1000V PV Wire Protection

[CodeQuandary]

I've just posted a question in the general forum as to whether a rooftop installation qualifies as "inaccessible to unqualified persons" for the sake of mounting 1000V equipment. That's about inverters and such. I'm also curious about the module wiring: I'd say that, basically, there are really pitiful wire management options for PV module wiring -- for example, it seems like a wire tray wouldn't really qualify as guarding 1000V lines; conduit can't mate with the modules because they aren't built that way. I've seen a few pretty pics on the web but I'd be interested in hearing the experiences of anyone who has installed, designed, reviewed or inspected such systems (we don't have any around here yet). Thanks!

 

[GoldDigger]

I think you will find that most members will agree that the solution most acceptable to AHJs is to support the PV wire in any way that seems appropriate and then put access guards (wire mesh, metal or plastic panels, etc.) around the portion of the array where the wire is exposed.

 

[SolarPro]

Most AHJs clearly do consider many commercial rooftops to be "inaccessible to unqualified persons." Obviously, this is a case by case determination, and some AHJs may have more interpretation than others. However, I don't see much evidence that installers are having to protect the back-of-module wiring on commercial rooftops the same way they need to protect the back-of-module wiring in commercial or residential ground mounts.

Under NEC 2014, there's really nothing special required for 1,000 volt systems (other than 1,000-volt rated equipment). The Technical Correlating Committee universally replaced raised the 600 volt threshold to 1,000 volts throughout the NEC. So there are special requirements for systems and equipment over 1,000 volts. But systems with a maximum voltage of 1,000 volts are effectively treated no differently than 600 volt systems under earlier Code cycles.

 

[jaggedben]

...I'd say that, basically, there are really pitiful wire management options for PV module wiring -- ...

I wish I could disagree with that, but I really can't. I really wish a racking manufacturer or two would address this.

 

[augie47]

This has been allowed in this area:

 

[ggunn]

The Technical Correlating Committee universally replaced raised the 600 volt threshold to 1,000 volts throughout the NEC.

Except for the rooftops of 1 and 2 family dwellings, of course.

 

[SolarPro]

Except for the rooftops of 1 and 2 family dwellings, of course.

The TCP raised the voltage level throughout the Code. As part of the same cycle of revisions CMP 4 put in place a 600 V limit for residential applications.

 

[SolarPro]

This has been allowed in this area:
View attachment 15161

Right. But this is typically required in ground mount applications. The OP is asking about rooftop installations. I have seen little (no) evidence that AHJs are requiring metal mesh cages for PV source circuit conductors on commercial rooftops. Even when EPCs use lids on their cable trays on commercial rooftops, this is typically intended to reduce UV exposure rather than to limit accessibility (although it accomplishes both).

 

[pv_n00b]

I remember years ago on a private school roof installation a PV installer tried to make the case to the AHJ that the PV modules were not readily accessible, but at the same time the PV inverters on the roof were readily accessible. It was fun to watch.

 

[GoldDigger]

I remember years ago on a private school roof installation a PV installer tried to make the case to the AHJ that the PV modules were not readily accessible, but at the same time the PV inverters on the roof were readily accessible. It was fun to watch.

It is a mark of true intellectual flexibility to be able to hold two contradictory opinions at the same time.
It is also a useful skill for lawyers.

 

[augie47]

It is a mark of true intellectual flexibility to be able to hold two contradictory opinions at the same time.
It is also a useful skill for lawyers.

As In recall that was one of the skills I learned in Inspection 101