An extension cord is to be used with a portable electric fan heater. The manufacturers warn against using extension cords. However, if one must be used, they recommend the current should never exceed 3.20 A. Determine the maximum root-mean-square current that can be safely passed through the extension chord.

• A. 1.45 A
• B. 4.46 A
• C. 6.81 A
• D. 2.26 A

Answer: (D)