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Old 11-05-2010, 01:29 AM   #1
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Generator size?


How big a generator do I need to drive a 13A circular saw? The basic theory/formula says W = A * V.
OK, so 13A * 120V = 1,560W
...but I've been using my faithful 25-year-old Honda 700W generator (1000W peak) to drive my old saw for years, no problems, and I think it's rated at 11A, which seems to indicate that it requires at least 1,320 watts to start it going. So why doesn't it blow the circuit breaker on my generator every time I pull the trigger?

...and will that old Honda power a 13A saw?

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Old 11-05-2010, 06:35 AM   #2
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Generator size?


I would expect that the amount of power required by the tool is somewhat related to the amount of work you are asking it to do. Even if a tool is rated at a certain level, if you are using it for light-duty applications, you may never need the rated power. In other words, a circular saw cutting through a 4x4, being pushed hard, takes more power than the same circular saw slowly cutting through a 1/8" sheet of plywood. I don't know how hard you push your tools, but this could be a reason you have been fine with the small generator.

I understand that generators often have a higher transient (peak) power capacity than for steady state. If a saw has a short need for higher loads (starting, for example), this might be considered a transient load.

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Old 11-05-2010, 07:39 AM   #3
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Generator size?


The saw would only draw 13 amp when you load it down to almost stalling. Or that could be the locked rotor amps.
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Old 11-06-2010, 11:48 PM   #4
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Generator size?


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Originally Posted by joed View Post
The saw would only draw 13 amp when you load it down to almost stalling. Or that could be the locked rotor amps.
Joed., Just trust me on this one the circualr saw they are famous for tripping the breaker if you push it too hard or burn up the motor one of the two.

I have destory couple like that { the curpit will be brush holders that where the first part will get hit on circular saw but for any other universal motor the feild is the primary spot for failure ( overheating )}

Merci.
Marc
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Old 11-13-2010, 12:01 PM   #5
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Generator size?


I apologize for not responding sooner, I was off grid for several days, just now catching up with email and home chores, remembered my question and logged on. All of your answers were spot-on, and each complemented and supported the others, which is really great. I was reminded that I have often popped the circuit-breaker with the old saw when a piece of lumber bound and the saw stalled. I use sharp blades, support the end of the work to prevent binds (most of the time), and I don't push my equipment...I'd rather let the blade do the work without overheating and coating the blade with charred varnish. And Marc, you are correct, I had to replace the brushes once - now I know why.

I suspect the old generator will do fine with the new saw. Thanks again to all of you for great answers (...that I could actually understand!).

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Old 11-13-2010, 05:35 PM   #6
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Generator size?


My smallest unit is a 2500 watt Honda,

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