Let's break this down, focusing on the NEC and the specific concerns you've raised about fire pump feeders, generators, and tap rules.

Key Concepts and NEC Sections



Fire Pumps (NEC Article 695)

Fire pumps are critical life-safety equipment. Article 695 provides very specific rules about their power sources, reliability, and protection.

Standby Generators (NEC Article 701 & 702)

Standby generators provide backup power. Article 701 covers legally required standby systems (like life safety) and 702 covers optional standby systems.

Services (NEC Article 230)

The service is the connection from the utility to the building. It has specific rules about overload protection, disconnects, and grounding.

Feeders (NEC Article 215 & 240 Part IV)

Feeders carry power from the service to a subpanel or load. They are subject to overload protection requirements, and tap rules.

Tap Rules (NEC 240.21)

Tap rules allow you to reduce the size of a feeder for a short distance, if specific conditions are met regarding overcurrent protection, length, ampacity, and the nature of the load.

Analyzing Your Scenario


Fire Pump Service

You're correct. Fire pumps are almost always fed by either: A dedicated service, or A tap ahead of the main service disconnect (per 695.3(A)(1) & (2)).When a tap is ahead of the main, it does not fall under the tap rules. The exception in 240.21(B)(1) allows this, precisely because the fire pump is critical life safety. The tap to the fire pump is considered a service conductor and must comply with Article 230.
2.

Generator as a Power Source

The generator serves as an alternate source of power. The intent is to automatically switch to the generator if the normal power source fails.3.

The Question: Generator Connection as a Feeder? This is where the specific arrangement matters and the potential application of tap rules comes into play. Generally, the connection between the generator and the fire pump transfer switch is considered a feeder. Why a Feeder? Because the generator isn't the original source of power like the utility. It's an intermediate source, providing power after the utility fails. The path from the generator to the fire pump transfer switch is carrying power to a load (the fire pump) and is therefore a feeder. Application of Tap Rules

Because the generator connection is likely considered a feeder, tap rules would apply unless there's a specific exception or rule that overrides them.

NEC Considerations for Fire Pumps and Generators



695.3(C) Alternate Source Connection. As you've mentioned, this section allows the alternate source to be connected to the transfer switch. The code DOES NOT require a breaker at the generator for this purpose. 695.6(H) discusses the overcurrent protection of the conductors from the alternate source to the transfer switch. 695.6(H) Protection of Alternate Source Conductors

This section states that the conductors from the alternate source to the transfer switch should be protected from overload. There is no requirement for a specific breaker size, but you should consider the locked rotor amps of the fire pump motor.

Answering Your Specific Question

> "The question is, does the connection directly at the generator qualify as a feeder requiring it to be subject to the feeder tap rule distances?"Yes, generally the connection from the generator to the fire pump transfer switch will be considered a feeder. Unless an exception applies, it will be subject to tap rules. You are responsible for meeting the conditions of the tap rules in order to apply them.

Crucial Points and Best Practices



AHJ is Key

Ultimately, the Authority Having Jurisdiction (AHJ) has the final say. Discuss your design with the AHJ before installation to ensure compliance.*

Documentation

Thoroughly document your design, including load calculations, conductor ampacity calculations, overcurrent protection sizes, and lengths of conductors. This will help demonstrate compliance to the AHJ.

In summary, you are correct in assuming the fire pump connection to the standby generator is likely a feeder subject to tap rules. Be sure to verify with your AHJ, and document all aspects of your design to show compliance. Flag for review