Due to a yet undiagnosed problem which will not be fixed until some time in the future, I am unexpectedly needing to run 200-300 feet of extension cord, outside along the ground, to a livestock tank heater. Being the safety-conscious guy I am, I’ll be connecting to power at an outlet which powers our pool pump/filter during the summer (so I know it can handle the 1500W draw from the tank heater), which is both away from the house, on its own sub panel, and protected from the elements.

I’m looking on Amazon at long cables for this run and see a 16/3 that says it’s rated at 13A/125V/1625W. That doesn’t seem right to me.

I’m thinking I’m going to go with a 12/3 that indicates 15A/125V/1875W, which makes a lot more sense to me even though it’s quite a bit longer than I need.

Can the numbers on that 16/3 be right, though? There’s another 300ft. 16/3 that is only labeled for 10A/125V/1250W. What games are being played with these very important numbers and how is one to tell (other than by having enough understanding to be skeptical)?

-Rob

Length. 50' or less of 16/3 is rated for 13 amps, while more than 50' is rated for 10 amps. If you are looking at a length longer than 50' and it says 13 amps, then it's mislabeled.

That length of run is only be using a 12/3 extension cord. A 14/3 may work, but for exterior use and length of run I’d want the reassurance from the 12.

I also think that the 16/3 that says it’s rated at 13A/125V/1625W is mislabeled. 16 gauge is undersized and will have too much line drop,especially for the distance that you require.

I'd go with the 12-3 but would verify the recommended gauge of wire for that distance before purchasing.

I’m definitely going with the 12 gauge, but still hoping skins or one of our other master electricians can step in and assure me I’m not going to catch anything on fire with that.

-Rob

Did you say the 12/3 wire you are getting/have is much longer than necessary? 200-300 feet is already a long run... if the cable is significantly longer than that (oof, its a heavy beast, eh?) I'd cut it down to the appropiate length and reattach a high quality connector... and of course install the appropriate connector on the other side of the cut, giving you two working cords of which one of them is the perfect length.

This will increase safety buffer and decrease line drop...

Caveat: I am not an electrician but in a past life did deal with a lot of long runs of power for stage lighting needs (in the pre-LED days)

As a temp. feeder to the tank, I would get a roll of UF (underground feeder) cable. A roll of 12-2 UF. It looks like regular romex that you would use in your house but it is built to be direct buried and is also sunlight resistant if you want to string it up. Comes in 250' rolls.

This may be helpful.
http://www.paigewire.com/pumpW...etectCookieSupport=1

I would hope that one of our licensed electricians will hop on here but in the mean time I would suggest that even 12 gauge wire may not be enough to support 1500 watts over a 300 foot run…

I’m basing this on what we used in our construction projects. We had several 12 gauge 100 foot cords but when you used multiple extension cords together the saws would noticeably struggle to spin up.

My electrician made us a 300 foot 10 gauge extension cord that we used for years without issue…

300 FT is a very long wire run.

I would use this table.

1500 watts is 12.5 amps, I would use 15 amps for a safety figure.

http://wiresizecalculator.net/

10/3 is more suitable for a 300’ run even if it’s only 13A, but if you’re powering a resistive heater and not a motor, the voltage drop at the heater will just result in less heat. OTOH, running a motor in an under voltage condition would not be a good idea if you want to maximize its life.

Remember, it's not just the cords themselves but also the plugs at each end. Most on Amazon or big box stores are made in a third world country and running them at anywhere near rated capacity could have its own problems.

Using Sig2392's online calculator for 300 ft. 15A and 120V open air, it's showing 1/0 AWG with a voltage drop to 118V.

I'd go to an electrical supply house and buy outdoor jacketed wire rated for the length and load over any extension cords. That way not connections/plugs except on the ends.
Afterwards you could sell it locally on something like marketplace to recover much of the cost.

On the other hand it's not clear why you're not just doing the fix now since you said it will be done at some point in the future anyway. The cost, effort, and (safety) risk of this approach of this versus fix it now, is what we don't know and that many might question.

quote:

Originally posted by BurtonRW:
Due to a yet undiagnosed problem which will not be fixed until some time in the future, ...

If you don't mind my asking: Why not just diagnose and fix the problem? The temporary fix you're contemplating is going to cost a lot of money in wire for a temporary fix.

quote:

Originally posted by BurtonRW:
Can the numbers on that 16/3 be right, though?

No.

quote:

Originally posted by BurtonRW:
... how is one to tell (other than by having enough understanding to be skeptical)?

Research. There are on-line calculators all over the place.

quote:

Originally posted by BurtonRW:
I’m definitely going with the 12 gauge, ...

I don't think that's big enough for even 200 feet, much less 300.

quote:

Originally posted by tsmccull:
10/3 is more suitable for a 300’ run even if it’s only 13A, but if you’re powering a resistive heater and not a motor, the voltage drop at the heater will just result in less heat.

This ^^^^^ is what it boils-down to. 10/3 may not even be enough, depending.

Look up the specs on the heater to determine what voltage drop you can tolerate. Measure the source voltage. Go to the Southwire Voltage Drop Calculator. Enter the wire distance as closely as possible (big difference between 200 and 300 feet!), source voltage, maximum percentage of voltage drop you can tolerate, and the true current draw. Click "Calculate" and Bob's yer uncle.

At 125VAC, 15A, with 3% voltage drop (their default) I got 6 AWG for 200 feet and 4 AWG for 300 feet.

I just looked up pricing on 6 AWG wire. $1.58/ft., per-conductor. $1.58 x 3 x 200 = $948.

If you can tolerate an up to 10% voltage drop you can get away with 10 ga. for 300 ft. and 12 ga. for 200 ft.

Perhaps now you can see why: 1. It's important to know exactly what you need and 2. Why it might be wise to just go ahead and fix whatever is the problem?

quote:

Originally posted by 220-9er:
Remember, it's not just the cords themselves but also the plugs at each end.

Yup.

I actually melted the outlet on a light timer, one year, I put so many incandescent outdoor Christmas lights on it. The extension cord was fine, but, the resistance in the outlet connection so high it generated that much heat at the current draw.

Why not just buy a generator for your temp fix?
Better yet fix whatever the issue.
That's a long run that would not excite me for a plethora of reasons.

Is the livestock heater 120v? Can it be run 240v instead?

If you can run it off a 240v outlet, it will draw half the amps as 120v will. This allows you to use smaller wire for the same watts as long as the wire is rated for the voltage.

Of course the safest thing to do is fix the problem that is necessitating the jury rigging.

If you already have wire running from source to load, then why not use that?

300 feet is a long run and will cause a voltage drop at your load (heater) which will limit it's output.

You can use the AC calculator on this page to see the effect of voltage on watts by changing the field labeled 'Voltage' and reading the current below. (I used 10 ohms, 9.6 for the 1500 watt heater and another .4 ohms for 300' of #12 wire):
https://www.rapidtables.com/ca...W%29&bcalc=#calcform

Lowe's has 10/3 cord for $2.90/ft with another $20 to $30 for 5-20p and 5-20r plug and connector bodies.

This message has been edited. Last edited by: Sig Vicious,

BurtonRW I believe you will need a minimum of a 10/3 for your described condition. Distance is too far for a 12/3 at that current to keep your voltage drop to a reasonable value.
Check that you have a commercial recptacle for it to plug into as it will be operating almost continually this winter and a lesser quality recptacle will most likely fail.

Sometimes Amazon descriptions are off.

Don't forget that you will need high amperage outlet. A four-conductor outlet might be best. Custom make the cord. Buy real quality line, on a roll, and install the ends.


When I face problems like this, I often step back and ask "WHAT am I trying to accomplish?" This allows me to separate from the "HOW" to solve the problem before I go down the initial solution idea.


If WHAT you need is a water for livestock, and the tank is 100 yards away...

a. can you relocate the tank to a closer point? Drag it to the pool area, to require a shorter electrical cable.
b. can you use a solar-powered pond surface wiggler like bird baths have to prevent freezing of the water?
c. can you insulate the tank exterior?
d. can you bring hot water to the tank from your garage or home, just enough, to refill the tank? If the tank is not plumbed to refill it there, and you are transporting water with a tractor to the tank, bring hot water.
e. can you use pool water that is already heated with the circulating pump and heater? Hose to relocated livestock tank, siphon from pool to tank, then close exit valve. Obviously bad if salt water pool, but maybe low chlorine level wouldn't hurt animals? I have no idea...I am a city dweller.


Sounds like your existing electrical circuit to the livestock tank is defective for unknown reasons. Maybe a subsurface current detector could find the break quickly.

quote:

Originally posted by tsmccull:
10/3 is more suitable for a 300’ run even if it’s only 13A, but if you’re powering a resistive heater and not a motor, the voltage drop at the heater will just result in less heat. OTOH, running a motor in an under voltage condition would not be a good idea if you want to maximize its life.

This , in a nutshell .

Burton - Not sure this will help you but this was on the back of an extension cord I purchased earlier this year..