No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?

nicd

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  • / No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?
I own a 13 amp electric lawnmower and need an extension cord that is 65 ft in length in order to reach the farthest point in my back yard. Can a problem occur for the lawnmower if I connect a 15 ft 16 gauge extension cord to a 50 ft 12 gauge extension cord? The gauge rating for 13 amps at 100 feet is 14 gauge, so it shouldn't be a problem since the 50 ft cord is 12 gauge with the remaining 15 ft is at 16 gauge? Will a 100 ft 12 gauge bring more electrical current to a lawnmower than a 50 ft 12 gauge + 15 ft 16 gauge, or are they about the same? I want my electric lawnmower to be as powerful as possible, they don't sell 65 ft 12 gauge extension cords, and the 75 ft cords are too expensive.($70 Can. with shipping).
 

reynoldston

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  • / No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?
I guess you need to look at it this way. Fill your 5 gallon gas can 5 times you have paid for your extension cord. Then if you take good care of that extension cord it should last you a life time along with many years of use out of your mower. Don't forget you will still need maintenance on you mower, lube axle bearings, motor brushes, and sharpen the blades.
 

Telesis

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  • / No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?
You are better off (by only a small and insignificant margin) using the 50' 12ga + the 15' 16ga. I'll bore you with some numbers...

The 100' 12ga will have a voltage drop of 4.94 volts at 13amps.

The 50' 12ga will have a voltage drop of 2.47 volts and the 15' 16ga will drop 1.95 volts for a total drop of 4.42 volts.

The difference is a whopping .52 volts which is only a 0.43% additional loss.

BOTTOM LINE, use either. The difference will not be noticeable!
 

MowerMike

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  • / No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?
If you really care about getting the best performance out of your AC motor, then you want the maximum voltage drop in your power cord to be 3% or nominally 3.6 volts, which means using a 75' 12AWG cord. Also, using two cords means an additional connection that can add to continuity problems. Letting the motor voltage drop below 115 VAC puts extra stress on the motor than can cause it to overheat and shorten its life. Saving a few bucks on a power cord is being penny wise and pound foolish.
 

Bwells

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  • / No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?
Mow with the 50 footer only and listen. Then add the 16 ga and see if there is a change. I would expect not.
 

Telesis

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  • / No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?
I'll respectfully share the following:

Most corded lawnmowers don't use AC motors, they use Permanent Magnet DC motors (PMDC) driven from a full wave bridge rectifier. (this is due to the torque requirements of a lawnmower application)

The power company will only 'guarantee'(I use that word loosely!) a nominal 120VAC +/- 5% (114vac to 126vac). The NEC allows for a 5% variation too.

NEMA (National Electrical Manufacturers Association) recommends motors be able to run at +/- 10% nameplate rating satisfactorily(not necessarily optimally)

Given this, you can see that achieving a 3% variance would be hard when the power company says it can only achieve within 5%. I am unaware of any substantive negative consequences that take place when you hit 3%. I've been an electrical engineer for 37 years and worked in a lot of residential, commercial and industrial locations and with a bunch of different kinds and sizes(up to 5000HP DC!) of motors, and I've seen supply voltages vary even more than the power company's stated +/- 5% (I've measured close to 10%!) In my personal experience and based on NEMA specs, I would typically not get too concerned until voltages are under or over by 10% (obviously application dependent)

I agree that the addition of a second cord adds a potential source of a problem but I think using a little common sense when connecting them minimizes it. I suspect you'll hear the difference in performance if a problem develops which causes a significant drop where they are connected.

BOTTOM LINE stays the same. Of course, always try and minimize voltage loss and given the specific facts here, IMHO the mower will be just fine and happy with the two cords. :smile:
 

nicd

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  • / No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?
better off (by small insignificant margin) using 50' 12ga + the 15' 16ga.
The 100' 12ga will have a voltage drop of 4.94 volts at 13amps.
The 50' 12ga will have a voltage drop of 2.47 volts and the 15' 16ga will drop 1.95 volts for a total drop of 4.42 volts.
difference is .52 volts only a 0.43% loss.
I kind of thought that, 50 ft 12 g plus 15 ft 16 g would bring ever so slightly more current than a 100 ft 12 g, but even better would be if i buy a 15 ft 12 gauge and use that instead of 16 g, but ever ever so slightly of a difference. I'll run the 15 ft across on my back deck so the connection can never be on wet grass, then the 50 ft will reach my entire backyard. I thought there might be a problem of plugging a 12 gauge cord with 16 gauge since the voltage may flow differently since the wires are different size but that should not be the case.
 
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nicd

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  • / No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?
Mow with the 50 footer only and listen. Then add the 16 ga and see if there is a change. I would expect not.
Yea the power of the motor would almost be identicle. Week ago i actually compared plugging a 80 fter 16 gauge into my lawnmower to hear how high pitched the motor runs compared to plugging a 15 fter 16 gauge and the motor sound was ever so slightly higher pitched(more powerful) when using a 12 ft cord compared to 80, but ever so slightly.
 

bertsmobile1

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  • / No problem if I connect 15 ft 16 gauge extension cord to 50 ft 12 gauge?
The problem will be with your mower.
A voltage drop will cause the mower to generate extra heat.
Most domestic electric tools do not have any bearings so the armature runs directly in the plastic case.
Again to save costs the case is thermo plastic so will get soft when heated.
Heat generating motor in a heat softening case does not precision make.
So if it is getting hot, stop & let it cool down.

I killed 2 garden shredders before it dawned on me what was happening.
In my case the solution was a 100' roll of flat wire ( the stuff you wire your house with ).
Because this wire has strait running wires you get a lot less voltage drop than normal twisted cable.
The sheath is not as strong, resistant to cutting or UV because it is made to live between your walls, thus it only comes out for specific jobs.
However in your case you could use a similar cord for the first cable.
That of course would mean mowing the close sections of your yard then pulling the flat wire out to do the rest.
Electrically it is almost the same as putting an outlet 30' away.
 
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