*Question T0B08:
Which is a proper grounding method for a tower?*  

*Correct Answer is  D: Separate eight-foot ground rods for each tower leg, bonded to the tower and each other*  

### AI Response: (may contain errors)  

To determine the proper grounding method for a tower, let's analyze the choices provided.

### Correct Answer: 
**D: Separate eight-foot ground rods for each tower leg, bonded to the tower and each other.**

#### Explanation:
- **Multiple Ground Rods**: Using separate ground rods for each leg of the tower ensures that the grounding system can effectively dissipate lightning strikes and RF energy. 
- **Bonding**: Bonding the ground rods together and to the tower creates a low-resistance path to ground, which is crucial for safety and performance.
- **Depth**: Eight-foot ground rods are standard because they provide a good connection to the earth, which is essential for effective grounding.

### Why the Other Choices are Incorrect:

- **A: A single four-foot ground rod, driven into the ground no more than 12 inches from the base**  
  - **Issue**: A single four-foot ground rod may not provide sufficient grounding. The depth is inadequate for effective grounding, especially in areas with high soil resistivity. A single rod can also create a high-resistance path, which is not ideal for lightning protection.

- **B: A ferrite-core RF choke connected between the tower and ground**  
  - **Issue**: While RF chokes can help reduce RF interference, they do not serve as a grounding method. Grounding is about providing a safe path for electrical surges, while RF chokes are used to block unwanted RF signals.

- **C: A connection between the tower base and a cold water pipe**  
  - **Issue**: While connecting to a cold water pipe can provide a grounding path, it is not a reliable method. Water pipes can be insulated or disconnected, and local codes may not allow this as a primary grounding method. Additionally, it may not provide the low-resistance path needed for effective lightning protection.

### Useful Rules of Thumb:
- **Ground Rod Length**: Use at least eight-foot ground rods for effective grounding.
- **Bonding**: Always bond multiple ground rods together to ensure a low-resistance path.
- **Separation**: For towers with multiple legs, use separate ground rods for each leg to enhance safety and performance.

By following these guidelines, you can ensure a proper grounding method for your tower, which is essential for both safety and effective operation.