All of the following can increase circuit resistance EXCEPT:

• A. Short to ground in the circuit
• B. Increased conductor length
• C. Lower quality conductor material
• D. Thickness of wire insulation

Answer: (D)

Resistance is determined by the material’s resistivity, the conductor’s length, and its cross-sectional area. If you lengthen the conductor, electrons have to travel farther, so resistance goes up. Using a material with higher resistivity makes it harder for electrons to flow, increasing resistance as well. A short to ground creates a path of very low resistance to ground, which tends to lower the overall resistance seen by the source and can cause high current—so it doesn’t increase resistance. The thickness of the wire’s insulation does not change the conductor’s resistance (it doesn’t affect resistivity, length, or cross-sectional area); it mainly influences how much heat the wire can safely handle and its voltage rating. Therefore, insulation thickness is the factor that does not increase circuit resistance.