies and such? Are there guidelines I can find somewhere that explain what zip ties (for example) to use, etc?

I think this is great. Doing away with all of the connections and devices that are required with RSDs, I think, is a good thing and safer. It seems from my experience that most electrical failures occur at the connection points.

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Yes, the racking manufacturers are where to start.

For flat roof, I’d scope out Unirac.

 

[electro7]

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