If it is 50W then the current is 50W/230V = 0.217A or 50W/120V = 0.417A, according to the voltage.
The current rating is not likely to be an issue, but the voltage drop could be..
For a 5% voltage drop the resistance is:
R = V/I = 6V/0.417A = 14.34 ohms for the 120V situation.
R = V/I = 11.5V/0.217A = 53 ohms for the 230V situation.
The length is 3000 feet (call it 1km, though actually 914.4 metres). The smallest copper wire size for the 120V situation is then 16 AWG (18A rated), while for 230V it is 22 AWG. I have not taken into account the wire temperature, but the extra length might compensate.
The cable is chosen according to the temperature and the environment it will be in, for example sunlight and rain needs conduit most likely. Being behind insulation like a wall, or in a hot roof space needs higher temperature (75°C). Therefore you should use appropriate house wiring cable and comply with regulations. The 22AWG size is all that is needed for the 230V situation according to voltage drop, but a larger size is required to meet the physical requirements, so you could say 16AWG too. It will just have less voltage drop and work better. The cable needs to be protected by a circuit breaker of less than its current rating (amps).The circuit breaker is 8A or less so it can trip with a short circuit at the far end of the cable in the 120V situation.
Best to get an electrician to do this.
Yes, you could use long 1500 feet long wire. But it could drop about 20V or more depending on the wire size, therefore, a small size 40W step up transformer is needed to compensate this loss.
Obtain a 120 : 140V small transformer, feed 140V via 1500 feet wire. At the end of wire with 40W load, voltage would be 120V.
Make sure you buy 12 gauge wire in those extension cords for that long of a distance.
My son used extension cords to his tree house which had lights, stereo and a mini refrigerator, (maybe 500 watts top), and he ran about a 600 ft extension cords and had no problem, but it was the heavier duty extension cords
depends on the voltage , the higher the voltage the easier it is, if it's 120 volts then 40 watts is only 1/3 of an amp so any heavy gauge cable will do , you can buy 500yd drums , better than dozens of plugs and sockets
If you need 120 volts, wire the circuit for 220 and use resistors to modulate it down to 120. You may only have 190 volts left at that distance but you would have to measure it to calculate the resistor you need.
About 1500 ft. I only will need to use about 40w for a long period of time. Can I use extension chords? Money is not an issue. No generators.
