Microinverters in the attic again

[MikeNZ]

Hi Guys,

Some of you may remember my idea about putting enphase microinverters in some enclosures and wiring them together in an attic and seeing what issues we may come across doing so. those have been addressed but now we have a new issues we would like some suggestions on, how to connect them to the MDB.
I know it has to be a dedicated circuit, question is could we put a plug and lead on these enclosures and plug them into pre-installed outlets in the attic?
would these outlets have to be a special sort so no normal appliances could be plugged into them?
We were hoping that being an attic it's unlikely enough for appliances to be plugged into these outlets that we could use standard 15A sockets to plug these boxes into.

 

[jaggedben]

WHY?

If you have any kind of legitimate reason to be doing this then I suggest you seek an arrangement with the AHJ wherein your experimental location is classified as some kind of laboratory and is exempt from normal code requirements.

Otherwise you're not supposed to have plug and cord connected interactive inverters.

 

[ggunn]

Hi Guys,

Some of you may remember my idea about putting enphase microinverters in some enclosures and wiring them together in an attic and seeing what issues we may come across doing so. those have been addressed but now we have a new issues we would like some suggestions on, how to connect them to the MDB.
I know it has to be a dedicated circuit, question is could we put a plug and lead on these enclosures and plug them into pre-installed outlets in the attic?
would these outlets have to be a special sort so no normal appliances could be plugged into them?
We were hoping that being an attic it's unlikely enough for appliances to be plugged into these outlets that we could use standard 15A sockets to plug these boxes into.

You could probably make it work electrically but at the very least I believe you would void warranties as well as UL listings for the equipment, and code dictates that you install equipment according to manufacturers' instructions. Why would you want to do such a thing?

 

[MikeNZ]

the inverters are designed to be plugged into each other using the proprietary Enphase Q-cable, all we effectively want to do is replace that q-cable with more-or-less standard plugs and sockets for easier installation in an attic. Remember these inverters are not mounted on the roof they are in separate enclosures in the attic space. Electrically speaking the wiring is identical to how the manufacturers recommend, only the method is changed to be more installer friendly in an attic. As for the "you're not supposed to have plug and cord connected interactive inverters" argument, I cannot find anywhere in the NEC that states that, only that they have a dedicated circuit, which we were hoping to satisfy with using less-than-standard sockets. There are existing plug-and-play solar systems that use interactive inverters that plug into a standard socket, the main argument I often see against these systems is the dedicated circuit rule.

 

[ggunn]

the inverters are designed to be plugged into each other using the proprietary Enphase Q-cable, all we effectively want to do is replace that q-cable with more-or-less standard plugs and sockets for easier installation in an attic. Remember these inverters are not mounted on the roof they are in separate enclosures in the attic space. Electrically speaking the wiring is identical to how the manufacturers recommend, only the method is changed to be more installer friendly in an attic. As for the "you're not supposed to have plug and cord connected interactive inverters" argument, I cannot find anywhere in the NEC that states that, only that they have a dedicated circuit, which we were hoping to satisfy with using less-than-standard sockets. There are existing plug-and-play solar systems that use interactive inverters that plug into a standard socket, the main argument I often see against these systems is the dedicated circuit rule.

Something we keep asking is "why?"

 

[jaggedben]

the inverters are designed to be plugged into each other using the proprietary Enphase Q-cable, all we effectively want to do is replace that q-cable with more-or-less standard plugs and sockets for easier installation in an attic.

Maybe you should just use Q cable then. They offer field installable plugs.

Remember these inverters are not mounted on the roof they are in separate enclosures in the attic space. Electrically speaking the wiring is identical to how the manufacturers recommend, only the method is changed to be more installer friendly in an attic.

Most times I'd rather be on a roof than in an attic.

As for the "you're not supposed to have plug and cord connected interactive inverters" argument, I cannot find anywhere in the NEC that states that, only that they have a dedicated circuit, which we were hoping to satisfy with using less-than-standard sockets. There are existing plug-and-play solar systems that use interactive inverters that plug into a standard socket, the main argument I often see against these systems is the dedicated circuit rule.

It's not in the NEC, but I believe it's in the UL standard. Those 'existing' inverters are not listed or are perpetrating some other kind of fraud.

 

[ggunn]

... There are existing plug-and-play solar systems that use interactive inverters that plug into a standard socket, the main argument I often see against these systems is the dedicated circuit rule.

Seriously? There are so many things wrong with those "systems" I am surprised that they are even available. You cannot legally install one anywhere the NEC is enforced, and that's a good thing.

 

[ramsy]

Seriously? There are so many things wrong with those "systems" I am surprised that they are even available. You cannot legally install one anywhere the NEC is enforced, and that's a good thing.

Unless you hire an NRTL representative to come out and do a field certification.

The NRTL reps hang out at local IAEI meetings, pass out flyers, compete over field certs, make presentations to ID counterfeit equipment labels, and beg the membership to report listing violations.

One Field certification can also be designed to apply across duplicate locations.

 

[tortuga]

As for the "you're not supposed to have plug and cord connected interactive inverters" argument, I cannot find anywhere in the NEC that states that,

MikeNZ: As soon as your inverter is attached its no longer portable and its now part of the fixed wiring of a structure.
See NEC 400.12 Unless specifically permitted in say 400.10, 690 or 705 flexible cables, flexible cord sets, and power supply cords
shall not be used 'as a substitute for the fixed wiring of a structure'.
See also 110.3(B)

 

[ggunn]

What we have repeatedly asked but has never been answered is the question of why anyone would want to do this. For one thing, having a set of conductors penetrating the roof for every module in the array sounds ludicrous to me.

 

[MikeNZ]

Maybe you should just use Q cable then. They offer field installable plugs.

You cant install Q cable in an attic, we've checked.

Most times I'd rather be on a roof than in an attic.

The idea with our system is that only the roofer installing our product needs to go onto the roof, as our product IS the roofing product.
This means all the electricians work will be in the attic or at the panel, never on the roof.

It's not in the NEC, but I believe it's in the UL standard. Those 'existing' inverters are not listed or are perpetrating some other kind of fraud.

I figured there would be a rule somewhere that disallowed the plug-in inverter idea, so we shall consider that idea abandoned and just wire the boxes permanently.

 

[MikeNZ]

MikeNZ: As soon as your inverter is attached its no longer portable and its now part of the fixed wiring of a structure.
See NEC 400.12 Unless specifically permitted in say 400.10, 690 or 705 flexible cables, flexible cord sets, and power supply cords
shall not be used 'as a substitute for the fixed wiring of a structure'.
See also 110.3(B)

Thanks Tortuga, this is a good reason to abandon the plug-in inverter train of thought.

 

[MikeNZ]

What we have repeatedly asked but has never been answered is the question of why anyone would want to do this. For one thing, having a set of conductors penetrating the roof for every module in the array sounds ludicrous to me.

I would definitely agree for a standard solar panel installation, however our system is thin-film BIPV, so there's not a space on the roof for the inverters even if we wanted them up there, and our penetration solution is (which should never get wet anyway) absolutely watertight.

 

[MikeNZ]

Unless you hire an NRTL representative to come out and do a field certification.

The NRTL reps hang out at local IAEI meetings, pass out flyers, compete over field certs, make presentations to ID counterfeit equipment labels, and beg the membership to report listing violations.

One Field certification can also be designed to apply across duplicate locations.

While that would be an excellent idea if this were a one-off install, this is a product currently in development for mass production and installation, we will have everything tested and certified before roll-out.

 

[MikeNZ]

for those interested, more info on the system can be found in this thread:

Micro-Inverters in the Attic

Hi all, I am looking to install a PV system on my roof using micro-inverters, but my situation wont allow for these inverters to be mounted on the roof, so i want to install them in the attic below the array and join them together there. Im aware that the DC cabling inside the attic is required...

forums.mikeholt.com