Running PV wires in an attic/indoors/basement guidelines?

[Bluedog225]

Personally, I would not use mc4s on my house. Too many stories of shorts/fires.

It may be a good connector if properly installed and properly matched with the same brand male to female. But often mismatched from different manufacturers.

3m butt connectors throughout seem a lot safer. I might risk it on a ground mount system but not on a house.

 

[n2aws]

Thank you all for the feedback.
Other than the panels and mounting hardware, this is my initial list.

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Mind you, I'm not an electrician, so I'll let others declare if MC, armord cable, or BX is ok to use in an attic. However, I'd personally upgrade it to 10/2 instead of 12/2, that way if you ever change your array down the road (larger panels, more of them, etc) you don't have to worry about running all new wire for 1 wire guage difference. Buy once, cry once IMO.

 

[zanydroid]

I know Amazon is easy and fast but I would HIGHLY recommend buying from a solar supply house even if more expensive.

I did 90%in two orders through solar supply houses and electrical supply houses, and the balance in brand name parts off eBay.

 

[zanydroid]

The 12/2 MC will be subject to the PV-specific extra protection requirements due to its small size.

I believe 1” FMC is big enough to dodge those.

(MC/Flexible metal conduit is ok in attic if you follow the protection rules. Running board / guard strip type stuff)

 

[zanydroid]

For disconnect IMO plastic disconnects are the same price range as that likely unlisted Chinese brand.

 

[Cptx]

OK, so I've located a discreet location where I can run 10 AWG PV wires off the roof, and then discreetly run them in either flexible metal conduit or PVC conduit all the way around the house under the eaves behind gutters.

I am strongly considering this as it simplifies things (especially the final connection to the EG4 unit (which receives MC4), I don't have to drill a big hole in the roof, and I don't have to switch back and forth between PV and 10/2 and back again.

To keep wires off the roof (including the grounding wire, I would run them in conduit and support the conduit above the roof with support screw in conduit clamps/supports.

From the EG4 user manual.

 

[meager]

Thank you all for the feedback.
Other than the panels and mounting hardware, this is my initial list.

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If you are planning on getting this stuff inspected, be VERY weary about buying anything on Amazon. Do yourself a favor and ensure 100% that your breakers / disconnects are listed. Sure, they cost quite a bit more, but having to tear it all out and end up purchasing the "good" ones in the end is a hard pill to swallow. If you don't plan on having an inspection, just cowboy it and I'm sure it'll be perfectly fine.

 

[wheelman55]

Cowboy it. Very funny. Try explaining that to your insurance company after something fails and causes a fire.

 

[Cptx]

Thanks all for the advice.

What would be the preferred method with my situation (no inverter....5X400 watt in series roof panel array to EG4 outside compressor that has MC4 receiving connections if I want to avoid going through the roof with a junction box and then back out again?

Option one:
PV and ground wire from array to 10/2 MC via DC isolator, run the 10/2 MC around the house under the eaves/soffit to DC disconnect box adjacent to the EG4 outside compressor and then back again to PV (what's the best way to go back to PV cable from 10/2 MC ?) for the final connection to the EG4 outside compressor with MC4 receptacles......ground wire to house ground.

or

Option two:
Go PV and ground wire all the way around in flexible metal conduit (DC solar disconnect switch when the PV gets off the roof, then another DC disconnect box adjacent to the outdoor EG4 compressor).....ground wire to house ground.

or, is there a better option?

 

[Cptx]

This is a picture of the MC4 receptables on the 12K hybrid EG4 outside unit.
The instruction manual and the construction of the unit guide the consumer into utilizing PV cable as the final step if running directly off DC from the solar panel array.
If using PV cable anywhere except the roof isn't recommended by NEC, what is a reasonable modification or work around for that final step?

 

[zanydroid]

This is a picture of the MC4 receptables on the 12K hybrid EG4 outside unit.
The instruction manual and the construction of the unit guide the consumer into utilizing PV cable as the final step if running directly off DC from the solar panel array.
If using PV cable anywhere except the roof isn't recommended by NEC, what is a reasonable modification or work around for that final step?
View attachment 165434

PV is fine, it's single conductor PV hanging out by itself that is not fine.

Well this is EG4 tier stuff of the sort where they couldn't be bothered to change even a wiring compartment to be UL/NEC friendly so it may not be possible to be 100% compliant. In Mainland Chinese wiring standards (presumably these ACs are meant for some low density villages in Tibet, Xinjiang, or inner Mongolia) it is more acceptable to have some short lengths of exposed wire outside of conduits than it is in the US.

I guess if this thing is ETL listed (I see a mark for it in the screenshot) and says you can use bare conductors in the instructions you might get an out with the inspector and insurance.

Maybe put a waterproof electrical box (bell or PVC) close to the AC and run individual PV the last stretch through a two hole gland on the bell box. If there is a cable type that has individual PV conductors that would help. Another way is to sleeve it in some liquidtite and secure the end of the conduit somehow someway near the AC. Since EG4 hates you doing a good job you can't just screw it into a knockout on the AC.

No clue how I would handle the grounding for the metal parts.

I would not be surprised if this AC is not up to snuff with AFCI or GFP. For the AFCI case because it's not needed in most overseas places. For the GFP, probably there are rules overseas but I don't see a ground port for the PV side.

 

[Cptx]

Thank you very much for the detailed reply and excellent problem solving options.

 

[zanydroid]

No problem. What did support say?

You could potentially use an isolator switch next to the AC as the junction box. That would also let you transition to THHN while in conduit if it's a long run.

Don't remember if mentioned importance of matching MC4 brands but you should definitely follow that bullet point in the instructions. Unfortunately those instructions you shared above do not give an example NEC compliant installation.

 

[cs1234]

How do they expect you to match MC4 brands, with an inverter that comes with MC4 connectors on it? Do they sell / supply those exact MC4 connectors for you to make your own ends with?

 

[JRH]

Cowboy it. Very funny. Try explaining that to your insurance company after something fails and causes a fire.

I agree…Anyone that expects an insurence “ suit” not to look for any way to avoid payment as you didn’t comply with every known rule in existence is being silly.
build the system so that if it fails it won’t take your house..build a small climate controlled structure that contains it outside… only the AC wires enter the house…and do those to code with good skill.This is a tough goal to acheive unless you have unlimited money and sub it out or get all the inspections as required.
the insurence industry is not in business to help you any more than sharks are your friends.
J.

 

[zanydroid]

How do they expect you to match MC4 brands, with an inverter that comes with MC4 connectors on it? Do they sell / supply those exact MC4 connectors for you to make your own ends with?

As long as the MC4 brand is listed in the specs (and hopefully trust) or printed on the connector you can match.

There are also some MC4 compatible ones that are UL listed for multiple MC4 brands.

Now if you don't even know what brand it is on the inverter or AC... ?‍

 

[zanydroid]

Another thing that can be done is reterminating. On a MLPE or panel this is fairly easy (though one would probably want to get clearance that this does not void warranty. It is possible to do so). This can be done preemptively to meet code or reactively as a repair.

On this unit, I dunno. Need to look inside the wiring compartment to see how much spare wire there is and how the MC4 connector is attached to the knockout.

 

[Plum Crazy Rob]

I would not be surprised if this AC is not up to snuff with AFCI or GFP. For the AFCI case because it's not needed in most overseas places. For the GFP, probably there are rules overseas but I don't see a ground port for the PV side.

Hi Zany. As some of you are aware I had a PoCo run in where they investigated this unit then eventually waved it off as OK. One thing I thought I learned, was UL1741 compliance requires Arc Fault and Ground Fault - IS THAT CORRECT? Asking, not saying I know...

Can we trust China if it says it complies

 

[Cptx]

I’m staring to understand the issues with directly DC powered appliances that have a self contained MPPT and inverter (very difficult to stay within NEC guidelines; then there’s all the underutilized power)

For future such appliances, I wonder if there is an easy way to incorporate optional add on battery banks as part of the intended design. Doing so, may also enable such appliances to be in more accord with NEC, etc.

 

[Cptx]

Yes, there are different interpretations of the word “conforms”. ?