Okay, let's break down the correct way to connect the grounding electrode conductor (GEC) in a separately derived system (SDS) like your switched-neutral generator, and why the distinction is important.

The Core Requirement: Connection to the System Bonding Jumper (SBJ)

The primary and correct location for connecting the grounding electrode conductor (GEC) in a separately derived system is to the system bonding jumper (SBJ). This is the general rule.

Why? Creates a Low-Impedance Path

The purpose of the GEC is to provide a low-impedance path for fault current back to the source (the generator in your case). This is crucial for the overcurrent protective devices (circuit breakers or fuses) to operate quickly and clear the fault. Connecting to the SBJ ensures this path.

Proper Grounding of the System

The SBJ bonds the neutral conductor (in a neutral-derived SDS) to the equipment grounding system. By connecting the GEC to the SBJ, you effectively ground the entire electrical system.

The General Rule



250.30(A)(6) Grounding Electrode Conductor Connection to Separately Derived System. "The connection shall be made at any point on the separately derived system from the source to the first system disconnecting means or overcurrent protective device. The connection shall be made in the same manner as service conductors are connected to a grounding electrode conductor as specified in 250.24(A)(1) and (A)(2)."Your Situation: Switched-Neutral Generator and the SBJ

Because you have a switched neutral generator, there is NO neutral in the seperately derived system. This means a system bonding jumper is REQUIRED to bond the equipment grounding system back to the generator frame.

How to Connect the GEC


Locate the System Bonding Jumper (SBJ)

In your switched-neutral generator setup, the SBJ will be a conductor that connects the generator frame (the metal enclosure, which is your equipment grounding point) to the generator windings/source. It is essential that this connection is properly made within the generator itself.2.

Connect the GEC to the SBJ

The GEC should be connected to the SBJ at the generator.3.

Ensure a Solid Connection

Use appropriate connectors listed for grounding and bonding to ensure a secure and reliable connection.

Why Not Directly to the Neutral (or in your case, since it's switched neutral, NOT to the load side of the transfer switch)? Risk of Neutral Current

In a standard, non-switched-neutral system, connecting the GEC directly to the neutral could cause unwanted neutral current to flow through the grounding electrode, potentially creating a shock hazard and interference with sensitive electronic equipment.

Fault Current Path

The most effective path for fault current in your switched-neutral system is the equipment grounding system (connected through the SBJ) back to the generator frame (and thus, the source).

Important Considerations and Recommendations



Generator Instructions

ALWAYS follow the manufacturer's instructions for grounding the generator. The manufacturer might have specific recommendations for GEC connection based on the generator's design.

Qualified Electrician

This type of connection is safety-critical. If you're not a qualified electrician, it's strongly recommended that you have a licensed electrician perform the grounding and bonding of your generator. Improper grounding can be dangerous.

Local Codes

Always comply with local electrical codes and regulations, as they may have specific requirements for generator installations.

In summary, the most appropriate connection for the grounding electrode conductor is to the system bonding jumper, which connects the frame of the generator to the equipment grounding system. It is the only permitted connection by the NEC. This ensures a solid ground and a direct, low-impedance path for fault current. Flag for review