# 10 gauge extension cord for 10" saw?



## SAW.co (Jan 2, 2011)

Yesterday I purchased the 10" Bigfoot with a new HD77 saw.
The instructions tell me that I can only use a 10 ga cord but the saw came with a 14 ga cord, standard for 15 amp motor. I think?
Now I also know that a 15 AMP circuit is normally a 14 ga wire.
My question is what am I going to gain by using a 10 ga. extension cord when the saw cord is 14 & the plug is wired 14 or 12 at best?

The warrantee states void if I use any other cord than 10 ga.
Can someone put this in layman's terms for me please....

P.S. All my extension cords are 12 ga & in vary good condition.


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## KnottyWoodwork (May 23, 2010)

My carpenter brain remembers that it's a distance to size ratio. Like a 50' 12gauge could work, but to run 100', you'd have to step it up to a 10gauge.


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## Leo G (May 12, 2005)

Voltage drop is the name of the game. Depending on how much current the saw draws will determine the voltage drop across the cord. Most motors can handle 10% voltage difference and still function properly. If you are just using a 25' cord a 12ga would be fine. Any thing longer and you might think about getting a heavier gauge.

But it all depends on the current draw on the saw.


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## parkers5150 (Dec 5, 2008)

what Leo said:thumbsup:


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## GettingBy (Aug 19, 2010)

SAW.co said:


> I can only use a 10 ga cord


What max length of #10 is allowed by the manuf? With that number you can figure any length of any gauge cord larger than #16.


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## SAW.co (Jan 2, 2011)

Leo G said:


> Voltage drop is the name of the game. Depending on how much current the saw draws will determine the voltage drop across the cord. Most motors can handle 10% voltage difference and still function properly. If you are just using a 25' cord a 12ga would be fine. Any thing longer and you might think about getting a heavier gauge.
> 
> But it all depends on the current draw on the saw.


So, you're saying voltage drop is the effect of work load on the saw? 
Like the difference between cross cutting a nice dry 4x4 or ripping a green 4x6 with a huge crown in it.


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## Leo G (May 12, 2005)

Yes. Voltage drop is increases as the current draw increases.

I don't see the problem.

Here is a calculator

http://www.csgnetwork.com/voltagedropcalc.html


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## Tinstaafl (Jan 6, 2008)

SAW.co said:


> So, you're saying voltage drop is the effect of work load on the saw?


You got it. Just like when you press on your truck's accelerator to go up a steep hill with a heavy load--and consequently guzzle quite a bit more fuel, the saw needs more current when working harder. 

Voltage drop is directly related to current flow. If you lose 3 volts at 1 amp, you'll lose 6 volts at 2 amps. The net effect when using a light-gauge cord is that under heavy load, the saw won't get enough juice to run at optimum speed, and will tend to overheat as well as bogging down.


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## SAW.co (Jan 2, 2011)

OK I get it now but what I still trying to grasp is like with most older homes I work in the plugs are usually a 14 sometimes a 12 so if I plug in 50' of 10 its that much better I see it like this if you have a 1/2" pipe & you size up to a 3/4" you're not getting more water.


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## griz (Nov 26, 2009)

Hey SAW, I've been running Big Foots & the old big Makita Beam saws for awhile. Never went over 50' w/a 12ga cord. Didn't run a 12ga off a 10 ga either. Check the voltage at your starting point. If you're in doubt just run the 10ga. I've got about a 50/50 mix of 10 & 12 ga cords.


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## Tinstaafl (Jan 6, 2008)

SAW.co said:


> I see it like this if you have a 1/2" pipe & you size up to a 3/4" you're not getting more water.


I know what you mean, and it is a bit of a brain-twist to get why they want you to use the heavy cord if it's plugged into a lighter-gauge supply line.

Using the water pipe analogy, 50' of 1/2" pipe plus 50' of 3/4" pipe will allow more GPM than 100' of 1/2" pipe. :thumbsup:


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## Railman (Jan 19, 2008)

As previously stated, a smaller cord will have a bigger voltage drop. Less voltage will increase the amp draw for the same work load. If you want to run it on 12ga, keep the work load low on the saw. Otherwise, buy a 10 ga. Dull blades, & poor cutting teqniques will kill way more motors than small cords. The amp draw will be determined by the work load, & voltage available. Lower the work load & the amp draw drops. 

Distance is the key factor to cord size.
Joe


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## jamesdc (Aug 27, 2010)

Bigfoot recommends the 10 gauge cord due to too many problems with people destroying the motor by running it off 100+ feet of 12 or smaller cord. When you equip a skil with the bigfoot kit it puts ALOT more strain and increased power draw on the motor. On my bigfoot saw I ditched the wimpy stock 14 gauge cord and direct wired in a 35ft 12 gauge cord. I won't run the saw off more than 75ft of 12 gauge cord and certainly nothing smaller, and try to plug into a 20 amp breaker whenever possible. I've even noticed a slight difference in power when plugged into a 20 amp over a 15, plus alot less tripped breakers. Just look for the 20 amp outlets on the spider box or if your working in existing homes I try to plug into the outlets closest to the washer and dryer as they are usually 20 amp. Of course a quick trip to the panel will tell you any other areas of the house that are on 20 amp breakers.


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## Splinter hands (Aug 31, 2011)

Length of the cord is the main factor here that is why the saw comes with the 14ga cord. If you plug the saw in directly you have only the length of the original cord so 14.ga is fine but say you need to go 100 feet, then by the time it has run through 100 feet of ext. cord you no longer will have 15 amps with a 14 ga. cord. You can relate it resistance. Smaller wire =more resistance larger wire= less resistance. I don't know the actuall #s but hypothetically, run 100 feet of 14 ga. and at the end you only get 11amps. run 100 feet of 10 ga. and at the end you still have 14.5-15 amps. Not enough amps = a burnt up motor on your saw because when a motor is ran on too low amps. it will heat up. Hope this makes sense. I am no electrician but that is what I know about the situation. Good luck and don't burn up your new saw. Your best bet is to just buy a good 10 ga. cord, you will use it more than you think if you have it.


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## 480sparky (Feb 1, 2009)

There's two things missing from everyone's equation..... the wire between the fuse/breaker and the receptacle you're plugging in to, and other loads that may be on the same circuit. Both those items have a direct bearing on voltage drop.

However, the manufacturers cannot account for such a huge variables, so they may well tend to err on the side of caution when figuring extension cord sizes.

A lightly-loaded, short (length-wise) circuit may only need #14 for a 100' cord. The next job may have a bunch of other stuff on the circuit, and have building wire longer than the state of Texas, necessitating even #8.


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## griz (Nov 26, 2009)

480sparky said:


> There's two things missing from everyone's equation..... the wire between the fuse/breaker and the receptacle you're plugging in to, and other loads that may be on the same circuit. Both those items have a direct bearing on voltage drop.
> 
> However, the manufacturers cannot account for such a huge variables, so they may well tend to err on the side of caution when figuring extension cord sizes.
> 
> A lightly-loaded, short (length-wise) circuit may only need #14 for a 100' cord. The next job may have a bunch of other stuff on the circuit, and have building wire longer than the state of Texas, necessitating even #8.


As usual you are a wealth of info....:thumbsup:

We were all sounding pretty good until you showed up...:whistling

Don't you have pictures to take or preferably cookies to bake...


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## 480sparky (Feb 1, 2009)

griz said:


> ..............Don't you have pictures to take..........


How 'bout some 'shrooms?


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## griz (Nov 26, 2009)

That's pretty cool:thumbsup:

It's been said before, you have a new profession when you quit being a Sparky...:thumbsup:

Old Sparkies never die... their conductors just aren't solid anymore...:clap:


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## 480sparky (Feb 1, 2009)

griz said:


> That's pretty cool:thumbsup:
> ...........



Here's the shoot:












See the two other mushrooms in the background? (upper left)


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## Splinter hands (Aug 31, 2011)

Quite the set-up for a pic. of a mushroom. No wounder why my pics. are no good. Keep the pics. coming they are awesome. Hows the new website working for you? You have some nice pics. on there.


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