Which of the following factors does not tend to increase impedances?

• A. Broken/faulty wires
• B. Dirty electrodes
• C. Increased site preparation
• D. Poor application

Answer: (C)

Understanding impedance at the skin–electrode interface is key. Anything that worsens contact between skin and electrode raises impedance: broken or faulty wires can interrupt the circuit; dirty electrodes add resistance from oils and contaminants; and poor application creates air gaps or poor adhesion. When site preparation is increased and done properly, it actually improves the contact—removing oils and dead skin and often using conductive gel—so the skin–electrode path conducts more easily and impedance drops. So the factor that does not tend to increase impedances is increased site preparation, because it enhances contact rather than degrading it.