Help a girl with her electricity please?

[Timelord]

If the distance of cable is short, then voltage drop is not as bad. On transmission networks - High voltage is 11000volts up. Medium voltage is 415v up to high and below that is not on the transmission network as it is by now in the consumer premises. High voltage is used on national transmission and local transmission networks due to the voltage drop issues and in that it is far more efficient to transmit electricity along long wires at these voltages. Step down transformers are used to drop the voltage successively until it reaches the customers premises. 230Volts is used in domestic premises as it is still high enough to overcome voltage drops efficiently - as Skvez says. Running "white goods" type equipment is not very efficient on a 12volt system. If you are having design problems, you could try two further options.
1) rig the wiring system up as a 24volt circuit from a multiple battery, with a voltage drop unit to 12 volts at the connection of each item of 12volt equipment. That will help with the voltage drop problem to some degree.
2) to avoid purchasing expensive thicker cable, you could double the number of cables, ie. run two cables instead of one to each unit. This is not as neat but will provide more cross sectional area of wire for the current to pass along. Although doubling the cable runs does on the face of it increase the cost of purchasing the wiring, thinner cabling can be sourced more easily at cheaper prices and bigger cable reels are pro rata cheaper than smaller cable reels to buy. Try non ferrous scrap metal yards. They often have whole or substantial rolls left over from customers trade jobs - going very cheap or ebay or gumtree etc. Regards, TL