*Question G4C05:
What is a possible cause of high voltages that produce RF burns?*  

*Correct Answer is  D: The ground wire has high impedance on that frequency*  

### AI Response: (may contain errors)  

High voltages that produce RF burns are often caused by high impedance in the ground wire at a specific frequency. Let's break down the options:

1. **Correct Answer: D: The ground wire has high impedance on that frequency**

   - **Explanation**: At certain frequencies, a ground wire can exhibit high impedance due to its length being a significant fraction of the wavelength. This high impedance can cause voltage to build up along the wire, leading to RF burns if touched. The impedance of a wire is frequency-dependent and can be calculated using the formula for inductive reactance:
     $$X_L = 2\pi f L$$
     where:
     - $X_L$ = inductive reactance
     - $f$ = frequency
     - $L$ = inductance of the wire

2. **Why the other choices are incorrect:**

   - **A: Flat braid rather than round wire has been used for the ground wire**
     - Flat braid is often used for grounding because it has a lower inductance and can handle high currents better than round wire. It is unlikely to cause high impedance at RF frequencies.

   - **B: Insulated wire has been used for the ground wire**
     - Insulation does not affect the impedance of the wire at RF frequencies. The impedance is more related to the wire's length and the frequency of the RF signal.

   - **C: The ground rod is resonant**
     - Ground rods are typically too short to be resonant at HF frequencies. Resonance is more of a concern with longer conductors, like the ground wire itself, rather than the ground rod.

Understanding these concepts helps in diagnosing and preventing RF burns by ensuring that ground wires are appropriately designed and installed to minimize impedance at operating frequencies.