Romex for DC run

[augie47]

690.31 Methods Permitted.

(A) Wiring Systems. [COLOR=#ff0000]All raceway and cable wiring methods included in this Code[/COLOR], other wiring systems and fittings specifically listed for use on PV arrays, and wiring as part of a listed system [COLOR=#ff0000]shall be permitted[/COLOR]. Where wiring devices with integral enclosures are used, sufficient length of cable shall be provided to facilitate replacement.

In the '17 Code there is an important 2nd paragraph.

[tallgirl]

Yeah, really bad idea

Ignoring the fact that the NEC says this isn’t allowed (unless the voltage is less than 30VDC ...), it’s just a bad idea. A large part of the problem is that you’re either on the “battery” side of a system with batteries, or you’re on the photovoltaic side. If you’re on the “battery” side, you won’t have enough current at less than 30 volts to be useful. If you’re on the PV side you have to derate by something like 156%, which makes matters even worse.

Anyway, DO NOT DO THIS. It’s just plain pointless.

Obviously, once you’re on the AC output side, Romex is fine so long as Code permits.

[Zee]

So I read all the posts and if I read them correctly, the only approved flexible cable assembly for DC PV run is type MC?

yes MC for cable assembly.

flex conduit is also an option but it of course has no wires

[Zee]

Good info, this first job I’m doing is on my own home and getting a raceway from the array would be an absolute nightmare with windows doors and eaves in the way there is no elegant way to make a run however with a new roof penetration, I can easily intersect the path that my #4 is taking from the new panel to the water service.

For anyone wanting to run Romex or where conduit is difficult or ugly: I recommend a micro-inverter system.
No DC. All AC. You can run all the Romex you want.

E.g. new construction: rough-in romex in walls if home-owner wants no conduit visible.

[Zee]

Good info, this first job I’m doing is on my own home and getting a raceway from the array would be an absolute nightmare with windows doors and eaves in the way there is no elegant way to make a run however with a new roof penetration, I can easily intersect the path that my #4 is taking from the new panel to the water service.

Depending on specific eaves windows etc......Consider running down other side of house and across crawlspace....., sometimes an option....., sometimes too much work.

[five.five-six]

Depending on specific eaves windows etc......Consider running down other side of house and across crawlspace....., sometimes an option....., sometimes too much work.

This first one is my house and there is just no easy way to do it. And the cold water entrance is on the other side of the house, living room with 24’ vaulted ceiling in between. It’s going to be a peach. The bright side though, the path runs right past my fishtank and I’m going to drop off 2 X 20 amp circuits for the tank while I’m running the DC and cold water ground.

[jaggedben]

This first one is my house and there is just no easy way to do it. And the cold water entrance is on the other side of the house, living room with 24’ vaulted ceiling in between. It’s going to be a peach. The bright side though, the path runs right past my fishtank and I’m going to drop off 2 X 20 amp circuits for the tank while I’m running the DC and cold water ground.

Remember you're not allowed to run PV DC with other circuits. Optimizer outputs are a grey area.

[five.five-six]

Remember you're not allowed to run PV DC with other circuits. Optimizer outputs are a grey area.

I mean, If I’m running the PV DC in type MC, do I need to drill their own hole in the studs?

I should probably contact the AHJ.

[jaggedben]

I mean, If I’m running the PV DC in type MC, do I need to drill their own hole in the studs?

I should probably contact the AHJ.

It's fine as long as you are in a different cable. The way you described it made me think you were perhaps planning to use a single conduit and pull multiple circuits.

[tallgirl]

For anyone wanting to run Romex or where conduit is difficult or ugly: I recommend a micro-inverter system.
No DC. All AC. You can run all the Romex you want.

E.g. new construction: rough-in romex in walls if home-owner wants no conduit visible.

You still can’t, unless you mean after you penetrate the roof.

As for new construction, run pipe, not wires. I will never again build a house with non-permanent (read: the usual electric stuff that’s not changing until we have Mr. Fusion in the kitchen) wiring in the walls. I had a client 8 or 10 years ago who ran pipe all over the damned place and it was SO much nicer when he had solar put in than hoping the right sized wires went to all the right places for all the things he wanted.

[ggunn]

You still can’t, unless you mean after you penetrate the roof.

You can't run Romex outside, of course, but you can run microinverter output circuits in Romex inside the building envelope. We do it all the time in many jurisdictions in Texas and have never failed an inspection because of it.

Where've you been? It's been years.

[tallgirl]

You can't run Romex outside, of course, but you can run microinverter output circuits in Romex inside the building envelope. We do it all the time in many jurisdictions in Texas and have never failed an inspection because of it.

Where've you been? It's been years.

You're not going to fail an inspection ... after you've penetrated the roof ... but solar, wired network cabling, and "home audio" are three things I think belong in pipe. NM is definitely cheaper and easier, but pipe is SO much easier to change your mind about.

Let's see. I was working for a large solar company which imploded, after I was working for a solar manufacturer which got acquired, after I went almost broke trying to run my own solar company, and then I swore off solar. I forget which one of those things was when I stopped posting here. I also forget how many cool things I invented that are making electric grids work better there were since then. Okay, I don't know if any of them are being used, but I padded the crap out of my patent portfolio with things somewhere along the line.

After bouncing around companies which have nothing to do with "electrical" I wound up at a company which makes things that control things that run on electricity.

[five.five-six]

solar, wired network cabling, and "home audio" are three things I think belong in pipe.

For C7 stuff, just use interduct. It’s a lot cheeper to run.

[tallgirl]

For C7 stuff, just use interduct. It’s a lot cheeper to run.

That would also work. Mostly I mean that technology changes and replacing wiring which has been stapled to the insides of walls is a pain in the ass to replace.

Solar projects last for decades -- there was one European research company I worked with about 5 years back which had arrays that were over 30 years old. There's been a lot of change in power conversion in the past 30 years.

[jaggedben]

You're not going to fail an inspection ... after you've penetrated the roof ... but solar, wired network cabling, and "home audio" are three things I think belong in pipe. NM is definitely cheaper and easier, but pipe is SO much easier to change your mind about.

....

If we're talking about this sort of thing ... (thread drift)...

Run all the loads in the house through a large gutter or j-box adjacent to the MSP. Then when I come to install a battery system with a backup loads panel, I can install a the backup panel off the gutter and easily and cleanly switch over the loads to be backed up. And then the customer can change their mind about it too, and I can come back (for more money) and change them all again.