Battery wire? Welding wire? when is 4/0 not 4/0?

biggerhammerbiggerhammer Registered Users Posts: 10
I'm planning a 4000 watt off-grid solar system. 18 panels, two banks of eight L-16s each, two Midnight Classic 150s.

Battery cables will be 2/0 to interconnect, 4/0 to the inverter.

In my wanderings through Google, I have found that:
  • copper wire is bloody expensive
  • Some kinds (such as THHN) are only very expensive, while
  • others such as battery cable are breathtakingly expensive

So, what kind of wire should I be using? Is welding wire OK? Does anyone know of a source that will hurt me less than the top twenty results on Google?

Thank you.

Comments

  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    I'm planning a 4000 watt off-grid solar system. 18 panels, two banks of eight L-16s each, two Midnight Classic 150s.

    Battery cables will be 2/0 to interconnect, 4/0 to the inverter.

    In my wanderings through Google, I have found that:
    • copper wire is bloody expensive
    • Some kinds (such as THHN) are only very expensive, while
    • others such as battery cable are breathtakingly expensive

    So, what kind of wire should I be using? Is welding wire OK? Does anyone know of a source that will hurt me less than the top twenty results on Google?

    Thank you.
    Battery cable, welding wire and diesel locomotive wire are very flexible designs which use finer than standard stranding to achieve that.
    These wire types need different lugs and terminal designs to work properly with that stranding.
    And not all of those wire types are accepted under the NEC for building wiring.
    SMA SB 3000, old BP panels.
  • hemmjohemmjo Solar Expert Posts: 90 ✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    I have found the best prices on welding cable at https://weldingsupply.com/
    I get terminal ends and shrink tube at http://www.elecdirect.com/ Keep checking here, they often have roll ends that sell at a good price. Right now they have some #1, 1/0, and 2/0.

    Also, when you google, search for welding cable, not welding wire. Welding wire is the consumable that melts to form the weld. Cable is what brings power to the electrode.

    I learned the hard way.

    Good Luck,

    John
    Two systems in the Dominican Republic  http://villagemountainmission.org/
    installed Feb 2014 at 19.796189° -70.893594°, Classic 150 + WBJR, KISAE SW1210, MN Battery Monitor, IOTA DLS 55/IQ4,  4- Solar World 275w, 4-6v x 225ah Trace Batteries
    installed Feb 2015 at 19.795733° -70.893372°, same components  as above
    Honda PowerMate PC0497000, 7000/8750w generator - powers the well and chargers maybe once a week






  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    THHN, is not UV resistant, so it is not appropriate for all locations. It is also very stiff.
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    You cant use welding cable as fixed wiring. Electrical code forbids it, because some one has already done it and burned their house down.
    THHN, is not UV resistant, so it is not appropriate for all locations. It is also very stiff.

    You will need some kind of UV resistant feeder wire for out side use.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • PhotowhitPhotowhit Solar Expert Posts: 5,658 ✭✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    oil pan 4 wrote: »
    You cant use welding cable as fixed wiring. Electrical code forbids it, because some one has already done it and burned their house down. You will need some kind of UV resistant feeder wire for out side use.

    This makes welding wire sound dangerous, and I don't doubt, improperly used, someone might well have "burned their house down"...

    ...but code compliant, finely stranded wire was unavailable until recently so most battery based installs before the last 10 years are likely done with welding wire! I've yet to meet someone who has had a problem. People will argue about weather or not to solder the wire (after crimping!)

    I'd have no fear using it, and actually will, I have some 4/0 set aside for when I change out my inverter for a large one. I think my 2/0 which came from a military vehicle inverter, isn't marked and likely welding wire.

    I doubt the DC side will be inspected closely, if you need to worry about code compliance, as I've noted before, most installs aren't done 'to code'. The very wires coming out of the back of a solar panel would require a ground mounted system to have a fence built around it for limited access for voltages above 30 volts.

    It's sunlight that breaks down the wire covering, I have a tiny bit of exposed wiring, under my solar array, that might get a couple minutes of direct sunlight a day during some times of the year. It spans the short gap between the power center and the battery box. I'll likely add some 3-4" conduit when I change out the inverter, but for now I'm living with what I have I likely have 20 years before needing to check to see if the wire casing is still pliable...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    I also use welding wire from my battery to the inverters. I had tought that battery cables had to be in conduit also or in a dedicated locked space. I do not have either. I found trying to put it in conduit not easy enough to mess with and the battery is in my garage with everything else I own.. I didn't have to get inspected and have no advice for anyone who does, although I did try (within common sense) to make it work and be safe.

    I do have one word of advice that you may already know, the cables from the battery need to be run together either twisted or just touching close together. I am told this helps your electronics.
    gww
  • biggerhammerbiggerhammer Registered Users Posts: 10
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    THHN, is not UV resistant, so it is not appropriate for all locations. It is also very stiff.
    Is THHN appropriate for interconnect and battery-inverter connections?
  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    Good question and I don't know for certain.

    I do know that my local inspector will not pass THHN for anything outdoors w/o it being in conduit. OTOH, my local inspector will pass standard welding cables used for battery interconnects and for the battery to inverter connection. He passed mine in 2009. The inspector does have the final word. Mine did check to see if the terminal ends were proper for the fine strand wire though. He also did pass the THHN where it exits the conduit from the underground run from the PV. There is about 2 feet not in conduit leading to the charge controller. That is in a locked ventilated but w/o direct sunlight cabinet same as the batteries and the inverter.
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • Organic FarmerOrganic Farmer Solar Expert Posts: 128 ✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    Two electricians were recently telling me about a product: 'NO-OX-ID' it is an electrical contact lubricant, that they are saying 2 gauge wire should be coated with before it goes into any splice or clamp terminal.

    It is like powdered aluminum suspended in a conductive grease, so the cable-to-terminal contact is 'better' and air can not get in to form oxides later on.

    Is anyone here familiar with this kind of product?

  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    Photowhit wrote: »
    ]
    ...but code compliant, finely stranded wire was unavailable until recently so most battery based installs before the last 10 years are likely done with welding wire!

    I'd have no fear using it, and actually will, I have some 4/0 set aside for when I change out my inverter for a large one. I think my 2/0 which came from a military vehicle inverter, isn't marked and likely welding wire....

    Battery being wired together is not fixed wiring, at that point it would be considered equipment. Just as the leads on a welding machine.
    NEC does not care at all about the wiring inside a vehicle.
    If its behind/in a wall or in conduit, it fixed wiring.
    Photowhit wrote: »
    ]
    I doubt the DC side will be inspected closely, if you need to worry about code compliance, as I've noted before, most installs aren't done 'to code'. The very wires coming out of the back of a solar panel would require a ground mounted system to have a fence built around it for limited access for voltages above 30 volts.

    There was almost no NEC code for solar, small wind power setups and fuel cell installs before 2014.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    Two electricians were recently telling me about a product: 'NO-OX-ID' it is an electrical contact lubricant, that they are saying 2 gauge wire should be coated with before it goes into any splice or clamp terminal.

    It is like powdered aluminum suspended in a conductive grease, so the cable-to-terminal contact is 'better' and air can not get in to form oxides later on.

    Is anyone here familiar with this kind of product?


    This has to be used on aluminum wire. I have not seen it put on old work where 100% copper wire is used. And when I say "old work" its stuff that has been built and torn out with in the last 2 to 5 years.
    Proper procedure to use it on aluminum is you wire brush the aluminum then apply goop.
    The goop is called anti-oxidant compound and I don't think putting it on copper would hurt.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    Is THHN appropriate for interconnect and battery-inverter connections?

    Extremely.
    On equipment (stuff that isn't fixed wiring) I use THHN and THWN all the time.
    For some builds I like the way the course stranded stuff holds its shape kind of like conduit.
    When you bend it up good, say use 4 gauge and a pipe bender and it looks real slick.
    Other times I need really flexible wire and use welding cable.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • Organic FarmerOrganic Farmer Solar Expert Posts: 128 ✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    oil pan 4 wrote: »
    This has to be used on aluminum wire. I have not seen it put on old work where 100% copper wire is used. And when I say "old work" its stuff that has been built and torn out with in the last 2 to 5 years.
    Proper procedure to use it on aluminum is you wire brush the aluminum then apply goop.
    The goop is called anti-oxidant compound and I don't think putting it on copper would hurt.

    I assume that there is some copper variant of this stuff to be used for copper cable.
  • PhotowhitPhotowhit Solar Expert Posts: 5,658 ✭✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    oil pan 4 wrote: »
    Battery being wired together is not fixed wiring, at that point it would be considered equipment. ...
    If its behind a wall, it fixed wiring.

    That's interesting,...
    oil pan 4 wrote: »
    There was almost no NEC code for solar, small wind power setups and fuel cell installs before 2014.

    That's wrong! Things keep changing, but it was a big deal back in 1990's, when even Robin Gudgel admitted while working on inverters for Trace Engineering (later Xantrex, now Schnieder) "I never made the U series able to accept battery cable conduit because I had little knowledge of the NEC." The quote is from an article about Robin's history in Solar, since he has been responsible for much of the available code compliant equipment it might be a good read.

    Here is a UNM article about the Solar referenced in NEC specifically referencing Photovoltaics in 1984. Heck our Bill wrote NEC about dangerous code in the 2010(?) revision.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    A lot of solar code has been added or changed last year. Most of it appears to be added. I do not have a 2011 book. I think it got tossed when the boss picked up the 2014 book. There has been something in there for solar panels for quite some time but last year it all got a lot more specific.
    If I ignore the highlighted section of the text (most of the high lighted appears to have been added) it looks pretty basic.

    The copper and aluminum goop appears to be silicone grease.
    At least that's what you find inside the copper to aluminum splice lugs.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • mike95490mike95490 Solar Expert Posts: 9,363 ✭✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    I don't know where the code cops are on this, but I'll raise the alarm for the following.

    Welding Cable. it's flexible, and if you don't use the RIGHT lugs made for fine strand wire, it works it way out of the lug and the connection goes bad. And the large lugs need to be hydraulically crimped. A hammer/anvil crusher will not crimp them properly. Welding cable is NOT certified for fixed install wiring.

    "No-Ox" aluminum wire goop. Required for any connection with aluminum wire. It's a abrasive grit in a grease, to insure good contact to the aluminum wire. aluminum oxidizes nearly instantly upon contact with atmospheric oxygen, and that oxide has to be abraded off, and prevented from forming again. it's not just grease. Avoid the flammable brands.
    There is silver and copper cable grease for copper wires, but it's use is optional. The grease is conductive, filled with metal dust, and if overused, will drip, sag, run and cause a short.

    Good cables are expensive. There is no substitute. Not all inverters will accept 4/O cable, so make sure before you buy. use a solar wire caculator to select the right size cable for your voltage, amperage and length.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    Mike
    Welding Cable. it's flexible, and if you don't use the RIGHT lugs made for fine strand wire, it works it way out of the lug and the connection goes bad. And the large lugs need to be hydraulically crimped. A hammer/anvil crusher will not crimp them properly. Welding cable is NOT certified for fixed install wiring.

    "No-Ox" aluminum wire goop. Required for any connection with aluminum wire. It's a abrasive grit in a grease, to insure good contact to the aluminum wire. aluminum oxidizes nearly instantly upon contact with atmospheric oxygen, and that oxide has to be abraded off, and prevented from forming again. it's not just grease. Avoid the flammable brands.
    There is silver and copper cable grease for copper wires, but it's use is optional. The grease is conductive, filled with metal dust, and if overused, will drip, sag, run and cause a short.

    I am not saying you are wrong, I am saying that after reading your post I have my fingers crossed. I used 4/0 welding wire, the crimp rings that naws sells, a hammer crimp and double wall glued shrink wrap. I put oxygaurd on all connections (copper and alum) prior to any crimping and at all connections including my battery buss bar, IE: two stainless bolts. I beat the crap out of the crimps and all seemed well. I will tell you in twenty years how bad it went and as I said I will have my fingers crossed. So far so good.
    Thanks
    gww
  • PhotowhitPhotowhit Solar Expert Posts: 5,658 ✭✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    GWW, I used a hammer crimper on my 2/0 with out an issue, if in the future someone is unsure and wants to make lug ends, you can effect the same type of bond of a hydraulic crimper by putting the hammer crimper in a table vise. Or find a shop that uses a hydraulic crimper to make welding cables...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • hemmjohemmjo Solar Expert Posts: 90 ✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    I used #4 and #2, welding cable for the installation I did. It is not inspected in mountains of the Dominican Republic, but I still do not want to burn the building down!!!

    I used a hammer crimper, then used a torch to slowly heat the tip of the lug and added high sliver content electrical solder to the lug. Use caution that you do not get it so hot as to melt the cable jacket. I highly recommend PRE-BENDING, any short cables you make BEFORE you crimp the lug. Does not have to be perfect, just close. As soon as you crimp the lug onto that soft flexible cable, it will become stiff as the little wires can no longer slide past each other. After you add solder it is even stiffer. This is a testament to how much movement there is between the wires even after the lug is crimped.

    Good Luck,

    John

    PS; I have found that http://www.elecdirect.com/ has the best prices on cable lugs. And they have been very helpful with questions.
    Two systems in the Dominican Republic  http://villagemountainmission.org/
    installed Feb 2014 at 19.796189° -70.893594°, Classic 150 + WBJR, KISAE SW1210, MN Battery Monitor, IOTA DLS 55/IQ4,  4- Solar World 275w, 4-6v x 225ah Trace Batteries
    installed Feb 2015 at 19.795733° -70.893372°, same components  as above
    Honda PowerMate PC0497000, 7000/8750w generator - powers the well and chargers maybe once a week






  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    gww1 wrote: »
    Mike


    I am not saying you are wrong, I am saying that after reading your post I have my fingers crossed. I used 4/0 welding wire, the crimp rings that naws sells, a hammer crimp and double wall glued shrink wrap. I put oxygaurd on all connections (copper and alum) prior to any crimping and at all connections including my battery buss bar, IE: two stainless bolts. I beat the crap out of the crimps and all seemed well. I will tell you in twenty years how bad it went and as I said I will have my fingers crossed. So far so good.
    Thanks
    gww

    Wow, I must be getting old (and yes, the music is too loud now), but I just don't see the benefit to doing this instead of using the approved wire.

    I'm not sure of the length, but I found Storm Copper Components, http://www.electrical-insulators-and-copper-ground-bars.com/solar-batter-interconnect-cables-40.html

    selling the NEC approved cables. For a 10' kit of one red and one black, they want $126 (with FREE UPS shipping no less!), and just for the record I'm not affiliated with them in any way, and we don't want this to turn into a blatant advertising thread, but I did buy my solar battery components from them. And I thought that in the past NAWS sold NEC approved cables, but maybe they'll either bring them back or add them to the catalog.

    Now, will everything be OK with the welding wire? The odds are excellent. But, if something goes wrong, maybe even with some other component, there is a disaster, and the fire marshal makes an incorrect determination that the non-NEC wire played at least some part, there's major problems. And it sounds, based on what Mike95490 said, that it is a slow insidious process of strands deteriorating, and over time this gets to be a cascading problem.

    So I just don't see that buying the incorrect welding wire, the crimp rings, either the equipment to put them on or paying somebody to do it, is it really saving anything initially? Now maybe if you're a welder by trade and have the wire and other components and tools, you'd be saving, but I'd think that a welder would also want to do critical components correctly.
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    Sub

    I don't dissagree nessisarily with what you say, Its just that while doing my homework it seemed everyone has been doing this since moby dick was a minnow. I knew when I bought a forktruck battery that its leads would be welding cable.

    I bought an extra 15' when I bought the battery. Now because of that, I might be compounding a bit bad to being even worse but it did have a proven track record as I weigh it.

    It is like buying insurance. My house got robbed once and I had the basic insurance plan and so only got $2500 bucks on jewlery when I had lost about $ 6000 bucks worth. I have a seven year old car and if I knew I was going to wreck it tommorrow I would keep full coverage but I am going to take a chance and just get libility.

    I felt the track record on welding wire was ok and realized also it is not nec rated for a reason.

    I found geathering everything to put a solar system together very time consuming and didn't want to shirk on doing it well but also wanted to get done at some piont. The battery coming with that cable seemed a step in the right direction. It was also less then half the cost of what you listed.

    It fit my risk level threshold but like life insurance, everybody has to decide how much is right for them.

    I am not promoting the use of non nec stuff for others and am still learning myself, sometimes at a cost. I just say what I have did and am happy with so far. I do know that battery acid and corrotion can ruin any wire and getting the end sealed with srink wrap seemed like a good ideal.

    Again, I am not really promoting some one else do what I did. I know where I live and what will pass as average here and examples to use in my defence if something goes wrong and a finger is pointed at something that had nothing to do with the thing that went wrong.

    I am glade to have things together and working as instulation is a duanting but do-able project that is nice when done.
    Cheers
    gww
  • PhotowhitPhotowhit Solar Expert Posts: 5,658 ✭✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    Well, You do understand that you can buy UL listed products that NEC does NOT approve for home use?

    Storm Copper Components apparently doesn't they don't tell you what wire they are using or what use it's UL approved for, if it is.

    FWIW- UL approved flexible wire wasn't available until the last 10-15 years, I work for a while at a battery supply shop that made cables with a mechanical crimp tool, They used welding wire and often made thicker cable for car starters for high performance cars, with 2/0 - 4/0 cable. They hadn't seen a failure.

    I won't worry, and certainly wouldn't buy from a place that's not telling you what you're getting.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • BB.BB. Super Moderators, Administrators Posts: 32,026 admin
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    Some information about UL Listed stuff is in the UL file, but is company secret and UL will not give you all the data needed.

    I had to make the design and submit to UL, they looked behind the curtain and told me yes or no.

    Gets weird sometimes.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • hemmjohemmjo Solar Expert Posts: 90 ✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    This is getting interesting. What is the correct specification for cables used to wire the high amp DC side of a system?

    Thanks,

    John
    Two systems in the Dominican Republic  http://villagemountainmission.org/
    installed Feb 2014 at 19.796189° -70.893594°, Classic 150 + WBJR, KISAE SW1210, MN Battery Monitor, IOTA DLS 55/IQ4,  4- Solar World 275w, 4-6v x 225ah Trace Batteries
    installed Feb 2015 at 19.795733° -70.893372°, same components  as above
    Honda PowerMate PC0497000, 7000/8750w generator - powers the well and chargers maybe once a week






  • BB.BB. Super Moderators, Administrators Posts: 32,026 admin
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?

    From our host:

    http://www.solar-electric.com/installation-parts-and-equipment/wiring-cables-and-connectors/hardware-wire/bainca.html
    Note: We are currently transitioning from using welding cable to using MTW UL listed cable for all of our battery/inverter wiring. Many solar companies sell welding cable for use with batteries and inverters. There's no safety issue when using welding cable, but it can cause problems with some electrical inspectors. Technically, welding cable is only meant to be used on welding machines. When welding cable is used on anything but welders, it violates the national electric code (NEC). This is why we've started using MTW listed cables. MTW stands for "Machine Tool Wire" and it's essentially the same thing as welding cable, but with a more versatile electrical listing. This means it's approved for many more uses than standard welding cable. If you would like to learn more about cable and wire listing and use, please read this article entitled "Clarifying Confusing Cables" from Home Power Magazine. All other cables are welding cable, unless otherwise specified.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • 2manytoyz2manytoyz Solar Expert Posts: 373 ✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    BB. wrote: »

    Thanks Bill. I'll keep that in mind when ordering wire in the future. In the meantime, the welding cable is VERY nice to work with. None of mine is exposed to sunlight. I also have installed a Blue Sea #5191 fuse block on each battery terminal to protect the wiring.

    Using 4/0 cable between the bus bars and the inverter:

    dscn7124.jpg

    And 2 gauge wire between the 8 batteries and the bus bars.

    battcables.jpg
  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    , but I'd think that a welder would also want to do critical components correctly.

    Nope I have taken welding machines apart and you would be surprised how cheaply made they can be.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    oil pan 4 wrote: »
    Nope I have taken welding machines apart and you would be surprised how cheaply made they can be.

    Yeah, I took a dead mig welder apart a few months ago and I was surprised to find that the entire transformer was wound with Aluminum wire!
    And it wasn't one of those cheap harbor freight ones either, it was a brand name (can't remember the name).
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • oil pan 4oil pan 4 Solar Expert Posts: 766 ✭✭✭✭
    Re: Battery wire? Welding wire? when is 4/0 not 4/0?
    jcheil wrote: »
    Yeah, I took a dead mig welder apart a few months ago and I was surprised to find that the entire transformer was wound with Aluminum wire!
    And it wasn't one of those cheap harbor freight ones either, it was a brand name (can't remember the name).

    You will be hard pressed to find a big name welding machine made by the big 3 that has an actual copper inductor and transformer.
    My heavily modified stick welder has a copper inductors, because I poached them out of some military surplus junk at the scrap yard.

    I have seen welders that have wire nuts connecting the out put leads to the machine. 14 gauge inlet power cord that handles 30 amps. 12 gauge power inlet cord that handles up to 55 amps, 6 gauge welding leads that handle 225 amps, 10 gauge leads that handle 100 amps. A tiny toggle switch that was handling 30 amps.

    I think you might be able to buy UL stickers off amazon or ebay and stick them on anything.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

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