I need to run an electical extension cord anywhere between 250 to 350 feet to run a mini dorm refrig, a light and radio. I will connect it to a outlet in my house which is that far away. Any ideas if this is possible and what type of cord I would need.

Thanks a bunch for any help.

Rupert Negley

You actually will most likely run into a problem with the power consistency running an extension cord that far. I am not an expert on the physics of the situation I do know that many appliance manufacturers warn you to only use extensions of feet or less. You would be much better off going to your local hardware and just buying some electrical cable to attach to the outlet at the house and run it out to the area where you need the plug ins. This is not difficult to do. Shut off the breaker to that outlet and then connect one endo f the cable to the appropriate connections on the outlet. attach a plug in outlet to the other end and an electrical housing box to hold this outlet and then either attach the cable to a building or poles that run out to the area where you want it. Pay attention to height and placement so that you are not running things into this cable.. It is never a good idea to run it on the ground or where it can be run into by equipment or humans. You can actually get information, advice and all the parts at the home Depot or Lowe's Hardware, or Ace Hardware, etc. and this is probably about a 2 hour project even for an inexperienced person unless you have nothing in place to run the cable along out to the area you want it.

KeepItSimpleStupid

Portable cord has different designations. Your best to use 12 Ga. Use an angle plug or replace the receptacle with a twist lock if you can because they don't fall out.

Portable cord - Wikipedia, the free encyclopedia

You need S and W

The 12/3 SOOW from the link below would be fine.

http://www.brimelectronics.com/PORTcable.htm

The company is great for price, not for delivery. They are a manufacturer, but with that kind of put up they should be able to accomodate. You just have to wait until they do the stuff you want.

AndersonZ

In order to run an extension to supply constant uninterupted power that distance, it would require a bit of calculation using the formula (2*k*I*L)/CM.

For this instance, to run a cable copper cable (13 constant [k]) 350 feet, at 15A, and 120V, with an allowable voltage drop of 3.6 volts (NEC 2008), you would calculate this as (2*13*15*350)/3.6 = 37917 CM requirement to supply constant power that distance.

But ... simply stated, you would need a 4GA wire THWN insulation type, rated for indoor/outdoor use (I assume this is outdoor, so THWN rating)

KeepItSimpleStupid

And similarly a 14 AWG extension cord at 350 feet with a 1.2 AMP CONTINUOUS load would have a 2.2 % drop and would be fine. Refrigerators are not a continuous load anyway.

And to make matters really interesting, suppose we put a 12 to 480 step up xformer at the source and stepped it down to 120 at the destination. Check me on my calcs: that's 10 Amps of 120 V that can be continuous using 12 AWG wire.

THWN wire is unprotected so cannot be used.

Again, without a decent handle on the loads, we can't determine anything.

AndersonZ

The voltage drop at the end of any length of cable cannot be more 3% of the branch circuit voltage. A 14 AWG extension would have a large voltage drop, which would not supply sufficient power to power a light, radio, and refrigerator, regardless of the load being continuous or not. The allowable voltage drop on any branch circuit is 3%, and 3% of 120v is 3.6V, so at the end of the extension, if you measured the voltage it must be 116.4.

With a 14 AWG extension cord, connected to an outlet at the front of the house (which I am assuming is on a 15 breaker or fuse), run 350 feet, the voltage drop would be 33.21 volts, therefore at the end of the 350 ft, you would only be recieving roughly 86.71volts.

By increasing the circular mill area of the wire, it reduces the overall resistance of the run, which in turn decreases the voltage drop.

Not to be a bullheaded, but I still stand by my answer of a 4 AWG cable to supply electricity at that distance.

KeepItSimpleStupid

The load isn't 15 amps. So put an external breaker for 2 amps.

AndersonZ

Yea, I was driving home and it hit me, must have had a brain fart.