You're asking about a very specific application of grounding electrode systems, and unfortunately, the NEC and IEEE standards don't provide explicitly defined distances for grounding rods in a triangular configuration nor specific clearances between a triangular grounding rod configuration and generator sets. However, we can find guidance and applicable rules that will inform best practices and compliant installations.Here's a breakdown of relevant NEC and IEEE provisions, along with explanations to guide you

1. Grounding Electrode Spacing (General Principles - Applicable to Any Configuration):
NEC 250.53(B): Supplemental Electrode Required. This is the most relevant section. While it doesn't specify a distance between electrodes in a triangular configuration, it implicitly governs spacing. It mandates a supplemental grounding electrode (like a second rod) if a single rod has a resistance to earth exceeding 25 ohms. NEC 250.56: Earth Electrode Resistance. If you have concerns that a single grounding electrode will exceed 25 Ohms to ground, testing is required to verify that the impedance to ground is less than 25 Ohms. If your single grounding electrode (rod, plate, etc.) measures over 25 ohms to ground, you are required to install a supplemental grounding electrode (such as a second ground rod) in accordance with 250.53(B). Crucially, NEC 250.53(B) mandates a minimum separation. The supplemental electrode must be separated by not less than 6 ft (1.83 m) from any other electrode of the grounding electrode system. Why this matters for Triangular Configuration

While not directly addressing a triangle, the minimum 6 ft separation is essential. If you use a triangular arrangement, all three points of the triangle must be at least 6 ft apart from each other. This is because each of the rods is considered part of the grounding electrode system.

IEEE Std 142-2007 (Green Book)

While not legally binding like the NEC, the Green Book provides recommended practices for grounding. Look at section 4.2.
4.1 (Spacing of ground rods): It often recommends spacing ground rods at least equal to their driven depth. For example, an 8-foot ground rod would then optimally be at least 8 feet apart from another ground rod. This is to ensure that each rod effectively dissipates fault current and that their "zones of influence" don't overlap excessively, reducing overall effectiveness. The IEEE Green Book does not specifically address triangular configurations. Remember: The IEEE Green Book is an advisory document, not a legal requirement unless specifically adopted by your jurisdiction.

2. Distance Between Grounding Electrode System and Genset



NEC Doesn't Directly Specify Distance

The NEC doesn't provide a specific minimum distance between a grounding electrode system (including rods) and a generator set. It focuses on ensuring proper bonding and grounding connections.

NEC 250.30(A)(6): Grounding Electrode System. For separately derived systems (like generators), this requires connecting to the nearest available grounding electrode or grounding electrode system. This doesn't mandate a distance, but emphasizes connecting to the existing system. NEC 250.34: Portable and Vehicle-Mounted Generators. This section covers grounding requirements for portable generators. It also does not specify a distance requirement. Focus on Bonding and Grounding Conductors (GECs)

The key is to have a properly sized and installed Grounding Electrode Conductor (GEC) connecting the generator's neutral (in separately derived systems) or frame (in non-separately derived systems) to the grounding electrode system. The GEC's size is determined by NEC Table 250.66. The shorter and straighter the GEC, the better.

Practical Considerations and Best Practices



Proximity for Efficiency

Placing the grounding electrode system relatively close to the generator (within a reasonable distance, say 20-30 feet) can minimize the length of the GEC, reducing impedance and improving grounding effectiveness. Shorter is generally better for the GEC.

Safety and Maintenance

Ensure that the location of the ground rods doesn't create a tripping hazard or interfere with access for maintenance of the generator.

Soil Conditions

The grounding electrode system should be located in an area with good soil conductivity.

In Summary: For Your Triangular Grounding Rod Configuration and Genset Installation


Minimum Spacing

Ensure at least 6 feet between each grounding rod in your triangular configuration (based on NEC 250.53(B)). IEEE Std 142-2007 recommends spacing equal to the rod depth, which might be a better practice if feasible.
2.

Genset Distance

The NEC doesn't specify a minimum distance between the triangular ground rod configuration and the generator set. However, focus on:

Proper Bonding

Ensure the generator's neutral (separately derived system) or frame (non-separately derived system) is correctly bonded to the grounding electrode system via a properly sized Grounding Electrode Conductor (GEC) per NEC 250.66.

Proximity for GEC Length

Position the grounding electrode system as close as practically possible to the generator to minimize the GEC length, while considering safety and maintenance.

Soil Conductivity

Ensure the grounding electrode system is located in an area with good soil conductivity.

Important Considerations



Local Amendments

Always check with your local electrical inspector for any local amendments to the NEC or other regulations that might apply in your jurisdiction. Local rules can sometimes be stricter.

Engineering Judgment

For critical applications (e.g., hospitals, data centers), consult with a qualified electrical engineer. They can perform calculations and design a grounding system that meets the specific needs of your installation.*

Ground Resistance Testing: After installation, test the resistance to ground of the grounding electrode system to verify that it meets the required limits (usually 25 ohms or less).By following these guidelines and consulting with relevant professionals, you can design and install a grounding electrode system for your generator set that is safe, effective, and compliant with applicable codes and standards. Flag for review