The usefulness of sense wires at higher voltages seems kind of counter-intuitive, because normally higher voltages are accompanied by lower currents (assuming the power is constant), which result in less voltage drop and less loss. But higher voltages permit greater voltage drops to achieve the same amount of loss. For example, a 2% drop at 24v is a 0.48v, while at 48v it's 0.96v. A wire at 24v carrying 30a (720w) with a 2% voltage drop will lose 14.4w and have a resistance of 0.016 ohm. A wire at 48v carrying 15a (720w) with a 2% voltage drop will lose 14.4w and have a resistance of 0.064 ohm. Same power loss, but you're allowed to use a wire that has four times the resistance. So the tendency with higher voltages is to use smaller, less expensive wire (or longer distance) to achieve the same loss as a lesser voltage with a larger wire (or shorter distance)...but the result is a larger voltage drop, which makes sense wires more useful. Of course, if you use the same gauge wire in both instances, your loss goes down with higher voltage and so does the voltage drop.
