Running a table saw and planer off a generator.

[Robert Wachtell]

I was wondering if it is possible to run my planer or table saw off a 7500 watt generator?

Should I be able to do it if I have correct hookup for the 220 volt machines?

[David Hawxhurst]

its possible. i would only run one at a time.
is the 7500w peak or continuos?

[John Lankers]

Yes you can I've done it with a Dewalt 746 table saw and a 735 planer, it's expensive though. If the saw or the planer have electronics of any kind I'd be careful and only use an inverter type generator.

[Erik Manchester]

As David said, you will be fine, contractors do this often enough.

[Robert Wachtell]

OK

I tried it with my planer and the generator started bouncing around a lot when I powered up the planer so turned it off quickly. By the way the motor does not start up on the plane. Generator just bounces.

I run the three prong planer off a wall outlet from the panel in the garage and it runs fine off of that.

I had to make a splice from the three prong planer plug to the four prong receptacle on the generator. An electrician told me nothing was wrong with the wiring in the splice plug.

Its a Generac 7500 watt generator.

Can't figure out why it bounces around?

Too much start up request for the generator?

[John Lankers]

Obviously something is wrong. You're saying the planer runs on 240V, what size is the motor? For 120V wiring you generally have Black (hot), white (neutral) and ground. For 240V you have 2 hot and 1 ground, you don't need the 4th wire (neutral) in this case.
I suspect either your wiring is wrong or the planer draws to much current on start up.

[Erik Loza]

I'm no sort of electrical or generator expert but sold a bandsaw to a customer in Hawaii once, who was off the grid and wanted to run it off a generator. The generator he had "should" have been able to handle the motor size but he told me that his experience was similar to the OP's. The saw would not start. Maybe the starting amps were too high? I'm not sure and lost touch with him but am curious to hear other's experiences on this.

Erik

[John Lankers]

I agree, the HP and AMP rating printed on the motor plate would be helpful.
We used to have starting issues with big handheld angle grinders back in the day running on 220V and 10Amp breakers, had to run the blade over the shop floor while hitting the switch at the same time to keep the breaker in.

[Dennis Ford]

Starting amperage is 5 - 6 times as much as full load running amperage. When the power is available, it only lasts a fraction of a second. A 7500 watt generator should be able to start a 2hp motor but may have trouble with anything bigger.

[Robert Wachtell]

Obviously something is wrong. You're saying the planer runs on 240V, what size is the motor? For 120V wiring you generally have Black (hot), white (neutral) and ground. For 240V you have 2 hot and 1 ground, you don't need the 4th wire (neutral) in this case.
I suspect either your wiring is wrong or the planer draws to much current on start up.

When I run the planer off the wall outlet I created it runs fine. In this case Two hot lines go the piggy backed double breaker on the panel and the ground line on the planer plug goes to the ground bar through the three pronged outlet I put on the wall next to the panel. Works fine.

As for the generator, when I take my three pronged 220 volt plug to the planer out of the wall outlet and merge it to the four pronged outlet on the generator ( this outlet has two hots, one ground and one neutral) I send the two hot lines for the planer to the two hot lines feeding out of the generator outlet and send the ground line from the planer plug to the ground line (green) on the generator outlet. This leaves the neutral line (white) on the generator vacant. Perhaps the ground line on the planer plug should go to the vacant neutral line on the generator outlet????

If that's not the issue then it must be too much startup amperage.

[Wade Lippman]

If that's not the issue then it must be too much startup amperage.
Ground goes to ground. (normally, home generator grounds aren't attached to anything at all internally; but that's a wholenother issue)

Your generator can put out a maximum of 31a.
A typical planer with a 3hp motor will draw about 15a. To start will require between 60a and 90a.
You don't have to be real good at math to answer your own question.

Ideally your generator should have tripped out on the overload; instead it was failing.

[John Lankers]

Warning: Do not connect the Ground to Neutral or vise versa. It's a safety issue.
I'm not familiar with your generator but have you tried to bring the engine up to full speed before turning the planer on? If the planer would draw more Amps than the breaker on the generator can handle it would simply trip.

[Robert Wachtell]

Warning: Do not connect the Ground to Neutral or vise versa. It's a safety issue.
I'm not familiar with your generator but have you tried to bring the engine up to full speed before turning the planer on? If the planer would draw more Amps than the breaker on the generator can handle it would simply trip.

I'm not familiar with "bringing a generator up to full speed". What else do I need to do besides turning the generator on and letting in run a minute or two in order to bring it up to full speed.

[Robert Wachtell]

Ground goes to ground. (normally, home generator grounds aren't attached to anything at all internally; but that's a wholenother issue)

Your generator can put out a maximum of 31a.
A typical planer with a 3hp motor will draw about 15a. To start will require between 60a and 90a.
You don't have to be real good at math to answer your own question.
.
Ideally your generator should have tripped out on the overload; instead it was failing.

You make it sound like the answer to my first post on this thread is no. You can not run a 220 volt planer on a 7500 watt generator. Start up request in amperage will be too high for the generator. The generator will be overloaded.

[John Lankers]

I'm not familiar with "bringing a generator up to full speed". What else do I need to do besides turning the generator on and letting in run a minute or two in order to bring it up to full speed.

You can try plugging in a trouble light, power drill or something else to trigger the generator to Rev up and then start the planer.

[Martin Wasner]

A trick for when there is a bunch of guys all running off of one 15a outlet is to bump the start switch a couple of times to get it moving, then go to full power on the tool. Tough to do if there's a magnetic starter though, and I don't know if it would work, but with my portable tablesaw that is what is often required on site to keep from tripping the breaker.

[Art Mann]

The whole issue has to do with the fact that starting current is often 2X or 3X the rated motor current for several seconds. Unlike the big generators, there is no flywheel of any significant mass to provide inertia to keep the rotor from slowing down rapidly. The rotation drops below sync speed for too long and the simple controller shuts it down.

[David C. Roseman]

Sounds like your Generac has an auto-idle feature. Is there a switch to turn auto-idle off? If so, it should then run full throttle.

That won't solve the problem, though, if start-up current draw is still too high for the generator even at full throttle.

[Harry Niemann]

Contact Generac.