*Question E4E14:
What is the purpose of a single point ground panel?*  

*Correct Answer is  D: Ensure all lightning protectors activate at the same time*  

### AI Response: (may contain errors)  

A single point ground panel is an important component in radio installations, particularly for lightning protection and minimizing interference. 

### Correct Answer: D - Ensure all lightning protectors activate at the same time

- **Explanation**: A single point ground panel is designed to provide a common grounding point for all equipment and lightning protection devices. This ensures that in the event of a lightning strike, all protectors will activate simultaneously, directing the surge to ground and minimizing the risk of damage to equipment. By having a single grounding point, you reduce the potential for ground loops and ensure that all devices are at the same electrical potential.

### Why the Other Choices are Incorrect:

- **A: Remove AC power in case of a short-circuit**  
  - This is not the primary function of a single point ground panel. While grounding can help in safety by providing a path for fault currents, the panel itself does not remove AC power; that is typically handled by circuit breakers or fuses.

- **B: Prevent common-mode transients in multi-wire systems**  
  - While grounding can help reduce common-mode noise, the primary purpose of a single point ground panel is not specifically to prevent common-mode transients. It is more about providing a unified grounding point for lightning protection.

- **C: Eliminate air gaps between protected and non-protected circuits**  
  - A single point ground panel does not eliminate air gaps; rather, it ensures that all circuits are referenced to the same ground potential. Air gaps are physical separations and are not directly addressed by grounding practices.

### Useful Rules of Thumb:

- **Grounding**: Always ensure that all equipment is grounded to a single point to minimize potential differences and reduce the risk of damage from surges.
- **Lightning Protection**: Use a common ground for all lightning protection devices to ensure they operate effectively during a surge event.

By understanding the purpose of a single point ground panel and its role in lightning protection, you can better prepare for questions related to grounding and safety in the Extra Class exam.