Wire Gauge Question

..Hi,

I have a question:

I have found some low gauge wire that I want to use for my system but it says its welding cable..its 1-4 gauge..is this the same as normal 1-4 gauge DC wire or is this something different.

Most of it says it is capable up to 600v..

Also, for my inverter it says to use a lower gauge wire for the ground..does this mean I need lower then 1 gauge when I use a 1 gauge wire for the positive? ( I don't think the gauge is lower then 1...)

thanks!

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Wire Gauge Question

    Wire is wire. It doesn't care if it's carrying AC or DC.
    The important thing to remember is to size it for the current it will be handling over the distance between connections. The larger gauge (lower number, mostly) the better. I've never heard of "1-4" AWG.
    Most of us use welding cable for the low voltage DC connections. It is usually rated as "00" or "2/0" or higher (up to 000 or 4/0).
    Grounding applications probably wouldn't require anything thicker than 6 gauge.
    I'm sure some of the experts on this board will be pleased to give you the excat why-fors! :D
  • System2
    System2 Posts: 6,290 admin
    Re: Wire Gauge Question

    ..just to clarify 1-4 means a gauge from 1-4 - my positive connection from the battery to the inverter is supposed to be 2, the negative is supposed to be 4.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,408 admin
    Re: Wire Gauge Question

    When you are distributing power, the + and - connections should be equal in size (gauge). It does not make much sense to have a 2 awg positive wire and a 4 awg wire on the negative... Same current needs to flow through both wires, so both need the same minimum gauge (if the minimum needed is 4 awg, it does not hurt to have one leg with a heavier gauge).

    Welding cable when listed as AWG (American Wire Gauge) size--a 0 gauge welding cable has the same amount of copper as a 0 gauge "home wiring" cable does.

    The bigger issue with welding cable is that with so many fine strands, that it is physically larger in diameter than other cable (solid or cable with fewer strands) so it is difficult to find swagged/crimp terminals that fit properly.

    In the end, the gauge of the wiring is based on current requirements and length/voltage drop.

    You can use this wiring calculator to work out the basic cable diameter requirements. And use the NEC book for the proper insulation and copper requirements for the wiring conditions (ambient temperature, in conduit or not, exposed to sun/oil/etc. or not, etc.).

    Remember voltage drop is very important in low voltage circuits... 2 volt drop at 120 VAC (or DC) is nothing... 2 volt drop on a 12 volt circuit and the 12 volt device will probably not even function. For longer runs, thicker/heavier cables need to be used--and frequently, the wire will not even fit the terminals, and folks have to trim down some of the "extra" strands to fit in the terminal blocks (not a problem as the cable is way over-sized because of the long run--the trimmed down portion will still safely manage the actual current flow).

    Regarding the ground wire--Typically 6 awg minimum (bare) is used in NEC for safety/reference grounding. If you have special conditions/requirements, you may need a heavier ground cable (the safety ground return, excluding the earth connection, needs to be able to trip the breaker/fuse if there is a short between hot and a grounded metal connection--such as a metal bench or water piping, etc.--something that most people don't worry about unless you are designing large electrical equipment/industrial buildings).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Wire Gauge Question

    Article on use of fine strand welding cable in PV applications: http://www.nmsu.edu/~tdi/pdf-resources/IAEI-1to2-05.pdf

    HTH,
    Jim / crewzer