You're right to be cautious and question this configuration. Here's a breakdown of the NEC requirements and why your proposed setup needs careful consideration

NEC Requirements for Fire Pump Power

The NEC has specific requirements for the power supply to fire pumps, primarily found in Article 695 (Fire Pumps). Key points include: Reliability

The core principle is that the fire pump power source must be reliable and capable of delivering the necessary power for the pump to operate under fire conditions. This reliability is paramount.

Independent Service or Separate Service

Typically, fire pumps are fed from either: A

service dedicated solely to the fire pump, or A separate service widely separated from the other building service. Emergency Power Acceptance

The NEC does allow for an emergency power source (like a generator) to power a fire pump,

BUT with strict conditions.

Analysis of Your Proposed Configuration

Let's dissect your proposal and see where it might fall short:1. Generator #1 (Emergency Panel & Maybe Fire Pump)

This generator feeds the building's egress emergency panel. This means it's likely sized to handle lighting, exit signs, and perhaps some minimal life safety loads.

Problem

Putting the fire pump on the same generator as other emergency loads can compromise the reliability and capacity dedicated to the fire pump. If the building experiences a fire and the normal power fails, this generator will be heavily loaded. The fire pump's critical load might not get the priority it needs, potentially leading to reduced pressure or failure.2.

Generator #2 (Dedicated Fire Pump)

This generator is dedicated to the fire pump. This is good and aligns with the "reliable power source" principle.

Issue

You mention a "fire pump transfer switch/controller". The critical question is:

How does the system know to switch over to Generator #2 and only supply the fire pump? The transfer switch needs to isolate the fire pump from the main building's normal power and potentially from Generator #1, ensuring it only gets power from its dedicated generator.

Why This Could Be Problematic Under NEC Load Calculations and Capacity

NEC 695 requires specific load calculations to ensure the generator dedicated to the fire pump has sufficient capacity. If the generator is undersized or has other loads connected to it, it could be a violation.

Coordination

The operation of the transfer switch needs to be carefully coordinated. It must switch to the fire pump's generator quickly and reliably.

Testing

The entire system, including both generators, the transfer switch, and the fire pump controller, must be thoroughly tested under load to ensure proper operation. NEC 695 has specific testing requirements.

Signage and Documentation

Clear signage is required to identify the fire pump power source and any associated equipment.

Automatic Starting

Fire pumps should start automatically on loss of normal power. The generator system needs to accommodate this.

What to Do1. Consult with a Qualified Electrical Engineer

This is not a DIY situation. You need an engineer experienced in fire protection systems and NEC requirements. They can perform the necessary load calculations, design the system correctly, and ensure compliance.2.

Review NEC Article 695 Carefully

Understand the specific requirements for fire pump power.3.

Consider a Dedicated Service

The best and most reliable option is often a dedicated electrical service solely for the fire pump. This eliminates the complexities of generators and transfer switches.4.

If Using Generators, Ensure Proper Transfer Switch Operation

The transfer switch must isolate the fire pump from other loads and the main service when the generator is running. It should also be designed to prioritize the fire pump load.5.

Get AHJ Approval

The Authority Having Jurisdiction (AHJ) must approve the fire pump power system. They will have the final say on whether your design meets code.

In summary, while using a generator for a fire pump is possible under the NEC, it's complex and requires strict adherence to the code. Your proposed configuration raises concerns about reliability and capacity, especially with the first generator also serving the building's emergency panel. Seek expert engineering advice to ensure a code-compliant and reliable fire pump power system. Flag for review