12v wire v 240 v wire

What you have discovered is correct, I've used three core extension leads to connect things like camp lights, dash mounted winch controls and the like.
But they won't carry appreciable amounts of current and are quite often too stiff to survive in an automotive application for an extended period.
Wire designed to be installed in a fixed building application (house wiring) will break prematurely due to having a small number of thick wires as opposed to good automotive wire which is composed of many fine strands which make the cable flexible and able to survive in a mobile application.
Then there is the different insulation ratings of the plastic sheath etc.

Hi

The insulation is designed and manufactured to Australian Standards for cables to be rated for 240V AC use.

Auto 12 volt DC cable is multi stranded copper to ensure greater flexibility so that it can withstand constant vibrations. Quality auto cable has different insulation standards depending on the proposed use of the cable.

All current flow is measured in amps (amperes). Water equivalent is litres of water.

All voltage is measured in volts. Water equivalent is pressure.

A simple way of looking at it is, the higher the volts (pressure of water) the more current flow (litres of water) through the same size cable (water pipe). BUT the comparison of electricity to water doesn't work past the examples above.

In simple terms the current carrying capacity of the cable is determined by the cross sectional area of the copper, the larger the cross sectional area the more amps can be efficiently transmitted. However, multi stranded cables can carry a little more current than solid copper of the same cross sectional area.

The longer the cable the greater the voltage drop for the same cross sectional area of copper. Voltage drop may result in greater current flow and heat loss which all adds up to inefficiency and possible failure of the circuit.

Hope you can understand my carrying on
Cheers
Phil

Moose

As others have said, 240v cable will carry low voltage direct current up to its AMPS rating - generally about 10. Even that much will start to waste power, which you don't have a lot of to throw away. But for a small light etc no worries.

BUT - AND I AM YELLING BECAUSE ITS IMPORTANT (and I am a bad teacher) - MAKE SURE YOU CAN NEVER PUT 240 VOLTS IN ONE END AND CONNECT IT TO A 12 VOLT APPLIANCE AT THE OTHER.

By that, I mean - put 12 volt type plugs both ends - don't take the "logical" step of using three pin plugs because they are easy to use and you reckon you will remember. The least that would happen is you fry the light or what ever, the worst is someone will die. In between you could cook the car's electrics.

Safety is the worry with electricity when you don't have a good understanding.

Max

Cables have a voltage rating which is relevant to their ability to insulate that voltage.

ie. electrical energy will always try to "go home" - the active line will try to feed current to the neutral line and it will jump across any barrier to do that if it possibly can - including through cable insulation if it's not strong enough. If you have a electrical system with a 500,000 volt supply it will jump some distance across air (it will "arc").

Voltage ratings describe the ability of cable to stop that arcing - for 12V a piece of paper will do the job, for 240V we need something more serious for 10,000V more serious still.

As an end user the only thing you really need to know is that you should _NEVER_, _EVER_, _UNDER ANY CIRCUMSTANCES_ use cable which is rated to a voltage lower than you intend to apply to it - so 12V car cable used for 240V is a big NO NO.

Mike Harding