RAPID SHUTDOWN, and CODE

[inforaj]

Per the NEC, the Rapid shutdown device was 1st introduced in 2014 for rooftop solar systems. The procurement team member called to AHJ office and asked about the requirements. The AHJ staff said we don't require a Rapid shutdown for solar systems.

Now the operation and procurements teams blame the design engineer for the increasing costs of all projects and pushing it to remove them from all projects.

We explained, in detail, how this device protects the modules from any faults or short circuits. Can you please advise about this?

I appreciate any help you can provide.

 

[ggunn]

If the AHJ is not enforcing rapid shutdown it may be difficult to justify the expense of including it. Whether rapid shutdown compliance actually contributes to the safety of a PV system has been a matter of some debate. It does not, however, protect modules from faults or short circuits; it was brought in ostensibly as a safety measure for firefighters who may be called to extinguish a rooftop fire where there is a PV system present.

 

[jaggedben]

Well too much to really unpack here, but I can't resist trying...

First, I wouldn't be taking this alleged phone call for being worth much. Did anyone look up the actual code? Unless the AHJ is not yet bound by the 2014 code, or has a legal amendment to the state code, or something like that ... then what someone said over then phone is pretty worthless. The person in the office they talked to may have not understood the question or had the authority to answer it. If RS is in the code that's officially adopted an inspector can still require it. Personally I'd want to get it in writing, get stamped plans and get a passed inspection on one project before changing any others. And even then maybe it all goes well for a while until someone catches on to it and the AHJ changes their mind and then you have to rebuild a project, or several, at huge cost in labor and opportunity.

Second, if your company is big enough to have 'teams' then how many AHJs do you work with, and which ones don't require it? How many offices did they call? Why change something on all projects instead of just for this one AHJ?

Anyway, to get more to the question you asked...
Here are some potential risks I see that would have to be offset by the savings in equipment cost, which may be more or less depending one what equipment you're actually using, and which may or may not, as ggunn said, justify the extra equipment cost.

> The devices used for rapid shutdown tend to make arrays safer for those installing, so some lessened risk of injury and equipment damage and the associated cost of those things (but depends on details) .

> RS devices tend to come with other monitoring and production benefits that will save labor on service calls (also depends on details).

> If, god forbid, there was a fire, and a fire fighter or anyone else got an electrical injury from the PV, and it was found that the legally applicable code required RS and you didn't install it, the lawyers for the injured party will have a field day with that regardless of what the AHJ enforced. More likely the AHJ gets sued as co-defendant than your company gets let off the hook. (It could be especially bad for your company if any evidence were discovered that showed that your company knew that the AHJ ought to be enforcing RS, but there was some kind of verbal conversation that they wouldn't enforce it for you.)

 

[ggunn]

Well too much to really unpack here, but I can't resist trying...

First, I wouldn't be taking this alleged phone call for being worth much. Did anyone look up the actual code? Unless the AHJ is not yet bound by the 2014 code, or has a legal amendment to the state code, or something like that ... then what someone said over then phone is pretty worthless. The person in the office they talked to may have not understood the question or had the authority to answer it. If RS is in the code that's officially adopted an inspector can still require it. Personally I'd want to get it in writing, get stamped plans and get a passed inspection on one project before changing any others. And even then maybe it all goes well for a while until someone catches on to it and the AHJ changes their mind and then you have to rebuild a project, or several, at huge cost in labor and opportunity.

Second, if your company is big enough to have 'teams' then how many AHJs do you work with, and which ones don't require it? How many offices did they call? Why change something on all projects instead of just for this one AHJ?

Anyway, to get more to the question you asked...
Here are some potential risks I see that would have to be offset by the savings in equipment cost, which may be more or less depending one what equipment you're actually using, and which may or may not, as ggunn said, justify the extra equipment cost.

> The devices used for rapid shutdown tend to make arrays safer for those installing, so some lessened risk of injury and equipment damage and the associated cost of those things (but depends on details) .

> RS devices tend to come with other monitoring and production benefits that will save labor on service calls (also depends on details).

> If, god forbid, there was a fire, and a fire fighter or anyone else got an electrical injury from the PV, and it was found that the legally applicable code required RS and you didn't install it, the lawyers for the injured party will have a field day with that regardless of what the AHJ enforced. More likely the AHJ gets sued as co-defendant than your company gets let off the hook. (It could be especially bad for your company if any evidence were discovered that showed that your company knew that the AHJ ought to be enforcing RS, but there was some kind of verbal conversation that they wouldn't enforce it for you.)

I agree with all of that, but the OP said, "...this device protects the modules from any faults or short circuits", which is not the case. Protecting the modules is neither the reason for rapid shutdown nor what it does.

 

[pv_n00b]

I would be cautious and get it in writing. A phone call is meaningless for this.
If you build the system without RSD and some firefighter is hurt or killed later what's going to be your defense in court? "We did not build an NEC compliant system because the AHJ did not require it" may or may not override the prosecution holding up the NEC and saying that the system did not meet the safety requirements in this book that everyone else follows and someone died because of it. Good luck beating that.

 

[ron]

Since the adopted NEC is the minimum required for a project, I design projects over the minimum where I think it is needed, such as rapid shutdown in jurisdictions that may not be up to date.
If the client wants to talk about it, we can, but they would need to go to another Engineer to get it off the drawings.