NCCER Electrical Certification Practice Test

The wattage output of series resistance heating cables is fundamentally linked to the amount of resistance in the circuit. Specifically, the relationship between voltage, current, and resistance in a circuit is described by Ohm's Law, where voltage equals current times resistance (V = I × R). Consequently, for a given voltage, the wattage (power) is calculated using the formula P = V × I. Since the current is determined by the total resistance and the applied voltage, any change in the resistance of the heating cable directly impacts the wattage output.

In terms of heating cables, as the length of the cable increases, the resistance increases proportionally. Therefore, for a set voltage, the resulting current will be lower with greater resistance, which in turn reduces the power output. This demonstrates that resistance plays a crucial role in defining how much power the heating cables can produce, confirming that it is critical in determining wattage output in addition to the total circuit length.