*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)  

The correct answer to the question about high voltages that produce RF burns is:

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

### Explanation of the Correct Answer:
- **High Impedance Ground Wire**: When the ground wire has high impedance at a specific frequency, it can prevent effective grounding. This means that RF currents can build up on the ground wire, leading to high voltages. These high voltages can cause RF burns if a person comes into contact with the wire or equipment connected to it.

### Why the Other Choices are Incorrect:
- **A: Flat braid rather than round wire has been used for the ground wire**: 
  - While flat braid can have different characteristics compared to round wire, the primary concern for RF grounding is not the shape but the overall impedance and conductivity. Flat braid can be effective if properly sized and installed.

- **B: Insulated wire has been used for the ground wire**: 
  - Using insulated wire for a ground connection is not appropriate because it prevents the wire from effectively grounding. However, this choice does not directly relate to producing high voltages; rather, it would simply fail to provide a good ground.

- **C: The ground rod is resonant**: 
  - A resonant ground rod can affect the performance of an antenna system, but it does not directly cause high voltages that lead to RF burns. Resonance may lead to inefficiencies or other issues, but it does not inherently create high voltages on the ground wire.

### Useful Concepts:
- **Impedance**: The impedance of a ground wire can vary with frequency. At certain frequencies, if the impedance is high, it can lead to voltage buildup.
- **Grounding**: Effective grounding is crucial in RF systems to ensure safety and proper operation. A low-impedance ground connection is essential to prevent RF currents from causing high voltages.

In summary, the key takeaway is that high impedance in the ground wire at RF frequencies can lead to dangerous voltage levels, making option D the correct answer.