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Thread: Table Saw use with Generator - Issues

  1. #1
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    Table Saw use with Generator - Issues

    Hey all,

    I've been using my Grizzly G0691 table saw with a Honda 240 volt generator for a couple of days. After converting one of my extension cords to plug into the generator (6-20P to L14-30P). The first day that I used it I noticed that I would have to hold the switch in for an extra second or two to let the mag switch engage and keep the saw running. I'm not sure if the had an effect, but let it also be noted that this was being done in an unheated shop in Minnesota where it was probably 10-20 degrees at the time (heat has since been added).

    The second day that I tried to use the saw, it would not turn on at all. So, I took the switch cover off to see if I could see anything obvious. I noticed on the switch that there was a blue bar accross one portion of the switch mechanism. So, I plugged it in and pushed the button. The saw turned on, but that switch has to be held in for the saw to keep running. So, I continued and am still using it in that manner (clamping that portion of the switch to keep the saw running).

    The next day I called Grizzly to see what the problem was and what I would need to do to get my saw operating properly again. The saw is about 2 years old, so past the warranty period, so I gave it to them straight and let them know I was using a generator to power the saw. The Customer Service Rep's response was "the saw is not designed to be powered by a generator." So, he proceeded to tell me that I needed to replace the entire magnetic switch (everything under the cover). I asked if I could just get the on/off switch (portion directly behind the green ON button), but he said that I needed the entire thing and they don't even carry just the on/off switch. The entire switch is $155 plus tax and shipping so probably at least $170 by the time it gets to my door.

    Knowing that I would continue to have to run the saw off the generator for the near future, I said thanks, but I'll pass on the part for now and keep running it as is (also hoping that I can maybe get just the on/off switch if that is indeed the problem or trouble shoot it more). The CSR also said that I could potentially damage the motor if I continue to run it off the generator. So, I asked how much a new motor would cost. $300. So, I'm already down the $170, and potentially $300 if my motor doesn't hold up. I don't really have a choice right now but to run it this way as I have a bathroom vanity and entire set of kitchen cabinets to build for my recently purchased house.

    Anyways, after that long explanation, has anyone else had similar experiences or have any thoughts on this?

    Thanks for any help or advice,
    Kyle

  2. #2
    Yikes! im not sure i would have tried that. One problem might be the cord you rigged. It might not be carrying enough juice to hold the switch. Another possibility is the generator isn't generating the proper amperage for the saw. Either way you are putting the motor at risk.

    How much would it cost to have an electrician wire up a 220? I bet less than $470. You could also get a basic 120v contractor table saw for less than that. They are designed to be used with generators.

    Hope you get it worked out, but I think I would look for alternatives.

  3. #3
    What model Honda generator - inverter type or no? There's a difference in how "clean" the power waveform is between the two; the Honda i series can run electronics.

  4. #4
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    Are you sure you wired that 14-30P correctly? It sounds like you may be getting only 125V to the saw.

  5. #5
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    Quote Originally Posted by David L Morse View Post
    Are you sure you wired that 14-30P correctly? It sounds like you may be getting only 125V to the saw.
    David, how are you making that conclusion? I'm not saying you're wrong, just interested in why you think that?

  6. #6
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    Your generator may be able to supply enough currant to run the saw, but not enough start up current, causing the voltage to drop to low to hold the magnetic switch in. I do not see how a table saw motor would not run on a generator that could supply the right current at start up, its a lot more the the run current. Would take a big generator.
    Bill

  7. #7
    If the generator is a non inverter it isn't at 60 htz, which is a problem for sensitive electronics but most motors can run on them without a problem.

    If it is a inverter generator if it is a cheap one then it isn't a pure sine wave which is a problem for some motors and sensitive electronics.

    If it is a pure sine wave inverter generator, you can run anything you want on it without problem , but the pure sine wave part makes the generator cost about 10x's as much as a non inverter generator of similar output.

    The benefits of inverter generators is they are very very quiet and sip fuel. The benefits of a non inverter generator is they are cheap per watt to buy.
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  8. #8
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    Generators aren't capable of supply large amounts of starting to current to motors, unless the generator is over sized to take this into account.

    Your generator will come with a rating that indicates the maximum motor load that can be connected, you should check this.

    Obviously if the generator is large enough, and it maintains proper voltage and frequency, your motor won't know whether it's connected to a generator or Niagara Falls.

    An extension cord that's too small (excessive voltage drop) will only make this situation worse.

    Regards, Rod.

    P.S. Although it won't affect this isuue, please make sure that if it's a portable generator you have properly grounded it for your safety.
    Last edited by Rod Sheridan; 02-22-2013 at 4:12 PM. Reason: Added PS

  9. #9
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    Quote Originally Posted by Kyle Kaldor View Post
    David, how are you making that conclusion? I'm not saying you're wrong, just interested in why you think that?
    1) You put a 30A plug on your cable so I assume that the generator has a 30A receptacle. This implies that the generator is capable of at least 20A otherwise it would have the cheaper 20A connector. 20A should be capable of running your saw.

    2) The type 14 connector has four pins: L1, L2, Neutral and ground. Your saw requires only three pins: L1, L2 and ground. 3 conductor S type cable is normally color coded Black, White and Green (in the US). For 125V applications Black is line, White is neutral and Green is ground. The plug or receptacle is a type 5 and is coded with Gold for line, Silver for neutral and Green for ground. For 240V Black and White in the cable are used for L1 and L2 with Green being ground. The type 6 device used here has Gold for L1 and L2 and Green for ground. The type 14 device adds a neutral pin that is coded with Silver. Since we are all used to connecting White to Silver in 125V situations it's very easy to make that mistake here. You should have Black and White connected to L1 and L2 (doesn't matter which) and no connection to the neutral (Silver) pin.

    3) When troubleshooting eliminate the simplest hypotheses first, in this case the miswiring of a connector, not the coincidental failure of a mag switch with it's connection to a generator.

  10. #10
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    Quote Originally Posted by Rod Sheridan View Post
    Generators aren't capable of supply large amounts of starting to current to motors, unless the generator is over sized to take this into account.

    Your generator will come with a rating that indicates the maximum motor load that can be connected, you should check this.

    Obviously if the generator is large enough, and it maintains proper voltage and frequency, your motor won't know whether it's connected to a generator or Niagara Falls.

    An extension cord that's too small (excessive voltage drop) will only make this situation worse.

    Regards, Rod.

    P.S. Although it won't affect this isuue, please make sure that if it's a portable generator you have properly grounded it for your safety.
    +1. What size generator (kilowatts), and what size tablesaw (motor HP)? Also, what guage wire in your extension cord, and how long is the extension cord?

  11. #11
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    Kyle;
    Don't run the saw on a generator. Find something else to burn up.
    Never, under any circumstances, combine a sleeping pill, and laxative on the same night.

  12. #12
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    I was just trouble shooting a generator issue for a friend yesterday. He had two dryers that would not start reliably, or run long without tripping a breaker. The math of what the generator was supposed to put out vs the need was ok. The dryers however used another 5-7 amps for the first min on startup, then get back down to the rated amps. A saw will be similar because of the weight of the blade from rest. Like Rob and Scott said. I went a bit further and checked the incoming power, and the volts fell off rapidly as the generator approached max draw, which of course makes the tripping breaker issue worse. Your saw may have a built in overload in the switch? IF it does, the same issue would apply. Just mentioning this because it is exactly what Rod described.

  13. #13
    does your generator speed up when drawing a load?
    this is a fuel saving device
    but some generators run full bore always or have a switch to toggle between full power and fuel saving
    I ran geneartors for years in construction and keeping it run full throttle worked best
    Did I use more gas? yes but I got

    from Honda site the say to have up to 3 times the amps to start some items

    Reactive loads contain an electric motor, which requires additional power to start, but significantly less power to run once it gets going. Typically starting power is 3 times the amount of power to run the application. Examples of reactive loads include:

    Refrigerators / freezers
    Furnace fans
    Well pumps
    Air conditioners
    Bench grinders
    Air compressors
    Power tools
    Some household appliances, like a furnace or refrigerator, have internal fans that come on intermittently. Extra wattage/power is needed to start the fan each time. Refrigerators also have a defrost cycle that requires power in addition to the compressor and fans.

    Reactive loads may also require additional power when the electric motor begins to work. For example, when a saw begins cutting wood, its power requirement will increase. This is not applicable for most household appliances.
    Carpe Lignum

  14. #14
    It should actually turn the same speed all the time. As the load increases, it becomes harder to turn the generator, and the throttle opens, keeping the speed constant. I suspect they just use a centrifugal governor to keep the RPMs constant. I just mention it so he doesn't think something is wrong with his generator when it's actually running perfectly.

  15. #15
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    Quote Originally Posted by David L Morse View Post
    1) You put a 30A plug on your cable so I assume that the generator has a 30A receptacle. This implies that the generator is capable of at least 20A otherwise it would have the cheaper 20A connector. 20A should be capable of running your saw.

    2) The type 14 connector has four pins: L1, L2, Neutral and ground. Your saw requires only three pins: L1, L2 and ground. 3 conductor S type cable is normally color coded Black, White and Green (in the US). For 125V applications Black is line, White is neutral and Green is ground. The plug or receptacle is a type 5 and is coded with Gold for line, Silver for neutral and Green for ground. For 240V Black and White in the cable are used for L1 and L2 with Green being ground. The type 6 device used here has Gold for L1 and L2 and Green for ground. The type 14 device adds a neutral pin that is coded with Silver. Since we are all used to connecting White to Silver in 125V situations it's very easy to make that mistake here. You should have Black and White connected to L1 and L2 (doesn't matter which) and no connection to the neutral (Silver) pin.

    3) When troubleshooting eliminate the simplest hypotheses first, in this case the miswiring of a connector, not the coincidental failure of a mag switch with it's connection to a generator.
    David, that all makes sense. I agree that with the 30A plug, I would think the generator should be capable of producing at least the 20A that I need for the saw.

    When wiring the plug, I put the black to the X pin, the white to the Y pin and the green to the ground pin (they were all labeled on the plug).

    I will double check my wiring to the plug.

    Quote Originally Posted by Scott T Smith View Post
    +1. What size generator (kilowatts), and what size tablesaw (motor HP)? Also, what guage wire in your extension cord, and how long is the extension cord?
    I'm not exactly sure of the generator size, but like I mentioned above, why would it have a 30A plug and not be able to produce 20A/240V? I am using quite a bit of extension cord. One 25 ft 10 gauge cord, one 15 ft 10 gauge cord, connected to the 14 gauge saw cord. I think this should be adequate.

    Quote Originally Posted by Myk Rian View Post
    Kyle;
    Don't run the saw on a generator. Find something else to burn up.
    Like I said, I don't have a choice, I've got a wife to keep happy and cabinets to build.

    Can anyone make sense of why this was working for a day and now all of a sudden does not work? What on the mag switch would/could have went bad. I don't really understand how they work.

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