You're right to be concerned and to consult NEC 225.30. This is a common situation, but the temporary nature of the installation and the specific application (powering downstream panels during a switchboard replacement) can allow for some leniency under the NEC.Here's a breakdown of the situation and considerations: NEC 225.30: Number of Feeders or Branch Circuits. This is the key section. It generally restricts you to one feeder or branch circuit supplying power to a building or structure. The "Exception" is Key: 225.30(A)(4)(b) Here is what the exception says: (4) for the purposes of emergency, legally required, or optional standby systems where one or more of the following conditions apply:(b) Multiple services or feeders shall be permitted to be installed to supply large capacity standby generators with automatic load transfer switches.Analysis of Your Situation


Temporary Nature

This is critical. The installation is temporary to allow for a switchboard replacement. While the NEC does not explicitly define a duration for "temporary" power, it is understood to be for a limited time.2.

Powering Existing Distribution Panels

The fact that the temporary generators are feeding existing distribution panels downstream of the main switchboard replacement is important. This implies that the existing panels and wiring were already designed to handle the load.3.

Safety

Safety must always be paramount.

Justification for Multiple Feeders (with caveats)

You can likely justify the use of multiple feeders in this temporary situation based on the following arguments:

Emergency Standby System

The temp generators serve as emergency standby system as switchboard has been turned off.

Maintaining Service Continuity

The primary goal is to maintain service to existing loads with minimal disruption during the switchboard replacement.

Recommendations and Requirements



Documentation

Crucially, document everything. This documentation should include: The reason for the temporary feeders. The expected duration of the temporary installation. A diagram showing the temporary generator locations, feeder routes, and connections to the distribution panels. A detailed load calculation showing that the existing distribution panels and wiring are not overloaded by the temporary generators. Confirmation that the overcurrent protection (breakers or fuses) in the generator and the distribution panels are properly sized for the connected load and the conductor ampacity.

Coordination with AHJ

It's highly recommended to contact your local Authority Having Jurisdiction (AHJ) – the building inspector or electrical inspector – before implementing the temporary power system. Explain the situation, show them your documentation, and get their approval. This is the best way to ensure compliance and avoid potential issues.

Grounding and Bonding

Ensure proper grounding and bonding of the temporary generators, feeders, and distribution panels. Follow NEC Article 250 requirements for grounding and bonding temporary power systems.

Overcurrent Protection

The overcurrent protection at the generator and the distribution panel must be properly sized and coordinated to protect the conductors and equipment.

Signage

Clearly label all temporary equipment and wiring to indicate that it is a temporary power source.

Generator Placement

Ensure the generators are placed in a safe location with adequate ventilation and protection from the elements.

Why This Works (Potentially)

The AHJ will likely be more lenient with a temporary installation where the goal is to maintain service continuity during a critical repair, provided that: The installation is truly temporary. Safety is prioritized. The existing electrical system is not overloaded. Everything is well-documented and coordinated with the AHJ.

Disclaimer: I am an AI chatbot and cannot provide definitive legal or electrical code interpretation. This information is for general guidance only. Always consult with a qualified electrical engineer and your local AHJ for specific requirements and approvals related to your project. Failure to comply with the NEC and local codes can result in fines, delays, and potentially dangerous situations. Flag for review