generator/extension cord question


Hi everyone,
At the moment, I'm doing side jobs that require the use of a drill and a chop saw. I recently purchased an 8 amp Milwaukee 1/2 " magnum drill and I also bought some a couple of 100 feet worth of extension chords rated at 13 amp. This is adequate for the drilling I have to do through plywood and 2X4 boards on the forms set up to hold concrete on home slabs. The reason why I drill through the forms is to install the post tension cables.
I'm also looking to acquire a 15 amp Milwaukee chop saw for cutting the rebar pieces that will serve as concrete reinforcement. But what I need to get first is a generator, because in a few places where I've been sent to do jobs, the electricians haven't set the poles up and I have nothing to plug into. I have to end up borrowing someone else's generator but I need to get one of my own.
I'm looking to get the smallest generator possible because I have space limitations in my car. I was looking at the Coleman Pulse that has a maximum of 1850 watts (surge) but I'm not sure if that's enough. I guess it may be enough for the drill, but it probably won't be enough for either a circular saw or the chop saw. What would be the minimum wattage size of a generator to run something like a 15 amp Milwaukee chop saw or circular saw? I only play on running one thing at a time from the generator; I won't be running multiple tools simultaneously off the current.
Since I was planning or intending to pick up the 15 amp chop saw, I was wondering if the fact that the extension cords I have are rated at 13 amps or lower could present a problem? What I did today was pick up a 100 foot 15 amp extension cord so it matches the amperage on the chop saw. It was really expensive...at least over $60. Would it be a problem, from a safety perspective, if I used the 13 amp extension cords on the 15 amp chow saw?
thanks
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snipped-for-privacy@aol.com wrote:

Can't say I've tried it, but theoretically, 15 amps at 110 volts should be 1650 watts. And the chop saw won't be using 15 amps all the time (maybe just at startup and under very heavy loads), but I'd still definitely use the 15 amp extension. I'm sure someone will correct me if this theory doesn't translate nicely into practice. Andy
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On a 100 ft cord the voltage drop will over heat the cord wires, starve the tool motors and cause them to heat up very fast increasing resistance. The tool motors require a certain wattage (amps X volts). If it can't get the volts, it will draw more amps to get it's wattage, which will heat up wires and the motors more - snow ball effect. If your lucky, it will only trip the breakers .
Look at what the commercial pros use for cords. They aren't that big because they like to spend money on wire.
Pete
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snipped-for-privacy@aol.com wrote:
> At the moment, I'm doing side jobs that require the use of a drill and > a chop saw.
<snip>
Let's cut to the chase.
I've been to the movie, don't want the T-Shirt.
You need a "Contractor Generator" which isd a 10HP engine, 5,000W generator, probably $500-$600 range.
You need #10AWG extension cords, 100 ft MAX for the chop saw.
Use the other cord for the drill. (The generator has a duplex receptacle)
At the end of the day, the job will be done, your tools will be in the truck, in working order, ready to do the same thing all over tomorrow.
Lew
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I previously wrote:
> You need a "Contractor Generator" which is a 10HP engine, 5,000W > generator, probably $500-$600 range.
Change the oil (SAE30 Non detergent) every 40 hours.
(I did it last thing Sunday night, every week for over a year)
If you don't, premature engine failure.
(I wore out a couple eng-gen units before I figured that one out)
Lew
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Only if that is the oil that the manufacturer recommends. Follow the manufacturers recommendations for type and weight of oil.
I have never heard of any manufacturer that as disallowed warrantee for too many oil changes.
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the formula for figuring amp output is divide voltage into watt output and you will have the max amp output like this 4000 watt divided by 110 volt = 36.36 amp, also 12ga wire has a 20 amp capacity and should be fine on a 100ft. run if you have a 15 amp chop saw 15amp x 110 volts gives you 1650 amp draw. ross
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snipped-for-privacy@webtv.net (Ross Hebeisen) wrote in

It's a tad more complicated than that. When the manufacturer rates the generator, they do it with a resistive load. But a motor is an inductive load, and in an inductive load the current and voltage can be slightly out of phase, so that the peak current is flowing at something less than the peak voltage. This is referred to as the "power factor".
A typical power factor for a small tool motor might be 0.9, meaning that the real power drawn is 90% of the apparent power (the product of the volts * amps). So 15 amps with a .9 power factor is equivalent to a demand for 1833 watts.
Since the Colman generator the OP was looking at is only rated at 1500 watts, it's not close to running his saw. It'll be good for a motor pulling up to ~12.5A, but not more.
John
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snipped-for-privacy@aol.com wrote: [snipped for brevity]

Those Coleman Pulse generators are not designed to wind up a 15 watt chopsaw with a 100 ft cord attached to it. ( minimum 12 gauge. 10 ga MUCH preferred.) Those 'camper' generators are to power the airmatress inflators and maybe a a couple lights/fans/radio. They're also basically disposable... I can't imagine anybody fixing one of them.THE rule is: only cry once.
To hang your living off a 'toy' generator would be doing yourself a disservice.
My advice? Listen to Uncle Lew Hodgett.
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tysteel300 said: snip

Get a Honda. http://www.hondapowerequipment.com/ModelDetail.asp?ModelName=en2500
This little (affordable) generator will fit in your car's trunk and it has enough power for your requirements. The Coleman's may be fine for limited use but take it from someone who uses generators frequently, you will soon grow to hate it.
As with any generator, use the shortest/fattest cord you can and do service it regularly.
Dave
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I have used a Honda 2200 watt (104 pounds) for a number of years. It went to Mississippi for a while after Katrina but is now back. For one tool at a time it's just barely adequate. Chop saws and circular saws will run OK with it if they are brought up to full speed first and don't get bound in a cut or forced into the material. I have a wheel kit on it.
For what you want to do, it's going to take at least 3500-5000 watts of generator. I doubt that you will need to go to a 6250 rating. Problem is, now the thing weighs 150 pounds or more. It's at least a two person deal unless you can mount it on a 5x10 trailer and bolt it down. It will need the 4-5 gallon tank, not the little 1.5 gallon tank that goes empty in the middle of the job.
I use 10 guage cord, 50' long. Otherwise it's 12 guage in either 50' or 100'.
BTW, get the unit with the largest muffler available. Do not get the 4000 watt unit, 1 gallon tank and tiny hot-dog muffler. Your ears will thank you.
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snipped-for-privacy@aol.com wrote in news:1153102458.483541.94900@ 35g2000cwc.googlegroups.com:

Probably not enough for the saw. Plus that's a light duty generator with a Briggs engine, intended for campers and folk like that, it won't last on a job site. Try the Honda EU2000 - it can probably handle your chop saw, and it will last for years.

Yes, especially since the generator is going to be marginal for the load.

Don't do that - you're wasting your money. Put the generator where the saw is, and don't use an extension cord at all. Any cord, even a thick one, is absorbing some of the power; you have none to spare with the kind of generator you're looking at.
John
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Hi my friend,
These craftsmen have given you a whole lot of good advice..
You have a choice, to buy the right power supply and cables to start with, or to constantly be buying new saws, drills etc.
The key is to have a generator that will provide at least twice the largest draw in watts or amps that you will ever expect to use. The reason is that the 15 amp chop saw that you expect to buy, will use very much more than 15 amps on start up, up to 3 times that much amperage on start. The surge rating.
While it is true that that kind of current draw will only be momentary, it still is enough, that when you are using using a power source that is not powerful enough, that you will over heat the motor on startup, so every time that you start the motor, you will be cooking the winding, and you can only do that just so many times before it fails.
The formulas given already are close enough to put you into the ball park, but they are for DC current. Those AC current formulas are a bit different, and I know that you do not want to get into those formulas that gets you into phase angles etc.
So, take the advice of all these fine craftsmen.
1. Buy the biggest generator that you can get, even if you have to haul it in a trailer, or tie it on top of your car. 2. Buy the heaviest gage extension cords that you can get your hands on. That way when you have to extend out 200 feet from the generator that you will not burn up your saw the first time that you use it. 3. Never use a 100 ft cord when a 25 foot, or 50 foot, cord will do the job. you can always use 2, 50 foot cords to reach 100 feet, a 25 foot and a 50 foot cord to reach 75 feet, but a 100 foot cord when used at 25 feet is still 100 feet, with the same resulting voltage drop. 4. Do not ever go below the manufacture's recomendations for size and length of extension cords.
Take it from those of us who have learned the hard way by breaking one or more of these rules, and thus burning up our very expensive tools. Your investment now in the right power equipment will save you $$$$$ in the future.
Zap
snipped-for-privacy@aol.com wrote:

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