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Thread: Not satisfied with SawStop's answer?

  1. #1

    Not satisfied with SawStop's answer?

    I just finished assembling a recent SawStop purchase, an ICS with a 5hp single phase motor. I was prepared to install 10/3 SOOW cable to the saw but the supplied strain relief on the SawStop terminal box is too small and the opening on the terminal box is sized for 1/2" conduit. SawStop technical support stated that 12/3 wire is OK. I looked inside the cabinet today and found all of the strain relief fittings to the motor and contactor box are the larger size for 3/4" conduit. I still think 10/3 cable is more appropriate for a 5hp motor and the strain relief fittings should be larger. Comments?

  2. #2
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    10/3 would be preferable, assuming this is for 240 volts. If it's a short run, 12/3 would be ok. Ampacity for typical SO or similar cable is higher when only two conductors are current carrying (as they would be for a 240 motor). Typically 25 amps instead of 20 amps with 3 current carrying conductors. That's going to be close for a 5 HP motor running at full load, but as a practical matter, you probably won't often run at full load for long periods of time.

    A step drill makes quick work of enlarging the knockout if you don't have or can't borrow a greenlee punch.

  3. #3
    It's a short length, so voltage drop is not much of a concern (unlike, say, a long run to a panel). And it's exposed - not hidden in a wall - so its ability to dissipate heat is much better. So you can get away with smaller gauge than you'd use for a service conductor.

    Just looking at a random SO cable vendor's ampacity table, I see a 12/3 cable rated for 25A in single-phase service. That's good for ~8HP.

    Use the 12/3.

  4. #4
    I'm betting the SawStop engineers know what they're doing.

  5. #5
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    NEC 2017 Table 400.5(A) (1) states that 12ga SOOW cord is approved for 25 amps in a 2 conductor application.
    Scott Vroom

    I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.

  6. #6
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    Ha, dont worry Steve, SawStop kinda knows what they're doin...
    If at first you don't succeed, redefine success!

  7. #7
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    I wanted a longer cord for mine (3HP), so I just cut the cord to about a foot long & put a twist lock plug on it. I then made a longer extension cord using 12/3 & twist lock connectors. It is so cramped in the control box that I didn't want to mess with it and not take a chance on messing up the warranty.

    But ya, like the others said, what SawStop built it with will work fine.

  8. #8
    My used cb (ICS) came with 10/3 hooked up. I checked all connections and they seem to fit on mine.

  9. #9
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    Ask them why they wasted money on 3/4" fittings if they do not need the larger cable.
    Bill D.

  10. #10
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    Steve

    You're not limited to just SOOW/SJOOW cord. 3/C 10awg comes in other outer jacket materials. PVC, TFE, etc.
    Go to your local home center and measure the diameter of the 3/C #10 and then go over to the extension cords and find a #10 cord with a PVC jacket and measure that. It will probably fit through that 3/4" conduit connector.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  11. #11
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    Quote Originally Posted by Paul F Franklin View Post

    but as a practical matter, you probably won't often run at full load for long periods of time.
    This is my thinking. If I am pulling full current for continuous time frames on a 5hp table saw I would worry my setup is dangerous... (you production guys can set me straight, but as a hobbiest I havent come close to pushing the limits of the 3hp saw even - sharp blades and proper technique goes a long ways)

    Code already has a certain safety margin built into it, so doesnt seem necessary to add another layer of margin on top of that.

    What rating is the socket you are plugging it into? (I assume 30A outlet?) I am not an electrician, and on 'most' of my equipment the wall wiring (sized for 30A wiring/sockets/breakers) feed a piece of equipment that has a cable and internally wiring rated for much less. Short distances so its not a Vdrop concern. Then a motor has internal protection and may be treated a little differently as a load than say pure resistive loads.
    Last edited by Carl Beckett; 07-05-2018 at 7:14 AM.

  12. #12
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    I would put 10 gage wire on so I can use 30 amp breaker. If go with 12 gage wire would need 20 amp breaker. Seen one site that listed amp draw of 20.8...

  13. #13
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    Quote Originally Posted by eugene thomas View Post
    I would put 10 gage wire on so I can use 30 amp breaker. If go with 12 gage wire would need 20 amp breaker. Seen one site that listed amp draw of 20.8...
    This is false logic. Aside from the fact that The NEC does not cover cord and plug installations if this logic held true every single table lamp in America would be unsafe since they are all wired with 16 or 18ga cords and plugged into 15 and 20 amp circuits. As posted above, #12 S cord is listed for 25 amps continuous, there is no need for anything larger. A table saw in a hobby or one man shop is intermittent duty at best, it’s not like a heater that may run continuously at full load for hours on end.
    Last edited by John Lanciani; 07-05-2018 at 8:12 AM.

  14. #14
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    Many 10/2 + gnd portable cables will just BARELY fit through a 1/2" romex connector.

    Bring the connector to the store and see if the cable fits it... I used drop of dishsoap last time, was snug, but worked out for air compressor 30 a ckt.

    I would have used a step bit to enlarge to 3/4" KO, but the Condor pressure switch housing wasn't overall agreeable dimensions to accept the bit.

    Marc
    I'm pretty new here, not as as experienced as most. Please don't hesitate to correct me

  15. #15
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    Ya know John. I really don't care what is the NEC. I care about what makes sense to me. So in my shop if tool takes more than say 20 amps gets cord with breaker rated for more. But you seem to be the expert.

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