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Thread: 140 foot run voltage drop and timers

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    140 foot run voltage drop and timers

    Hi all, I have concerns about distant runs, voltage drop and intermatic timer specs. In a nutshell, when dealing with wire gauge sizing, does not the run need to be the same gauge all the way through line to load, even through the timers (switches)?


    My pool's subpanel is next to my main panel 10 AWG wire 140 feet of distance to the equipment. This is a 230v single phase, 1.5 HP Jandy full rate 2 speed filter pump. Rated to draw 10/3.5 amps. On same circuit is a 3/4 hp Polaris cleaner booster pump. I'm on my third filter pump, 2nd booster pump in 9 1/2 years. I bought the 1.5 HP Jandy 2 speed to address poor performance of my water features which are on the same return lines as my 5 pool returns. On low speed to the waterfall sheet water features are underperforming so the full rated pump has enough torque at low speed to address this issue. And I intend to run on low speed most of the time except to run the cleaner (for those who say this pump is overkill!)

    The original electrician ran 10 AWG THHN from the subpanel to the equipment. Everything I have now learned says there should be a minimum 8 AWG wire required. Given there are two pumps, even 6 would be better or moving the sub-panel closer to the equipment (with a 4 AWG from main) would reduce the run distance; for now its the 10 AWG. Here is my concern:

    I have the Intermatic 104/106 timer configuration to run the filter and cleaner with the 106 to control the hi/lo 2 speed. All of this works but I am concerned about the timers. The gauge wire inside the timers is 12 AWG and the wires to the motors are 12 AWG!

    It appears the 10 AWG size from panel to pump is marginal at best.
    Upgrading to 10 AWG all the way to the pump does not address the timer's internal wire gauge.
    So is it necessary to rewire the timers with 10 AWG? Or even go 8 AWG from sub-panel to pumps?
    8 AWG wire seems too fat to easily put into the timer.

    I find nothing on Intermatic's website about support for larger wire gauges to address possible voltage drop issues. Does the wire gauge need to be same all the way out through the timers to the pump terminal connections? Or is there some magic about voltage drop to where the timer can be a lighter gauge?
    20000 Gallon pool built 2006, 2 skimmers, 2 drains, waterfall with separate pump, and 3 scupper waterfeature on main return line. Polaris 280 cleaner with booster pump. Filter pump Jandy 1.5-2 full rated with 104/106 2 spd Intermatic timer configuration.

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    pabeader's Avatar
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    May 2015
    Dallas Ga

    Re: 140 foot run voltage drop and timers

    This is a good one. Think of it like this:
    From subpanel to timer is a pair of resistors (the 10ga wire) from the timer to the motor is another pair (the 12 ga wire).
    So there are two sets of voltage drop the one up to the timer and the one beyond the timer.
    The question becomes one of lengths. The distance from the timer to pump is much shorter so it contributes a smaller drop vs the one from the subpanel to the timer.

    Have you taken actual voltage measurements? From what I remember you should only be seeing around 3-4 volts loss at the motor.
    Bob - Palm Beach by San Juan Pools. approx 5000 gals Pentair 320 cartridge filter (all new guts installed by me) Goldline SWG Intermec 104 TImer Test kit K-2006-C

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