Universal cable for AC solar systems

[billsharp35]

Using Section 705 with AC microinverter solar panels.

Is there a universal affordable cable to run inside, outside, attic, on the exposed roof, etc, from the electrical panel to the AC solar panels ?.

 

[jaggedben]

No.

 

[iMuse97]

In an industrial setting you'd be able to use tray cable the whole way, but you probably knew that.

In or on a residence or commercial building, you'll have to follow various codes and use various materials to get through the transitions you've mentioned.

 

[augie47]

I was waiting on one of the Solar guys to step in, but in the meantime, in my limited experience, the only one I have found is a cable with RHW/USE-2 ratings
690.31 allows the USE-2 and RHW is an acceptable conductor for most raceway installations. In addition, the cable I see, manufactured by Southwire, is sunlight resistant.

 

[jaggedben]

690.31 allows the USE-2 ...

...for PV source circuits. Meaning DC circuits, not AC circuits feeding micro-inverters. And the allowance is specifically for single conductor cable. So 690.31 has no bearing on the OP's question.

What the OP is asking for is a 4-wire multiconductor cable, including a minimum #8 ground for a GEC, that is sunlight resistant and rated to 90C in wet locations, and allowed to be used on the interior of a building (and perhaps he meant without a raceway?). I'm not aware of a particular product that meets all these requirements; not even the cabling that Enphase uses does. And I'm certain that if such a product does exist, it's not 'affordable' at this point in history.

 

[billsharp35]

I played it safe, but don't agree AC solar is a lot safer than DC

I played it safe, but don't agree AC solar is a lot safer than DC

AC microinvertors panels & section 705 are so new, if they don't know they just refer back to section 690. When I installed the inspectors did not know enough & wanted me to do some of the section 690 rules, I politely showed them 705 rules & how the Mike Holt solar video's explained it. But I still think section 705 needs a lot of work. I used all the best rules of 690 / 705 & I know some were overkill, I didn't care because this is my personal house. I just think that there is some cost that can be cut safely when installing AC panels from section 705.

EX: 690 has us running pipe & 690.31 E 1 pipe min 10" below roof line for firemen.
AC microinvertors drop out within a second of main power grid loss, unlike DC. AC power relays kick back in after the power grid or main power source is on for 5 minutes unlike DC. My point is why piping, 10" rule etc, when I'm walking over all the over AC circuits in my attic, there is no difference. I'm just backfeeding.
EX: I ran pvc piping from the panel to J box, with a expansion coupling in the attic. From the J box a 6' flex whip to the panels. I pulled THWN-2 stranded wire. This is all I could find approved & affordable.
I put a pull out disconnect box on the roof, didn't have to because 705.12. D1 covers me with a breaker, but I needed a weatherproof j box to connect my flex to there approved exposed to weather cable that lays on the roof, under the panels, get my point again. THWN-2 strained and all the wire was completely watertite & not getting any sunlight, THWN-2 is overkill in my opinion.

What I do like is 705.10 directory, 690.5 C markings, 690.31 E 3 marking boxes, etc, 690.31 E4 every 10' labels & markings, 690.4 B 1-4 E indentification, and my favorite disclaimer 705.30 A just ref 690.
I got no problem indentifing two power sources & always being safe, I just think there needs to be an affordable color coded cable, to cut down cost, because the solar guys have done a good job making affordable alternative energy and the NEC needs to help also. Everybody needs to be a little greener and cost was the biggest hold up.

Just some thoughts of mine & thanks for the feedback, I 've been checking into USE-2 RHW cable.

Take Care Bill

I was waiting on one of the Solar guys to step in, but in the meantime, in my limited experience, the only one I have found is a cable with RHW/USE-2 ratings
690.31 allows the USE-2 and RHW is an acceptable conductor for most raceway installations. In addition, the cable I see, manufactured by Southwire, is sunlight resistant.

 

[jaggedben]

I played it safe, but don't agree AC solar is a lot safer than DC

I think you meant to put a period between 'agree' and 'AC'? Sounds like you think AC is safer.

EX: 690 has us running pipe & 690.31 E 1 pipe min 10" below roof line for firemen.
AC microinvertors drop out within a second of main power grid loss, unlike DC. ...

You are correct that the requirements of 690.31(E) should not be applied to micro-inverter branch circuits. 690.31(E) applies to PV source and output circuits, which is to say DC circuits from solar panels.

EX: I ran pvc piping from the panel to J box, with a expansion coupling in the attic. ...

Most people use EMT with some FMC if necessary. It's quite possible that you violated 352.12 (D) by putting PVC in a location where ambient temperatures may exceed 50C (i.e. your attic).

THWN-2 is overkill in my opinion.

It's usually not, when you do all the proper calculations that account for ambient temperature.

I just think there needs to be an affordable color coded cable...

I agree that would be nice... OTOH, if you know the proper wiring methods, you can go a long way with NM and bare #8. Just not all the way to the roof.

I 've been checking into USE-2 RHW cable.

As I said above, this is permitted for single conductor cables for DC circuits. I don't think it would be permitted for AC, or make practical or economic sense.

 

[billsharp35]

Thanks, just trying to make it more affordable & user friendly.

Thanks, just trying to make it more affordable & user friendly.

Thanks for all the feedback, not trying to rub anybody wrong, I just think that section 705 needs tweaking and some new cables & rules to apply. The more cost can be cut down, the more people will go greener, AC solar is some really good work. I never condone cutting corners, not using the code to the letter or being unsafe. I'm not the smartest, I'm just trying to look for better ways and thats why I asked the question on the forum

Take care Bill

Most people use EMT with some FMC if necessary. It's quite possible that you violated 352.12 (D) by putting PVC in a location where ambient temperatures may exceed 50C (i.e. your attic).

Your right but, those attics are tough, I'm 46 and don't bend so good anymore and pvc probably cut half my time down in the attic, I was a few days installing piping in the attic. ( You get my point ) I checked and I do not exceed 50C before I installed. Rule of thumb, houses are 70 to 72 degrees, if the attic is correctly insulated, roof vented or power vented, soffit vents are not blocked. An attic is only 20 degrees above room temperature. Also installing a full solar array system covers most of my roof, which also blocks the sun penetration. 50C is approx 122 F and checked my attic during this record heat 95 F.

It's usually not, when you do all the proper calculations that account for ambient temperature.

I was mostly talking about the THWN-2, because none of the wire is wet or exposed, so why -2

I think you meant to put a period between 'agree' and 'AC'? Sounds like you think AC is safer.



You are correct that the requirements of 690.31(E) should not be applied to micro-inverter branch circuits. 690.31(E) applies to PV source and output circuits, which is to say DC circuits from solar panels.

Most people use EMT with some FMC if necessary. It's quite possible that you violated 352.12 (D) by putting PVC in a location where ambient temperatures may exceed 50C (i.e. your attic).

It's usually not, when you do all the proper calculations that account for ambient temperature.

I agree that would be nice... OTOH, if you know the proper wiring methods, you can go a long way with NM and bare #8. Just not all the way to the roof.

As I said above, this is permitted for single conductor cables for DC circuits. I don't think it would be permitted for AC, or make practical or economic sense.

 

[jaggedben]

I just think that section 705 needs tweaking and some new cables & rules to apply.

New types of cabling wouldn't go in 705. It would go in chapter 3. I agree that products and code for solar ought to evolve.

if the attic is correctly insulated, roof vented or power vented, soffit vents are not blocked. An attic is only 20 degrees above room temperature.

Trust me, I've been in some attics that were neither of those things!

50C is approx 122 F and checked my attic during this record heat 95 F.

That's good then.

I was mostly talking about the THWN-2, because none of the wire is wet or exposed, so why -2

Dash 2 just means that it's rated for 90C. THWN-2 is not suitable to be exposed in any case. With the various required deratings for conduit runs on the roof, often dash 2 is required for solar systems.