You've got a good grasp of the situation and a reasonable approach. Let's break down your interpretation and add some points for consideration

Your Interpretation - Correct with Clarifications:
NEC 810 Applicability

You're correct. While the Starlink dish itself is plastic, the electronics inside and the fact it's connected to the electrical system through the PoE connection puts it under the umbrella of NEC 810.

Outdoor Surge Protector

Excellent idea to install a gas discharge surge protector at the base of the mast on the CAT5/6 cable before it enters the home. This is crucial to shunt surges to ground at the mast. Ensure the surge protector is properly rated for outdoor use and connected to the grounding system.

Service Entrance Ground Extension

This is the core of the issue, and your approach is generally correct. You're essentially creating a low-impedance path to ground.

NEC 810 and Grounding Requirements (Key Considerations)



NEC 810.21(F) Grounding Conductors

This section is critical. It outlines the requirements for the size and material of the grounding conductor. It states: "The grounding conductor shall be copper, aluminum, copper-clad steel, bronze, or other corrosion-resistant conductive material." "The grounding conductor shall be as short as practicable and shall be run in a straight line where possible."

For masts or structures exceeding 50 feet (15.2 m) in height, the grounding conductor shall be sized in accordance with Table 810.16(A) for antenna conductors. This is unlikely to apply to your 15ft mast, but it's worth double-checking. NEC 810.21(J) Bonding of Electrodes

You're correctly thinking about bonding. The NEC requires all grounding electrodes present to be bonded together to form a single grounding system. This includes: The grounding electrode system at your service entrance. Any supplemental ground rods you install at the mast. Any other metal objects on the roof that could become energized in a lightning strike.

Your Specific Plan - Refinement and Best Practices


Ground Rods at Mast



Number of Rods

While one ground rod might meet minimum code,

two ground rods spaced at least 8 feet apart are highly recommended. This drastically reduces the impedance of the grounding system. Multiple grounding electrodes are always better than one. Aim for a soil resistance of 25 ohms or less. Ground Rod Type

Use copper-clad steel ground rods that are at least 8 feet long. Longer rods are beneficial if your soil is dry or rocky.

Driving Rods

Drive the rods completely into the ground (if possible) or bury them horizontally if rock prevents vertical driving.

Inspection

After driving the rods, it's a good idea to have them inspected by a qualified electrician to ensure they meet local code requirements and soil resistance is appropriate.2.

Connecting to Service Entrance Ground



Conductor Size



#6 AWG copper is a minimum, but larger is better, especially for lightning protection. #4 AWG or even #2 AWG would provide a lower impedance path. The increase in cost is relatively small compared to the overall protection offered. Material

Use copper. While aluminum is sometimes permitted, copper is a better conductor and more corrosion-resistant in buried applications.

Method



Direct Burial

Direct burial is common. Use a UF (Underground Feeder) rated cable. Bury it deep enough to avoid damage from gardening or other activities (check local code for minimum burial depth – typically 12-18 inches).

Conduit

Running the conductor in conduit (PVC or metal) offers the best protection against physical damage and corrosion, but it adds to the cost and labor.

Connections

Use approved direct-burial connectors or exothermic welds (Cadweld) for connecting the ground wire to the ground rods and the service entrance ground. Avoid mechanical clamps that can loosen or corrode over time. Coat connections with an anti-corrosion compound.

Straightest Path

Run the grounding conductor in the straightest, shortest route possible. Avoid sharp bends.

Ground Rod Spacing along the Run

Your plan to add ground rods every 20 feet or less is good. This reduces the impedance of the long run back to the service entrance ground. Each of these rods must be bonded to the #6 AWG (or larger) conductor connecting the mast's ground rods to the service entrance ground.3.

Bonding to Other Metal



Crucial

If there are any other metallic objects on the roof (e.g., gutters, metal vent pipes, satellite dishes), they must be bonded to the grounding system as well. This prevents flashover between these objects during a lightning strike. Use #6 AWG copper or larger for these bonding connections.

Example

If you have metal gutters running near the mast, bond the mast's grounding system to the gutter system.4.

Home Entry Point



Grounding at Entry

Consider adding a secondary grounding point where the CAT5/6 cable enters the house. This can be a ground rod driven near the entry point and bonded to the service entrance ground (again, with #6 AWG or larger). Connect the surge protector's ground wire to this local ground point.

Second Surge Protector (Optional)

Consider a second surge protector inside the house, near the device connected to the PoE injector. This provides an additional layer of protection.5.

Professional Consultation



Highly Recommended

Given the importance of proper grounding and the potential for damage from lightning strikes, it's strongly recommended to consult with a qualified electrician or lightning protection specialist. They can assess your specific situation, ensure compliance with all applicable codes, and provide recommendations tailored to your needs.

Key Considerations and Cautions



Lightning is unpredictable

No grounding system guarantees 100% protection from a direct lightning strike. The goal is to minimize the risk of damage and injury.

Impedance, not just Resistance

Think about impedance, not just resistance. Impedance is the AC equivalent of resistance and is what really matters at high frequencies (like those associated with lightning). Short, direct runs of large-diameter conductors are essential for minimizing impedance.

UL Listing/Certification

Use only UL-listed or otherwise certified components for all grounding and surge protection elements.

Local Codes

Always check and comply with all local electrical codes. They may have specific requirements that differ from the NEC.*

Soil Conditions

Soil conductivity varies greatly. Sandy soil is less conductive than clay soil. Dry soil is less conductive than moist soil. This affects the effectiveness of ground rods.

In summary: Your plan is a solid starting point. Adding more ground rods, using larger gauge wire, and bonding to other metal objects will significantly improve the effectiveness of your grounding system. Consulting with a qualified electrician is highly recommended to ensure safety and compliance with all applicable codes. Remember, a well-designed and properly installed grounding system is a critical investment in protecting your home and equipment. Flag for review