Okay, let's break this down to make sure you're doing this safely and in accordance with code. This is a common situation, but there are critical details.

Understanding the Goal

The primary goal is to provide a safe and effective ground fault current path back to the generator during a fault condition. This is crucial for the overcurrent protection (breakers) to trip and clear the fault quickly. Relying solely on earth for this isn't reliable enough.

Here's a step-by-step breakdown of the situation


Generator Type & Configuration



Is it a Separately Derived System (SDS) or a Non-Separately Derived System? This is the most important question. SDS: The generator neutral is isolated from the premises wiring system neutral. Usually, the generator has its own neutral-to-ground bond. Non-SDS: The generator neutral is connected to the premises wiring system neutral.2. Bonding is Always Required

Whether an SDS or Non-SDS, you MUST have a grounding electrode system (GES) at the generator or at the first point of connection of the generator output to the building.3.

Why Not Just a Ground Rod

A single ground rod is often not sufficient as the sole grounding electrode. The primary purpose of the grounding electrode system (ground rods, Ufer, etc.) is not to conduct fault current. It is to limit voltage imposed by lightning, line surges, or unintentional contact with higher voltage lines and to stabilize the voltage to ground during normal operation. A single ground rod might not provide a low enough impedance path for proper fault clearing.4.

Your Situation - Using the Building's Grounding Electrode System (GES)



This is the preferred method if it meets code requirements. You are proposing to utilize the existing building's GES (Ufer, water, steel, planter ground rod). The key is the effectiveness of this grounding system and the quality of your connection.5. Specific Guidance for Your Proposal (Bonding to the Electrical Room Bus Bar)



This is generally a good approach if done correctly! The proper way to do this is to run a properly sized grounding electrode conductor (GEC) from the generator frame (and neutral if it's an SDS) to the existing building's grounding electrode system (ground bar in the electrical room). Sizing the Grounding Electrode Conductor (GEC)

This is critical. The GEC must be sized according to NEC 250.66 based on the largest ungrounded conductor(s) from the generator. Do not guess. Use the table, and don't undersize.

Connection Quality

The connection to the ground bar in the electrical room must be a listed and labeled connector suitable for grounding and bonding. Make sure it's clean, tight, and corrosion-resistant.

Verify the Building's GES

You mentioned Ufer, water, steel, and a planter ground rod. This sounds compliant but make sure the Ufer is actually encased in concrete (check documentation). Also, verify the water pipe is metallic and continuous. Make sure the ground rod in the planter is also of adequate size, spacing, and connection.6.

Separately Derived System (SDS) vs. Non-Separately Derived System (Important) Separately Derived System (SDS)

The generator neutral is not connected to the building's neutral at any point. The generator must have its own neutral-to-ground bond at the generator. Typically, this bond is established at the generator's output terminals. You still need to run a GEC from the generator's frame to the building's grounding electrode system (ground bar).

Key Point

The neutral and ground are bonded only at the generator for an SDS.

Non-Separately Derived System

The generator's neutral is connected to the building's neutral. The generator neutral cannot be bonded to ground at the generator. The neutral-to-ground bond happens only at the service entrance. You still run a GEC from the generator frame to the building's grounding electrode system.7.

Grounding Conductor vs. Grounded Conductor Grounded Conductor: The neutral conductor, intentionally grounded. Grounding Conductor: The conductor that connects non-current-carrying metal parts (like the generator frame or equipment enclosures) to the grounding electrode system. Never connect the grounded (neutral) conductor to the grounding conductor, except at the service equipment or the source of a separately derived system.8. Local Amendments in Los Angeles

Los Angeles (and California in general) often have amendments to the NEC. Contact the local inspection authority to make sure you are in compliance.

Here's what I recommend you do


Determine if your generator is an SDS or Non-SDS. Consult the generator's documentation and wiring diagrams.2. Calculate the required size of the grounding electrode conductor (GEC) per NEC 250.66.3. Run the properly sized GEC from the generator frame (and generator neutral if an SDS) to the building's ground bar. Use listed connectors.4. Verify the integrity and adequacy of the building's grounding electrode system (Ufer, water, steel, etc.). Make sure everything is properly connected and in good condition.5. Consult with a qualified electrical engineer or licensed electrician. This is not a DIY project. They can review your setup, ensure code compliance, and verify the connections.6. Call the LA County building inspector (or the inspector from your city within LA County). You will likely need to get this inspected. They can confirm that the installation is compliant with all relevant codes and local amendments.7. Documentation

Keep records of the generator specifications, wiring diagrams, GEC size calculations, and inspection approvals.

Important Safety Considerations



Backfeeding

Ensure there is absolutely no way the generator can backfeed onto the utility grid. This is a very dangerous situation. Use appropriate transfer switches.

Qualified Personnel

Only qualified electricians should perform these connections.*

Lockout/Tagout: Always use proper lockout/tagout procedures when working with electrical equipment.By following these steps and getting professional help, you can safely and effectively connect your generator to the building and provide temporary power. Good luck! Flag for review