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diy solar

Running ac through dc cables

J

Jonathan123

New Member
Joined
May 26, 2022
Messages
46
Location
Arlington, MA & Chesterville, ME
I’m moving panels and controller/inverter to a better spot with more sun that’s further from my water-side pump. To minimize voltage drop I’ll run power down to the pump in ac instead of dc. Have read mixed things about using dc cable to run ac current and am wondering what the consensus is here (if there is one.)

Existing dc cable is 10 awg rated for either 600 or 1,000 volts, can’t remember which. Pump uses 220v ac at 8 amps. Can I extend my cabling using the same stuff as above or do I need to dig up what I have and run new cable? My understanding is that voltage-wise I’m ok but there seems to be strong opinion about using stranded cable for dc and solid for ac.
 
There is no difference with cables ac or dc.

There is also no benefit to using ac or dc for long distance, unless the dc is low voltage, which would be high amperage.

You said panels, if the panel voltage is high, that is the best way to send watts. Via highest voltage.

Give us more background. What are you planning?
 
as long as you use a voltage drop calculator and its less than 2% then its a non issue. a bigger issue is poor connections. if in doubt look at up in smoke and see what happens to a large cable that is not properly tightened down. (my screw up). I had been running my system for a little over 5 years when while rearranging a few things i missed tightening down one cable... if you look at my post that is 2 gauge fine strand welding cable. capable of carry a metric buttload of volts and amps.. yet I smoked it by not tightening down stuff properly. it happens to the best of us.

so cabling and connections. proper torque, using an oxidation preventing paste... proper sanding and prep of connections. etc. etc.
 
Jonathan123 said:
but there seems to be strong opinion about using stranded cable for dc and solid for ac.
Click to expand...
The real issue is flexibility, and how important that is in the application. Almost all AC applications are in walls, where there is no motion whatsoever. So, cheaper to make solid core wire makes perfect sense, because there is little chance for it to receive any damage.

In situations where the cable is expected to be moving, that's the application where stranded wire becomes important. Stranded wire is far less susceptable to cracking, so that's why it's used in applications like AC extension cords, which are expected to laid out, and rolled back up more or less continuously.
 
MichaelK said:
where the cable is expected to be moving, that's the application where stranded wire becomes important
Click to expand...

Wow such a good explanation. Makes sense. Thank you for posting it. And OP is somewhat right. RV installations tend to have a lot of DC wiring.. in motion. So stranded that is.
In a house.. AC wiring.. no motion .. solid copper.
 
Jonathan123 said:
I’m moving panels and controller/inverter to a better spot with more sun that’s further from my water-side pump. To minimize voltage drop I’ll run power down to the pump in ac instead of dc. Have read mixed things about using dc cable to run ac current and am wondering what the consensus is here (if there is one.)

Existing dc cable is 10 awg rated for either 600 or 1,000 volts, can’t remember which. Pump uses 220v ac at 8 amps. Can I extend my cabling using the same stuff as above or do I need to dig up what I have and run new cable? My understanding is that voltage-wise I’m ok but there seems to be strong opinion about using stranded cable for dc and solid for ac.
Click to expand...
Voltage type is irrelevant.
Unless you are talking above 2000V or over 120hz ac or dc, solid or stranded makes no difference.
As stated, what DOES matter is conductor diameter, and if flexibility is needed to allow for vibration.
 
Weird question. Has anyone ever used 4/0 battery cable for a short AC feeder?

Asking because I lucked into a boatload of high quality 4/0 boat cable. Multiple UL and AYBC listings. 105 C and 600 v.

I have an install into boxes with very small gutters and tight bends. Lot easier to deal with 2100-strand boat cable than 4/0 copper THWN.

If there’s no problem doing this, does anyone have suggestions for a thin-wall ferrule for 4/0 small-stranded copper?
 
Last edited:
GuyG said:
Weird question. Has anyone ever used 4/0 battery cable for a short AC feeder?

Asking because I lucked into a boatload of high quality 4/0 boat cable. Multiple UL and AYBC listings. 105 C and 600 v.

I have an install into boxes with very small gutters and tight bends. Lot easier to deal with 2100-strand boat cable than 4/0 copper THWN.

If there’s no problem
Doing this, does anyone have suggestions for a thin-wall ferrule for 4/0 small-stranded copper?
Click to expand...
the power and the wire do not know nor care. the major difference is cost, and flexibility. why waste money on fine strand in a house where the bends are easy? why attempt to force THWN into small spaces on a truck, car, airplane or boat? the wire itself,and the electricity itself do not care. as far as the ferrules go you are on your own there, I would look at welding supply houses.
 
GuyG said:
Weird question. Has anyone ever used 4/0 battery cable for a short AC feeder?

Asking because I lucked into a boatload of high quality 4/0 boat cable. Multiple UL and AYBC listings. 105 C and 600 v.

I have an install into boxes with very small gutters and tight bends. Lot easier to deal with 2100-strand boat cable than 4/0 copper THWN.

If there’s no problem doing this, does anyone have suggestions for a thin-wall ferrule for 4/0 small-stranded copper?
Click to expand...
Fine stranded large gauge wire needs extra attention in getting a good and tight connection. Tighten, wiggle, tighten, wiggle, tighten, wiggle, tighten, wiggle, tighten, wiggle.. then F ing PULL!!! if it doesnt move you should be good. Oh, and recheck the tightness every 3 months.

Oh nevermind... You were looking for a ferule... :)
 
GuyG said:
Weird question. Has anyone ever used 4/0 battery cable for a short AC feeder?

Asking because I lucked into a boatload of high quality 4/0 boat cable. Multiple UL and AYBC listings. 105 C and 600 v.

I have an install into boxes with very small gutters and tight bends. Lot easier to deal with 2100-strand boat cable than 4/0 copper THWN.

If there’s no problem doing this, does anyone have suggestions for a thin-wall ferrule for 4/0 small-stranded copper?
Click to expand...
These are made for exactly this use.

NSi/Tork Sales | Polaris Grey Connectors - Replacement Sleeves

Polaris Grey comes with an integral sleeve which protects the fine strands and helps the conductor maintain its shape during the tightening process. The sleeve eliminates breakage of the strands and reduces stress on the conductor and therefore the potential for hot-spots.
nsi-sales.com
 
Daddy Tanuki said:
why waste money on fine strand in a house where the bends are easy?
Click to expand...
Maybe I wasn’t clear. I already have hundreds of feet of the 4/0 boat cable on a spool that was basically a gift, and I have no need for nearly that much. (Hmm, unless anyone here wants to buy some). And the bends on this project are very tight, into four very small, cramped enclosed breakers. Doable, but not “easy” at all. So I’m proposing to use the boat cable I already have instead of shelling out for new (and stiffer) THHN.

Because that’s unusual, I just wanted to run it by the forum to see if I’ve overlooked any reason not to. Yeah, I know that terminations and torquing need more attention; anything else?
 
GuyG said:
Maybe I wasn’t clear. I already have hundreds of feet of the 4/0 boat cable on a spool that was basically a gift, and I have no need for nearly that much. (Hmm, unless anyone here wants to buy some). And the bends on this project are very tight, into four very small, cramped enclosed breakers. Doable, but not “easy” at all. So I’m proposing to use the boat cable I already have instead of shelling out for new (and stiffer) THHN.

Because that’s unusual, I just wanted to run it by the forum to see if I’ve overlooked any reason not to. Yeah, I know that terminations and torquing need more attention; anything else?
Click to expand...
Wow.
100feet of 4/0 copper welding cable is worth around $800
Ya might wanna sell some extra here in the for sale forum.
 
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