Which statement best describes the potential danger of small currents if sustained?

• A. Even currents as low as 20 mA can cause significant damage or be fatal if sustained for a period.
• B. Small currents are always harmless regardless of duration.
• C. Only high currents are dangerous, regardless of duration.
• D. Sustained currents never cause damage at low levels.

Answer: (A)

Even small electrical currents can be dangerous if they flow through the body for a sustained period. Currents around 20 milliamperes are enough, with duration, to cause strong muscle contractions that can trap you against the source and, if the current travels through the chest, disturb the heart’s rhythm. Over time, energy delivered to tissues accumulates (I^2R heating), increasing the risk of burns and internal damage. This is why sustained low currents aren’t safe—the danger isn’t just about how large the current is, but also how long it lasts and where it passes through the body.