Table Saw use with Generator - Issues

[Kyle Kaldor]

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

[Steve Keathley]

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.

[Don Welch]

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.

[David L Morse]

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

[Kyle Kaldor]

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?

[william watts]

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

[Joe Hillmann]

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.

[Rod Sheridan]

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.

[David L Morse]

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.

[Scott T Smith]

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?

[Myk Rian]

Kyle;
Don't run the saw on a generator. Find something else to burn up.

[Steve Rozmiarek]

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.

[phil harold]

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.

[John Coloccia]

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.

[Kyle Kaldor]

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.


+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.


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.

[John Coloccia]

You've got a simple magnetic switch in that saw. If it comes on when you hit the button, it should stay on. It bothers me greatly that holding the switch allows you to run it. I wonder if the overload trips if you can still hit the On switch and have it come on? Very strange. Maybe you can find a friend that knows what he's doing and can come by and help you out so you don't keep blowing up the table saw.

[David L Morse]

...I put the black to the X pin, the white to the Y pin and the green to the ground pin ...
That is the way it should be.

[John Coloccia]

Hmmm...lightbulb just went on. Does the motor run slower now than it normally does when it's running well? Does it make a "click" noise when you shut it off and it's spinning down? I have a feeling that your performance is so bad at this point that you're running on the starter winding the whole time, causing such a voltage drop that there's no longer enough current to keep the magnetic switch closed. That means you're frying your motor.

[Kyle Kaldor]

You've got a simple magnetic switch in that saw. If it comes on when you hit the button, it should stay on. It bothers me greatly that holding the switch allows you to run it. I wonder if the overload trips if you can still hit the On switch and have it come on? Very strange. Maybe you can find a friend that knows what he's doing and can come by and help you out so you don't keep blowing up the table saw.

Just to clarify my operating procedure. If, when the cover is removed, I press the small green on/off switch, nothing happens. If I press the blue longer bar, the saw starts up, but I have to keep that depressed in order to keep the saw running. That leads me to believe that only the On/Off switch is bad, but Grizzly claims that I have to replace the entire thing.

255171

[Kyle Kaldor]

Hmmm...lightbulb just went on. Does the motor run slower now than it normally does when it's running well? Does it make a "click" noise when you shut it off and it's spinning down? I have a feeling that your performance is so bad at this point that you're running on the starter winding the whole time, causing such a voltage drop that there's no longer enough current to keep the magnetic switch closed. That means you're frying your motor.

I haven't noticed any performance differences when running on the generator, other than the slightly slower startup.

[John Coloccia]

Ah, that makes sense. I misunderstood the symptoms. If you really wanted to you can hook up an appropriate momentary switch that bypasses the green on/off. It has to go between 14 and 13 on that relay. Keep in mind that EVERYTHING in that box is AC from your generator that can kill you, including the switch we're talking about...no wishy washy 12V DC in there.

Clamping the relay closed is a really poor solution. It looks like that will defeat the overload protection. It really would be very helpful if you had a buddy that knew a bit about this that could figure out where to get an appropriate switch locally and get it hooked up safely for you if you're not comfortable doing it yourself.

[Kyle Kaldor]

Ah, that makes sense. I misunderstood the symptoms. If you really wanted to you can hook up an appropriate momentary switch that bypasses the green on/off. It has to go between 14 and 13 on that relay. Keep in mind that EVERYTHING in that box is AC from your generator that can kill you, including the switch we're talking about...no wishy washy 12V DC in there.

Clamping the relay closed is a really poor solution. It looks like that will defeat the overload protection. It really would be very helpful if you had a buddy that knew a bit about this that could figure out where to get an appropriate switch locally and get it hooked up safely for you if you're not comfortable doing it yourself.

John, do you agree that it is only the on/off switch that is bad? I just can't imagine that the entire mag switch is faulty if it works by pushing the blue bar.

[Myk Rian]

Like I said, I don't have a choice, I've got a wife to keep happy and cabinets to build.
Surely she'll understand the situation.
Is it worth burning up the generator, saw, or both?

[Kyle Kaldor]

Surely she'll understand the situation.
Is it worth burning up the generator, saw, or both?

I'm not convinced that I'll burn up anything.

[Steve Keathley]

I'm not convinced that I'll burn up anything.Your saw, your risk, your money. Hope it works out for the best. Post some pics of the cabinets when you get them done.

[Larry Craft]

Inrush current!!! Your generator probably has plenty of power to run the motor, but not enough to start it. The three hp motor uses approx. 15 amps when running, but may need 50 or more amps to start. The low voltage created by the inrush current draw has burned up the contacts in the magnetic starter. They are not replaceable! You will have to replace the entire magnetic starter, it only comes as a unit. You are starting the motor on low voltage by forcing the the contacts closed. The heat generated in the motor this way can cause failure.

[Jim O'Dell]

I'm confused about not having another source of 220 power at the house. Is the electricity off? I would think a 10 gauge extension, or if it had to go a long way, an 8 gauge extension, while expensive, would be better than killing the saw. Is there not a dryer outlet you could commandeer when you need to use the saw? I'm guessing there is part of your current (no pun intended) situation that would keep you from doing this, and it just isn't clear to me, but I felt compelled to ask.
If you do need to get another mag switch, nothing saying it has to be the one from Grizzly, if there is another brand that will work that is the right rating and is cheaper, I think I'd go that route. I haven't priced mag switches, so the Griz unit may be very well priced.
I think I'd search for alternatives to power the saw. Building something small might be worth the risk. Building a set of kitchen cabinets would not be under the current (there's that word again) conditions. Jim.

[Kyle Kaldor]

I'm confused about not having another source of 220 power at the house. Is the electricity off? I would think a 10 gauge extension, or if it had to go a long way, an 8 gauge extension, while expensive, would be better than killing the saw. Is there not a dryer outlet you could commandeer when you need to use the saw? I'm guessing there is part of your current (no pun intended) situation that would keep you from doing this, and it just isn't clear to me, but I felt compelled to ask.
If you do need to get another mag switch, nothing saying it has to be the one from Grizzly, if there is another brand that will work that is the right rating and is cheaper, I think I'd go that route. I haven't priced mag switches, so the Griz unit may be very well priced.
I think I'd search for alternatives to power the saw. Building something small might be worth the risk. Building a set of kitchen cabinets would not be under the current (there's that word again) conditions. Jim.

The garage that I'm running my saw in is at least 200 feet from the nearest good power source (house). The gentleman that originally built the garage had no intention of running anything with significant power consumption. So, he buried a 12 gauge wire in the ground from another garage. So, under current conditions, if I have my lights on, a portable compressor will blow the breaker in the garage. Let's just say that this wiring situation is not ideal. I do have plans to add additional power to this building, but in the winter, it probably is not possible with the power company.

I think I'll look into running a LONG cord to the house.

[Kyle Kaldor]

Inrush current!!! Your generator probably has plenty of power to run the motor, but not enough to start it. The three hp motor uses approx. 15 amps when running, but may need 50 or more amps to start. The low voltage created by the inrush current draw has burned up the contacts in the magnetic starter. They are not replaceable! You will have to replace the entire magnetic starter, it only comes as a unit. You are starting the motor on low voltage by forcing the the contacts closed. The heat generated in the motor this way can cause failure.

Larry, thanks for the explanation. That's what I was looking for. I looked into the on/off switch portion of the magnetic switch. I can buy it online for $1.88. So, I do have options and this may be the first thing I try.

[Leo Graywacz]

The magnetic starter has 2 switches. The on and the off. The on switch is a momentary close switch. When you press the switch is conducts current, when you let go it stops conducting current. The off switch is a momentary open switch. It conducts current all the time until you press the button and then it interrupts the current flow.

It is very important that the off switch conducts current, it is what powers the latch relay. If this switch is bad or dirty the latch relay will not stay engaged. Have you tried to blow the switch contacts out?

Can you power the saw by household current to see if it functions properly? If it does then you know it is something that is caused by the generator. If it doesn't work then you know that there is a problem with the saws magnetic starter.

[John Coloccia]

John, do you agree that it is only the on/off switch that is bad? I just can't imagine that the entire mag switch is faulty if it works by pushing the blue bar.

I don't know what's bad. My guess is that the on switch is bad. That said, Grizzly is not a on switch supplier...the switch is part of the magnetic switch. It would be like trying to buy a knob for a radio from Best Buy....they don't sell knobs....they sell radios.

[Mike Cutler]

Kyle

I would try to bring the saw to the house and see if the performance changes.
As for running a saw off a portable generator question; While it's not an ideal setup, it is done everyday across the country with generators nowhere near as nice as a Honda. Cement mixers, air dryer fans, table saws, water pumps, dewatering pumps, trash pumps, etc. I've seen them all run off generators. (You oughta hear a generator try to start a cement mixer if it already has the cement in it. Whoa!!!!! You'll only make that mistake once.:eek:)
The only caveat I will add is that you should be monitoring your voltage with a meter. Make sure the motor isn't drawing down the generator output excessively. You should see a momentary droop to about 190 vac and then come back to a nominal 220-240. If the voltage stays low, with the saw running , you have too stop and find out why. The lower the voltage, the higher the current for a given load in general.

It's not outside the realm of possibility that the mag switch is trashed. The blue bar you're pushing in may be the external relay contact indication. Most contactors of that type have a similar bar. It's not supposed to be used to energize a circuit, it's an external indication that a relay is picked up. In an industrial application the relay contactor has a seperate thermal control device. This device performs a couple of functions. It monitors for excess current over time, which is adjustable,and it monitor for excess inrush current and will fault the contactor to protect the load and the contractor. In a small inexpensive application, like your switch, this feature is integrated into the contactor assembly and is not adjustable.
You do not need a mag switch to power a table saw. It is a very nice safety feature, but any 2 pole, 240 switch, rated for the proper current, will work. One of these switches will cost $20-$30 for a quality switch.
I work on motor contactor devices, and motor control/ protective circuits virtually everyday. It's what I do.

[Jim O'Dell]

The garage that I'm running my saw in is at least 200 feet from the nearest good power source (house). The gentleman that originally built the garage had no intention of running anything with significant power consumption. So, he buried a 12 gauge wire in the ground from another garage. So, under current conditions, if I have my lights on, a portable compressor will blow the breaker in the garage. Let's just say that this wiring situation is not ideal. I do have plans to add additional power to this building, but in the winter, it probably is not possible with the power company.

I think I'll look into running a LONG cord to the house.

That would be a VERY LONG EXTENSION CORD! I'm not sure 200' is very doable with an extension cord. I'd check an online calculator at minimum, and a electrician would be even better, to see what guage wire you would need to use to keep the voltage drop within tolerance. It is possible that the wire could be re-purposed to the shop when you do the electrical work there, but would probably be way overkill. (I kinda like overkill personally:D. In fact, I took the 14 guage pigtail off my 691 and ran 10 guage directly from the outlet to the mag starter. Have contemplated subbing some 10 guage for the mag switch to motor pigtail, but haven't ventured that far....yet)
Is there a garage attached to the house that you could take over temporarily for the cutting of the wood? Then assemble in the shop? I totally understand not wanting to do the electrical work during the winter. Heck, I'm in Texas and don't want to do a whole lot most winter days in the shop! What ever you decide to do, I think it would be cheaper than having to replace the TS motor. I do like the safety feature of the mag switch for tools. If I lost power, I wouldn't want it coming back on and turn the tool on by itself. Jim.

[John Coloccia]

For what it's worth, I routinely....well once a year, anyhow, run my shop off a generator, because the power seems to go out around here for a week at a time about once a year. I can't run any of my big tools because the tool AND the dust collector is just too much, but I run everything else, including my Sawstop...er...former Sawstop.

Grizzly is right to just want to send out the entire mag switch because it can be the coil in there too, not necessarily the start button. It can be the overload protection, not the switch at all. You can probe around in there and figure out what it is, but I always feel uncomfortable giving those instructions because it's the kind of thing that is so simple that if you know anything about wiring, it's trivial to do it, and if you know nothing about wiring, you shouldn't be doing it. My guess is the switch is bad, because switches break, but other things break too. You could be swapping one component at a time for a week until you figure it out.

After you do figure it out, it always good to ask, "Why did it break?". It's not designed to break. Is it really just a bad switch or are you doing something to break it? These things really do not like to see their power sag....various things, including the motor, will tend to heat up and heat breaks everything.

[Kyle Kaldor]

UPDATE

I checked all of the extension cords and all are properly wired to their respective plugs. The Honda Generator is a 6500 Watt with Digital Automatic Voltage Regulator.

[Prashun Patel]

You can analyze this to determine the reason, but I bet whatever went wrong was caused by the generator - and is not just coincidence. I don't trust a portable generator to regulate it's voltage on anything north of a computer printer. If you replace the switch, I would take the bet that you'll have the same problem repeat.

[Scott T Smith]

UPDATE

I checked all of the extension cords and all are properly wired to their respective plugs. The Honda Generator is a 6500 Watt with Digital Automatic Voltage Regulator.

Kyle, according to Honda's website a 3HP capacitor start / capacitor run motor typically requires a minimum of 6800 watts to start it. The start current is usually much greater than the run current due to the power required to get the motor up to speed. Tablesaw motors typically require even more due to the mass of the arbor and blade and the fact that it takes several seconds for them to spin up to speed. Additionally, if there is any significant distance between the generator and the motor, line losses will add resistance to the circuit - increasing the start up load on the generator.

By all means spend a few bucks to swap out the switch, but at the end of the day I think that your problem most likely is the fact that you don't have enough generator to pull the start up load required by your tablesaw. The fried magnetic starter is more likely the symptom - not the root cause.

[Kyle Kaldor]

You can analyze this to determine the reason, but I bet whatever went wrong was caused by the generator - and is not just coincidence. I don't trust a portable generator to regulate it's voltage on anything north of a computer printer. If you replace the switch, I would take the bet that you'll have the same problem repeat.

Prashun, I agree with you that my problem was caused by the generator somehow, and that it will happen again if I replace the switch.