What is a typical voltage drop limit cited in codes for branch circuits?

What is a typical voltage drop limit cited in codes for branch circuits?

• A. 1%
• B. 2%
• C. 3%
• D. 10%

Answer: (C)

Voltage drop is the loss of voltage that occurs as current flows through conductors due to their resistance. Codes set practical limits to keep the voltage at the farthest outlet within an acceptable range. For branch circuits, the typical limit is 3%. This means the load at the far end should see voltage within about 3% of the supply (roughly 3.6 V on a 120 V circuit or about 7.2 V on a 240 V circuit). Keeping to this 3% helps prevent devices from underperforming (dim lights, motors running slow, or electronics behaving oddly). If the drop is higher, you’d either use larger conductors, shorten the run, or change routing to reduce resistance. Note that total system voltage drop (from service entrance to load) is often discussed as a separate consideration, commonly around 5%, but the branch-circuit limit itself is typically 3%.

Voltage drop is the loss of voltage that occurs as current flows through conductors due to their resistance. Codes set practical limits to keep the voltage at the farthest outlet within an acceptable range. For branch circuits, the typical limit is 3%. This means the load at the far end should see voltage within about 3% of the supply (roughly 3.6 V on a 120 V circuit or about 7.2 V on a 240 V circuit).

Keeping to this 3% helps prevent devices from underperforming (dim lights, motors running slow, or electronics behaving oddly). If the drop is higher, you’d either use larger conductors, shorten the run, or change routing to reduce resistance. Note that total system voltage drop (from service entrance to load) is often discussed as a separate consideration, commonly around 5%, but the branch-circuit limit itself is typically 3%.