Larry, Rule of thumb. If you parallel two identical runs, it's equivalent to increasing the gauge by three steps (e.g. two parallel 12 AWG are essentially equal to 9 AWG).
For two parallel runs of different sized conductors, add the circular mil area for both conductors, then using a wire table (such as a pocket guide), find the gauge closest to the total CMA to get the AWG equivalent. A calculator and pocket guide are more convenient than carrying a computer around to perform this calculation. You can also use the equivalent AWG, length of the run, and the rms amperage to determine nominal resistance and subsequent loss the in paralleled conductors. Dan --- On Wed, 2/2/11, Starlight Solar, Larry Crutcher <[email protected]> wrote: From: Starlight Solar, Larry Crutcher <[email protected]> Subject: [RE-wrenches] Parallel wire runs to increase size To: "RE-wrenches" <[email protected]> Date: Wednesday, February 2, 2011, 10:00 AM Wrenches, Some of our business involves repairing poor PV solar installations on recreational vehicles. So often we wind up installing a roof junction box and running a second PV to controller wire and then replacing the controller to battery wire size. For instance, we may find a 10 gauge wire run to the controller. We then add #8, #6, #4 or even 2 gauge and parallel to the #10 depending on power and distance of the run. My question: Is there a calculator or chart that will tell me what the combination of any two wire sizes equate to? example: #10 + #4 = X Thanks. Larry Crutcher Starlight Solar Power Systems powered by STARLIGHT™
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