EBay seller selling fake LED's (non functional).

[sleemanj]

According to the info at that page, i need 16 gauge wire for power? That can't be right, that's an awfully beefy cable for a basic LED!

You can pretty much ignore the power transmission number, that's when you are generally talking about a wiring bundle (eg, the flex inside your walls, 2/3 wires inside a common insulation) and as such the heat dissipation is significantly reduced.  It's also very conservative.

3A over 22AWG should be fine.

It's all about the power dissipation.  If the wire is not getting noticeably hot running at full load, and it's not dropping too many volts for you, then no worries.

[RobFromEarth]

Ok, thanks, i wasn't sure if it meant just for wire over a given length or something else. But doesn't voltage play a part also? i.e. a cable may be able to safely pass I amps at E volts, but if volts goes too much higher, don't you need a thicker cable, or it it strictly the current that dictates the gauge needed?

[sleemanj]

But doesn't voltage play a part also?

The wire only "knows" about itself, and what it "knows" is exactly what you know, that it has a resistance, and that it's passing a current. 

The voltage that the wire drops is defined therefore by Ohm's Law.

V=IR

You know I - the current you are passing (3A),
You know R the resistance of your wire (whatever it is, measure if you like),
Thus you calculate V, that being the voltage difference between one end of the wire and the other.

Voltage is a consideration in wire only in so far as insulation - high voltages can pierce insulation and establish a spark to lower potential things.

[RobFromEarth]

That's pretty clear, just think of the wire as a resistor and use basic ohms law, that makes sense now, thank you. Really basic stuff, i don't blame some people for being irritated, thanks for the explanation.