Allowable voltage drop is not just a bureaucratic number; it is a measure of system health. Sticking to the and 5% for total systems ensures that your equipment runs efficiently, lasts longer, and operates safely.
If you have a 120V circuit and you calculate a drop of 3.6V: $$ (3.6 / 120) \times 100 = 3% $$ This is right on the limit of allowable drop.
The term "allowable" isn't just a rule of thumb; it is defined by electrical codes and standards. While specific regulations vary by region, the industry standard rule of thumb is:
Think of voltage as water pressure in a hose. As water travels through a long, narrow hose, friction against the walls reduces the pressure at the end of the line. Electricity behaves similarly.