2 AWG AC Cable?

[Mrgulabull]

I've just purchased a Victron Multiplus II 5000kva 48v 120v inverter to replace a failed Growatt. The Victron manual calls for 2 AWG on the AC output side. I'm quite comfortable and familiar with DC cabling, but am a bit lost when it comes to AC.

I've looked all over for a 3 conductor 2 AWG cable that I can use to handle the AC output but it seems this either isn't common or doesn't exist. If this sort of cable doesn't exist, would it make sense to create my own cable using spare 2 AWG welding wire I have laying around? I was thinking of using 3 of these cables for hot, neutral, ground, and placing them in metal conduit. Does this present a hazard of some sort?

Thanks for any feedback or guidance!

 

[pvgirl]

Norma, option would be THHN or other NEC approved wire in conduit. Unless you are using the full 90amps pass thru input you won't need to the full capacity of 2 awg on the output. What size breaker/service/input is on the inverter input?

 

[Mrgulabull]

Thanks for the reply.

I am off grid and will not supply anything on the AC input side, all power will come from batteries.

I was looking at page 18 of this PDF that describes maximum AC output amps of the 5kva model: https://www.victronenergy.com/uploa...ultiPlus-II___Quattro-II_120V-230V-pdf-en.pdf

It’s a little confusing how it’s worded, but based on what I’m reading and what you’ve said, perhaps I should only expect ~42 amps maximum? In which case 2 AWG would be way larger than necessary and I could just use 6 AWG (which is much easier to find as a premade 3 conductor cable).

 

[pvgirl]

With no AC input there is no issue using 6 AWG which will meet NEC requirements for 125% of max rated output(42amps), which is 53 amps and below the 55 amp rating of 6 AWG.

 

[RCinFLA]

#2 is way overkill for a 5kVA 120vac inverter. The only reason they are specifying such a large gauge is because the inverter has 100 amp pass-through relay so they are sizing the wire gauge for maximum pass-through current.

Unless you really need 100 amp ACin to ACout pass-through current I would not use #2 gauge.

If you put 60 amp breaker on AC input #6 is sufficient and meets electrical code.

 

[Mrgulabull]

Thanks for the detailed replies, RCinFLA and pvgirl! Just what I needed to know.

 

[Balrog006]

In which case 2 AWG would be way larger than necessary and I could just use 6 AWG (which is much easier to find as a premade 3 conductor cable).

Be aware that not all wire/cable is created equal and depending on its use, environment and installation method some wire is fine while others are not. Your ‘premade 3 conductor cable’ sounds like NM-B cable (Romex) which is fine for some interior, box to box applications, but not for anything in conduit, in a wet/damp location, in an exposed installation, outside, etc. cable in conduit must be rated for the conduit. Cable in conduit outside (considered a wet location) is different than inside, etc.

You have to select your cable/wiring for the situation, not just randomly or pick the easiest/cheapest one available or that you are familiar with.

 

[Hedges]

NM-B cable (Romex) which is fine for some interior, box to box applications, but not for anything in conduit, in a wet/damp location, in an exposed installation, outside, etc. cable in conduit must be rated for the conduit. Cable in conduit outside (considered a wet location) is different than inside, etc.

Romex with its plastic jacket is run through interior locations.
If it enters a box, has jacket removed, and is run through the box to where it connects to breakers, is that OK? (obviously yes.)
If it runs through the box, through a nipple or a 10' conduit into another box before connecting to something, is it not OK? (if not, why not?)
I do note that my spools of individual wires have a clear outer layer, protection while pulling in conduit, I think.
What I do with ends of Romex (jacket removed) would be less severe than when I pull through long conduit and bends.

I get that for conduit in wet location, the wire (insulation) would have to be rated for wet. Some insulation has different temperature rating wet vs. dry. I've also noticed that dry location cables such as Romex often have paper strands twisted with the wires, while wet location cables such UF do not.

Is all conduit outside considered wet location? Conduit underground we have to assume fills with water. Conduit run vertical from 3R boxes, which are rain proof on top and have drainage holes on bottom I would think not. A surface-mount exterior breaker panel, of course I run Romex to. But I've got multiple boxes connected together. Also planning to put a wiring channel in crawl space, connected by short conduit runs to boxes and switches outside. So ends of Romex in conduit (< 2') is useful, seems better than a bunch of splices in the wiring channel.