Wire Gauge Required Question
For some reason I just can't understand the various wire gauge tables, and I have tried to, so I am hoping somebody will take pity and do all the work! :) One table that I can follow says that for...
Forum Discussion
lorelec wrote:
We have to remember when we're talking about power loss through a wire (or resistor) that it's the voltage drop *across* the wire (or resistor) that produces the power loss. If we have 1 volt at one end of the wire, and 0.98 volt at the other end, that's a 0.02 volt drop => a 2% drop in voltage, which becomes a 0.0004w loss ((0.02)^2 / 1) across a 1 ohm resistance. To produce a 0.02v drop across a 1 ohm resistance, there must be 0.02amp of current flowing through it (0.02 / 1), which means that we have 0.02w of power available. A 0.0004w loss out of 0.02w is 2% (0.0004 / 0.02). So a 2% voltage drop across the wire results in a 2% power loss in the wire...
What???
:?
We are talking about a 2% change of the voltage across the resistor, not a 2% (of some unknown reference value to compare against) voltage drop...
A 2% reduction of voltage across a resistor results in a 2% reduction of current through the resistor which is a 4% reduction in power lost...
