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  • Off-Grid Wiring Tips

    OK this does not apply Grid Tied System, just battery systems. To make life easier and safer for you here are a few wiring tips. Use Marine wire and cable. Marine wire and cable comes in 3 basic types.[LIST][*]Battery; 4 AWG to 4/0 AWG single conductor[*]Primary; 18 AWG to 6 AWG single conductor[*]Duplex/Triplex; 18 AWG to 6 AWG with 2 or 3 conductors in a common sheath.[/LIST]
    Marine cable is a bit different than power and lighting wire used in a building. Short version it is superior in every way. Main points are: [LIST=1][*]Cable insulation for wire made for home wiring has a temperature rating of of 60, 75, and 90 degree Celsius. Marine is 90 degree which means is can handle more current and heat although with voltage drop limitations you really cannot take advantage of that except on short runs. Example 12 AWG THHN, RHH etc is limited to 20 amps, Marine is 25 amps as an example.[*]Marine cable insulation is rated for High Temperature, Wet/Damp, Salt, Corrosive, Oil, and Gas environments.[*]Marine cable insulation is much easier to work with because it uses synthetic rubber vs thermoset plastic and rubber. God forbid if there is a fire, Marine cable produces less smoke, less corrosive gasses, and self extinguishes when the heat source is removed.[*]Wires are tinned copper. This makes the wire more resistant to corrosion from salt air, acid battery gasses, and fuel vapors.[*]Marine wire uses flexible stranding types aka finer strands (Class H). This makes it much easier to work with and the big benefit is less prone to wire fatigue from movement and vibration. Take note RV users, it is easier to route through tight bends, and resist breaking off from constant movement and vibration.[/LIST]
    There are two downsides to using Marine wire and cable. It is a bit more expensive, and extra care is needed to terminate it properly due to the finer wire stranding. The best way and tip I can give you is most of you do not have the skill or tools to terminate any wire properly. Not meant as an insult, but the tooling is expensive and unless you are in the biz cannot afford a thousand dollar tool to terminate cable for a one-time job. Having said that unless you order the cable online, most any RV or Marine shop has the tooling to terminate the cables. Even many Marine Online suppliers like Blue Sea will terminate cable for you to your specifications. Other sources are Golf Cart shops, Ham Radio Outlet, Grainger, and electrical contractors.

    I save the best tip for last and maybe the most important, that is the use of a Anti-Oxidant compounds on both the Wire Skinners and Contact Mating Surfaces. The Wire Skinner is the portion of the wire you strip the insulation from. You want to use a very lite coat of a Anti-Oxidant. Apply it to both Wire Skinners and Mating surfaces and make sure you apply ample torque whit appropriate locking hardware. If you have the option use two-hole terminals vs single-hole terminals. As for the Anti-Oxidant the best just happens to be one of the least expensive and the only brand utilities allow to be used made by San Chem called "[B][I][U]NO-OX-ID A SPECIAL[/U][/I][/B]". Use not other. All it takes is a very lite coat and be sure to coat all exposed surfaces. Once applied you will never have a corrosion problem. Utilities have 50 year old installation in salt air and never have had a problem. It is [B][I][U]cheap and a small tube[/U][/I][/B] will last you a lifetime. Works on copper, aluminum or any metals or dissimilar metals. Model Electric Train and electric slot car folks take note, apply a light coat on the track and you will never have another problem. Buff connections lightly with Green Scotch-Brite to make shiny, and apply a light thin coat. Be sure to coat all exposed surfaces of the Battery Term Post and terminals. [U]Use lead plated terminals without inspection hole on Battery Term Post. [/U]


    Last edited by Sunking; 05-12-2018, 02:22 PM.
    MSEE, PE

  • #2
    Would this be OK to use in a telecom 48V system? Reason I ask is because we've been using welding cable in some 48V systems and recently I inferred from the NEC that it needed to be dual-listed for that application. I think you and I talked about that and you mentioned locomotive cable as a good substitute. Would the Marine cable be good for that too or are you suggesting it more for RV type applications?

    Comment


    • #3
      Yes if no inspection is required. Welding cable is OK if listed RHH/RHW. Typically DLO and RHH is the dual listed welding cable.

      Now for a more detailed answer. You already know about Dual Rated cables and alphabet soup when it comes to cable insulation types. Here is the deal, a cable manufacture to have a listed cable must have it tested by UL and they have to pay for it. Want dual listed? You pay twice. Marine UL cables exceeds most NEC applications. Equivalent NEC is going to be RHH/RHW and MTW. FWIW MTW and Marine cable are identical.

      However allow me to point you in a different direction. Look for KS24194 Power Wire. Several manufactures make it. It carries a RHH/RHW UL listing. It comes in Class I and Class B stranding, is Low Smoke, Non Halogenated and some comes with the Cotton Sheath so it can be laced to cable racks without Fish Paper. There are several Manufactures that make it, most notable is Cobra and GE. Anixter and Southwire are good sources. Pretty much default choice for all Telco power wire. Can be used anywhere in NEC applications with RHH/RHW 600 -Volt rating. It was developed a few decades ago from a [B][I][U]Central Office Fire in Chicago Hinsdale[/U][/I][/B] office on Mothers Day May 8, 1988 that wiped out most of Chicago's telephone traffic for a month. The fire did not destroy any equipment or even destroyed a single room. All the damage was for acidic smoke and the water used to extinguish the fire. Water and Cable insulation made with sulfur made sulfuric acid and ate the electronics in all the switch and transport equipment. Bellcore made a standard called KS24194 that all power cable be Low Smoke Non-Halogenated (no sulfur compounds) cable. Marine industry had already been using it. Go figure Paul Harvey. .

      [B][I][U]KS24194[/U][/I][/B]

      Last edited by Sunking; 05-13-2018, 03:50 PM.
      MSEE, PE

      Comment


      • #4
        Hello,
        I'm new to this forum and I have no ideea where to ask this:
        I'm thinking of going offgrid with a 48v setup. 24x2V/800Ah battery bank and 5kw inverter for running the house appliances.
        For the lights I was thinking to go with a separate 12V/200Ah battery. Basicly 2 seaparate systems. 1 or 2x250W mono for lights and 12x250W mono for the 48v system.
        Is this a good ideea?
        My location is in Romania (Europe).
        Winter time lasts for about 4 months with 3 to 5h of sun.
        Thanks

        Comment


        • #5
          Originally posted by Joseph81 View Post
          Hello,
          I'm new to this forum and I have no ideea where to ask this:
          I'm thinking of going offgrid with a 48v setup. 24x2V/800Ah battery bank and 5kw inverter for running the house appliances.
          For the lights I was thinking to go with a separate 12V/200Ah battery. Basicly 2 seaparate systems. 1 or 2x250W mono for lights and 12x250W mono for the 48v system.
          Is this a good ideea?
          My location is in Romania (Europe).
          Winter time lasts for about 4 months with 3 to 5h of sun.
          Thanks
          NO. You are going to have the 48V 5kw inverter on all the time anyway, right ? Build and wire the house just like normal and there will be no surprises, no special bulbs to buy, no mistakes .
          Get a good reliable inverter, something in the XW+ or the XW line. Buy good gear, and it will last, buy cheap stuff, and you keep buying when it breaks, and when it breaks something else. And you only have one set of batteries to maintain. Don't forget, you will be using a backup generator in winter, or you destroy your batteries.
          https://solar.schneider-electric.com...brid-inverter/ 5.5kw or 6.8kw sizes
          https://solar.schneider-electric.com...-xw-230v-50hz/
          Powerfab top of pole PV mount (2) | 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

          Comment


          • #6
            Thanks for your answer Mike. I've uploaded the battery datasheet. Can you have a look at it and tell me if it's a good option? It's about 600$/ element
            Attached Files

            Comment


            • #7
              Poor battery for solar, in my opinion.

              a) No warranty period listed. They only speak of 20yr Float life.
              b) 6000 cycles = 16 years @ 20 % discharge. I can't seriously believe that
              c) sealed battery = expensive, no recovery if you have a charging mistake and vent gas.
              * Do you really need sealed batteries. It's been my understanding they don't last as long as flooded
              * Have you lived off grid with batteries before? Its common for a first time mistake to ruin your first bank. Expensive learning.
              d) Where will the batteries be located ? in house? basement? outbuilding?
              Powerfab top of pole PV mount (2) | 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

              Comment


              • #8
                Warranty period is 48 months, listed on the suppliers site
                I don't need sealed. For now I'm reaserching only. I plan to build the system in about 2 years from now.
                I lived offgrid only short periods of time (1 week at most) at a remote cabin.
                Can you point me to some good flooded batteries? Even if the supplier is in U.S.
                Thanks

                Comment


                • #9
                  I always suggest golf cart batteries (either 6 or 8 volt styles) as they are cheap and affordable to make mistakes on. Every country has them.
                  Next step up is the Floor Scrubber batteries ( L-16 size ) These are also deep cycle. avaiable at better battery stores everywhere there are floors to be scrubbed
                  ( grocery store isles at night, big box warehouse stores....... )

                  then you get to the $olar batteries, where they change the sticker and jack up the price !!
                  Powerfab top of pole PV mount (2) | 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

                  Comment


                  • #10
                    Mike, from your experience, how many kw should be the pv array size for a 48v 800ah battery. Some pv calculators give me some 3.6kw minimum array size.
                    Thanks

                    Comment


                    • #11
                      Originally posted by Joseph81 View Post
                      Mike, from your experience, how many kw should be the pv array size for a 48v 800ah battery. Some pv calculators give me some 3.6kw minimum array size.
                      Thanks
                      I am sure Mike will give you an answer but for now I will say you will need about 80 amps of charging from your pv array. 80a x 48v = 3840watts. The amount of watts can be reduce to 3200 which might get you a C/12 charge rate from 67amps but with losses I would make sure I am closer to that 3800watt figure.

                      Comment


                      • #12
                        80A @ 48V = 3840 x 1.2 = [B]4608[/B]w suggested nameplate. Panels generally produce 80% of their nameplate at realistic ambient temperature.
                        Powerfab top of pole PV mount (2) | 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

                        Comment

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