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too small a wire

D

Dan-IA

Member
I hear this trotted out at me regularly, an outright accusation that my outdoor extension cords and trouble lights are too light a cord to be running electric motors or battery chargers.

In this particular case I was running my electric log splitter off a trouble light. Between it and the extension cord I think I might be running 40 feet or so of 14ga wire and the electric log splitter runs the motor intermittently (only when the ram is pushing) and it is a 1500W motor on the splitter.

So is there an obvious and simple way to know if I'm overextending my wire? I havent noticed the wire getting warm and don't check voltage drop or anything, if it runs I use it.
 
Go to your favorite hardware store and read the labels of the different size cords and you should be able to determine what you should be using.
 
sounds like the motor has an internal low voltage breaker or a thermal overload. You shouold have at least 12 ga wire. I would use my 10 ga cords for that application. go get a dedicated 12 or 10 gA at least to within the length of the spliktter cord. Henry
 
Without at least a VOM or digital multimeter and/or experience there is no "obvious and simple way to know....

That said, a good rule of thumb for the uninitiated is: Lamps only on 14 ga wire. SMALL motors and most power tools can be safely run at the end of a good 100' 12 ga cord.

Dean
 
Compare the time for the motor to get up to speed with and without the extension cord. You'll want a cord with fatter conductors. Remember the induction motor draws 5 to 6 times running current while its getting up to speed, that's when the voltage drop is most critical. And extending start time raises the motor temperature a lot faster. Then it won't have the guts for splitting it could have with a shorter or heavier cord.

Gerald J.
 
The rule is very simple, 14awg should handle 15 amps, 12 awg 20 a. Power loss is calculated P= amps squared times ohms, I squared x R. However this doesn't mean much to the average person. The longer the wire the more R becomes. Another simple way to determine if you are overloading wire is to determine if it is getting hot. Electrical power losses are converted into heat energy. When it comes to motors, you have what is called lock rotor amps, the starting amps, which is many times the running amps. If your motor struggles to get started you need heaver wire. My advice is to buy only 12 guage extension cords. They may cost more, however they are cheaper than buying motors. As for battery chargers, most of them use very little current. However, heavy duty chargers, like those used on golf carts do. Go to Harbor Freight and when their voltmeters are on sale for $2 get one. Simply measure the voltage at the end of the extension cord when nothing is turned on and then measure it when it is under load. My rule of thumb is if you drop below 105 vac, you need a better extension cord. I'm sure that other people may have longer or shorter thumbs.
 
(quoted from post at 11:47:29 01/02/10) I hear this trotted out at me regularly, an outright accusation that my outdoor extension cords and trouble lights are too light a cord to be running electric motors or battery chargers.

In this particular case I was running my electric log splitter off a trouble light. Between it and the extension cord I think I might be running 40 feet or so of 14ga wire and the electric log splitter runs the motor intermittently (only when the ram is pushing) and it is a 1500W motor on the splitter.

So is there an obvious and simple way to know if I'm overextending my wire? I havent noticed the wire getting warm and don't check voltage drop or anything, if it runs I use it.
Click to expand...
he obvious & simple way is to measure the voltage at the motor to be sure it is within the motor's specified voltage operating range. Done!

Now, your 1500watt motor on 110volts would result in 13.6amps, and 13.6 amps thru 80 feet of 14GA wore (2-way path) will result in 2.7 volts loss or drop in your wire. Typically 5% is maximum allowed for the total circuit, which included both your extension cord & the wiring feeding the receptacle that it is plugged into (some design for 2 or 3 % on motor loads). 2.7/110 X100= 2.4%.
You look OK to me. But remember that I don't know what you have ahead of that receptacle. Motors do have a starting current surge much higher than the run current & it is expected & allowed that the 5% will be exceeded during start up, however, if the start up drop is too great, the motor may not start at all. This is particularly a problem on motors starting while under a load such as some air compressors. In such cases, larger than 'standard practices' wiring may be required. And, finally, a motor which is supplied a lower voltage than designed for, will run hotter than if correctly supplied. If you are fortunate enough to have power delivered to you place at 125volts, then you have more room for loss (voltage drop) than if delivery is 110volts, too.
It is a p!zzer there there are no simple answers isn't it? I guess there sort of is a simple answer: get a big old honkin 10GA wire and over kill the sucker, then your done.
 

Another vote for 12 gauge wire. Had a 14 ga. burn out on me at the connector, which is another thing you should keep an eye on since there is more flexing of the wire there.

KEH
 
Dan, its NOT Rocket Science and as youre already aware Im sure,,,,,the smaller the wire and the longer the run THE MORE VOLTAGE DROP. One limiting and crucial factor IS GETTING THAT MOTOR STARTED as it might draw 5 or 6 times the run current to get it up n running.

WITHOUT doing any calculations, a 40 ft run of 14 gauge wire should do the job, subject to the motors exact specs...BUTTTTTTTTTTT for motors especially motor starting IT SURE WOULD SUIT ME BETTER IF YOU USED 12 GAUGE. Its just that heavy current draw at start up that makes motors a bit different then a resisitve load when making these calculations.

Get the motor nameplate data then do google for a voltage drop calculator given the wire gauge and current and length and then you can get a pretty exact answer, but my pure guess will still be 14 will work but 12 is better..

Happy New year

John T
 
I have an old trouble light on a windup cord reel, and the wire is no greater than 16 ga, and might even be 18 ga. Obviously only designed for a light source. I hope yours is heavier.

Everybody needs at least one HEAVY drop cord.

Paul
 
Do as you like. But, if the motor gets hot enough due to trying to run on the lower voltage, it will fail prematurely.
 
As long as the motor doesn't draw enough extra current to burn out the windings. As an attempt to compensate for low voltage and/or overload. All will be fine.
In all honesty I can split more wood with less work with an axe than an electric splitter.
Elm of course is another issue.
 
One thing not mentioned is that a lot newer homes are wired with 14 gauge rather than 12. Look on the front of the wall plug to see if its 15 or 20 amp.
Could save you a lot of trouble.
when my nephew rewired my old home he put in all 12 gauge on all wall plugs.
Walt
 
simple easy check this time of year is if it is melted down in the ice/snow after using it it is too light to properly do the job
ron
 
I talked to a local repair man, owns his own portable welding rig ad does all sorts of equipment repairs. Anyway he was tlelling how when he built his shop and ran #6 overhead wire to it and worked fine. One day he noticed that the meter pole was split and had the power co look at it and replace it. At the same time he upgraded his #6 to a much larger wire. His next bills from the power co were $75 dollars a month lower because of the too small wires originally and the welder ran better also, running a welder, lathe, grinder, etc. You get the point it worked with no visible problems but there was sure room for improvement
 
Dan-IA, I don't mean to be a smart alec, but I can't believe you're willing to gamble on the lighter wire. No matter the exact specs, #14 wire is marginal for what you're doing.

Also, have you ever looked inside one of those #14 equipped drop lights? They're pretty chinsy.

I do not use a #14 extension cord for any more than a 100 watt light bulb in my shop. #12 cords may be a bit more clumsy, but are ALWAYS better.

I have never been one to push stuff to the limit.


Glenn F.
 
I don't use any "drop lights" with less than 14 ga. wire. I figure that handles the light and a 3/8" electric drill or the like. All my 110 volt "lead cords" are 12 ga. except one which is 10 ga. I also have a 40 foot 220 volt (3 wire w/G) lead cord for my smallest compressor and the like. Wire is expensive but electric motors are even more costly.
JHMO
 
Like lots have said, 14ga marginal, 12 guage better.

I say I have had 10 trouble lights and when I use them as extension cords I have ALWAYS burnt out or melted the receptical on the trouble light. I don't use trouble lights anymore, too much trouble
 
(quoted from post at 17:35:39 01/02/10)
(quoted from post at 11:47:29 01/02/10) I hear this trotted out at me regularly, an outright accusation that my outdoor extension cords and trouble lights are too light a cord to be running electric motors or battery chargers.

In this particular case I was running my electric log splitter off a trouble light. Between it and the extension cord I think I might be running 40 feet or so of 14ga wire and the electric log splitter runs the motor intermittently (only when the ram is pushing) and it is a 1500W motor on the splitter.

So is there an obvious and simple way to know if I'm overextending my wire? I havent noticed the wire getting warm and don't check voltage drop or anything, if it runs I use it.
Click to expand...
he obvious & simple way is to measure the voltage at the motor to be sure it is within the motor's specified voltage operating range. Done!

Now, your 1500watt motor on 110volts would result in 13.6amps, and 13.6 amps thru 80 feet of 14GA wore (2-way path) will result in 2.7 volts loss or drop in your wire. Typically 5% is maximum allowed for the total circuit, which included both your extension cord & the wiring feeding the receptacle that it is plugged into (some design for 2 or 3 % on motor loads). 2.7/110 X100= 2.4%.
You look OK to me. But remember that I don't know what you have ahead of that receptacle. Motors do have a starting current surge much higher than the run current & it is expected & allowed that the 5% will be exceeded during start up, however, if the start up drop is too great, the motor may not start at all. This is particularly a problem on motors starting while under a load such as some air compressors. In such cases, larger than 'standard practices' wiring may be required. And, finally, a motor which is supplied a lower voltage than designed for, will run hotter than if correctly supplied. If you are fortunate enough to have power delivered to you place at 125volts, then you have more room for loss (voltage drop) than if delivery is 110volts, too.
It is a p!zzer there there are no simple answers isn't it? I guess there sort of is a simple answer: get a big old honkin 10GA wire and over kill the sucker, then your done.
Click to expand...

The problem with your math is that you don't account for lock rotor amps, the starting amps of a motor, which is 5 to 10 times the running amps. Lock rotor amps depends on what the type of motor you are using and what is connected to. If you have a pump or air conditioner and your lights when it starts up, it is because of lock rotor amps. If you get a good amprobe, you can measure LRA and FLA.
 
(quoted from post at 10:24:17 01/03/10)
(quoted from post at 17:35:39 01/02/10)
(quoted from post at 11:47:29 01/02/10) I hear this trotted out at me regularly, an outright accusation that my outdoor extension cords and trouble lights are too light a cord to be running electric motors or battery chargers.

In this particular case I was running my electric log splitter off a trouble light. Between it and the extension cord I think I might be running 40 feet or so of 14ga wire and the electric log splitter runs the motor intermittently (only when the ram is pushing) and it is a 1500W motor on the splitter.

So is there an obvious and simple way to know if I'm overextending my wire? I havent noticed the wire getting warm and don't check voltage drop or anything, if it runs I use it.
Click to expand...
he obvious & simple way is to measure the voltage at the motor to be sure it is within the motor's specified voltage operating range. Done!

Now, your 1500watt motor on 110volts would result in 13.6amps, and 13.6 amps thru 80 feet of 14GA wore (2-way path) will result in 2.7 volts loss or drop in your wire. Typically 5% is maximum allowed for the total circuit, which included both your extension cord & the wiring feeding the receptacle that it is plugged into (some design for 2 or 3 % on motor loads). 2.7/110 X100= 2.4%.
You look OK to me. But remember that I don't know what you have ahead of that receptacle. Motors do have a starting current surge much higher than the run current & it is expected & allowed that the 5% will be exceeded during start up, however, if the start up drop is too great, the motor may not start at all. This is particularly a problem on motors starting while under a load such as some air compressors. In such cases, larger than 'standard practices' wiring may be required. And, finally, a motor which is supplied a lower voltage than designed for, will run hotter than if correctly supplied. If you are fortunate enough to have power delivered to you place at 125volts, then you have more room for loss (voltage drop) than if delivery is 110volts, too.
It is a p!zzer there there are no simple answers isn't it? I guess there sort of is a simple answer: get a big old honkin 10GA wire and over kill the sucker, then your done.
Click to expand...

The problem with your math is that you don't account for lock rotor amps, the starting amps of a motor, which is 5 to 10 times the running amps. Lock rotor amps depends on what the type of motor you are using and what is connected to. If you have a pump or air conditioner and your lights when it starts up, it is because of lock rotor amps. If you get a good amprobe, you can measure LRA and FLA.
Click to expand...
es, a good thought, George, but not a problem. Wire size feeding a motor is never based on LRA or starting surge. Just as an example, we will take a look at a 3 ton condensing unit, with a 50 foot wire run: LRA=76amps, RLA=14amps, specified breaker size=25amps, wire gauge=10.
NOW, if one were to select a breaker and wire size based on LRA/start surge amps of 76, one would install a 90AMP breaker and #2 to #4 gauge wire (depending on specific temperature rating of wire insulation).
Just a little common sense or my favorite "test of reasonableness" would tell a person that virtually the entire Service Entrance capacity (100A) of this little 1100 square foot home would not be consumed by a 36,000BTU air conditioner with wiring equal in size to the Service Entrance wiring.
If still not convinced, go out and look at the name plate data on your condensing unit. No, George, no problem with my math.
Let us take this a step further, with this fellows 1500Watt motor. That 1500w is 13.6 amps at 110 volts. Using your numbers of 5 to 10 times run current for the LRA/start surge, we arrive at 67.5A or 136Amps. IF this fellow were to size his wiring based on your estimated 136 amps, he would need ought or double ought (0 or 00) wiring. IF based on your smaller-end estimate of 67.5A, then he needs the smaller of the two sizes estimated for the air conditioner exercise (#2).
None meets the test of reasonableness. Further more, such an "over-kill" would offer ZERO protection for the wiring in the motor or within the air conditioner condensing unit which would instantly go up in flames when a motor failed and the 90amp breaker allows 90 amps into the units wiring which was designed to be protected by a 25amp breaker.
-----------No, George, no problem with my math.
 
(quoted from post at 18:38:52 01/03/10)
(quoted from post at 10:24:17 01/03/10)
(quoted from post at 17:35:39 01/02/10)
(quoted from post at 11:47:29 01/02/10) I hear this trotted out at me regularly, an outright accusation that my outdoor extension cords and trouble lights are too light a cord to be running electric motors or battery chargers.

In this particular case I was running my electric log splitter off a trouble light. Between it and the extension cord I think I might be running 40 feet or so of 14ga wire and the electric log splitter runs the motor intermittently (only when the ram is pushing) and it is a 1500W motor on the splitter.

So is there an obvious and simple way to know if I'm overextending my wire? I havent noticed the wire getting warm and don't check voltage drop or anything, if it runs I use it.
Click to expand...
he obvious & simple way is to measure the voltage at the motor to be sure it is within the motor's specified voltage operating range. Done!

Now, your 1500watt motor on 110volts would result in 13.6amps, and 13.6 amps thru 80 feet of 14GA wore (2-way path) will result in 2.7 volts loss or drop in your wire. Typically 5% is maximum allowed for the total circuit, which included both your extension cord & the wiring feeding the receptacle that it is plugged into (some design for 2 or 3 % on motor loads). 2.7/110 X100= 2.4%.
You look OK to me. But remember that I don't know what you have ahead of that receptacle. Motors do have a starting current surge much higher than the run current & it is expected & allowed that the 5% will be exceeded during start up, however, if the start up drop is too great, the motor may not start at all. This is particularly a problem on motors starting while under a load such as some air compressors. In such cases, larger than 'standard practices' wiring may be required. And, finally, a motor which is supplied a lower voltage than designed for, will run hotter than if correctly supplied. If you are fortunate enough to have power delivered to you place at 125volts, then you have more room for loss (voltage drop) than if delivery is 110volts, too.
It is a p!zzer there there are no simple answers isn't it? I guess there sort of is a simple answer: get a big old honkin 10GA wire and over kill the sucker, then your done.
Click to expand...

The problem with your math is that you don't account for lock rotor amps, the starting amps of a motor, which is 5 to 10 times the running amps. Lock rotor amps depends on what the type of motor you are using and what is connected to. If you have a pump or air conditioner and your lights when it starts up, it is because of lock rotor amps. If you get a good amprobe, you can measure LRA and FLA.
Click to expand...
es, a good thought, George, but not a problem. Wire size feeding a motor is never based on LRA or starting surge. Just as an example, we will take a look at a 3 ton condensing unit, with a 50 foot wire run: LRA=76amps, RLA=14amps, specified breaker size=25amps, wire gauge=10.
NOW, if one were to select a breaker and wire size based on LRA/start surge amps of 76, one would install a 90AMP breaker and #2 to #4 gauge wire (depending on specific temperature rating of wire insulation).
Just a little common sense or my favorite "test of reasonableness" would tell a person that virtually the entire Service Entrance capacity (100A) of this little 1100 square foot home would not be consumed by a 36,000BTU air conditioner with wiring equal in size to the Service Entrance wiring.
If still not convinced, go out and look at the name plate data on your condensing unit. No, George, no problem with my math.
Let us take this a step further, with this fellows 1500Watt motor. That 1500w is 13.6 amps at 110 volts. Using your numbers of 5 to 10 times run current for the LRA/start surge, we arrive at 67.5A or 136Amps. IF this fellow were to size his wiring based on your estimated 136 amps, he would need ought or double ought (0 or 00) wiring. IF based on your smaller-end estimate of 67.5A, then he needs the smaller of the two sizes estimated for the air conditioner exercise (#2).
None meets the test of reasonableness. Further more, such an "over-kill" would offer ZERO protection for the wiring in the motor or within the air conditioner condensing unit which would instantly go up in flames when a motor failed and the 90amp breaker allows 90 amps into the units wiring which was designed to be protected by a 25amp breaker.
-----------No, George, no problem with my math.
Click to expand...

Look at any breaker, 15 or 20, they can handle around 10,000 a surge. Besides breakers protect just the wire not the motor. I too was an A/C mechanic and have seed many window A/C fried because stupid people tried to use 14awg extension cords to power up an A/C that used less than 1500 watt. And as a retired electronics teacher, I'll give you an A for your math. Keep in mind that LRA causes a voltage drop and impeeds the starting of a motor.
 
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