Okay, let's break down your situation and address your proposed temporary solution, keeping in mind safety and code compliance are paramount.

Understanding the Situation



Unpermitted Generator

You have an existing 20kW diesel generator installed without permits, which is a code violation.

Service Issues

Recent service replacement has height issues and triggered an electrical inspection request from the local authority (LJHA).

Flood Plane Issue

The generator location is below the flood plain, another code violation.

Manual Transfer Switch

You have a 200A service-rated manual transfer switch adjacent to the new meter socket.

Goal

Get the electrical inspection passed for the service upgrade while addressing the generator situation.

Analyzing Your Proposed Temporary Solution (50A Generator Inlet)

While your approach seems like a quick fix, there are significant concerns:

Safety

Connecting a generator directly to the panel with a 50A inlet and relying on manually turning off breakers introduces several safety hazards. Accidental backfeeding is a major risk, potentially energizing the utility grid and endangering utility workers or neighbors. Even with labels, human error is a significant concern.

Code Compliance (NEC)

Here's where it gets tricky. While it MIGHT technically meet the letter of some sections if everything is done perfectly, it almost certainly violates the spirit of the code, which prioritizes safety and reliable operation. Here's why:

Article 702 (Optional Standby Systems)

The NEC covers optional standby systems (like generators). The requirements for transfer equipment, overcurrent protection, and system grounding are pretty strict. Your setup is unlikely to meet these standards without a proper automatic transfer switch or, at the very least, a listed and labeled manual transfer switch specifically designed for generator input.

Article 408.36 (Overcurrent Protection)

The load center connected to the generator inlet needs proper overcurrent protection to prevent overloading the generator or the wiring. A 50A receptacle doesn't guarantee that the generator is only loaded to 50A; therefore, you must have overcurrent protection on the generator side of the inlet.

Backfeed Protection

NEC requires measures to prevent backfeeding the utility grid. Relying solely on manually turning off breakers is NOT sufficient.

Generator Sizing/Load Calculation

Even with a 50A inlet, you need to calculate the actual load you'll be placing on the generator to ensure it's not overloaded. This is more than just guessing; it requires a formal load calculation.

Inspection Approval

It is highly unlikely that an inspector will approve this setup, given the safety concerns and potential code violations. They are responsible for ensuring the installation meets minimum safety standards.

Issues with the Existing Manual Transfer Switch

While the existing 200A manual transfer switch could be a legal disconnecting means for the service, it's not suitable for the generator. You can not use that as the disconnect for the generator. The generator MUST be able to feed back to the house through an approved and designed automatic transfer switch or a proper manual transfer switch.

Recommendation

This is a complex situation that requires a comprehensive approach:1.

Contact the LJHA (Local Authority)

The best course of action is to contact the LJHA before doing anything. Explain the situation transparently. Ask them what steps they require to bring the generator system into compliance and get the service inspection passed. Being proactive and honest will often result in a more cooperative outcome.2.

Professional Load Calculation and System Design

Hire a qualified electrical engineer or licensed electrician with generator system expertise. They should: Perform a proper load calculation to determine the actual load the generator needs to support. Design a compliant generator system that meets all applicable codes (NEC, local amendments, etc.). Specify the correct automatic transfer switch (or potentially a listed/labeled manual transfer switch designed for generator input, if that's acceptable to the AHJ). Address the flood plain issue by relocating the generator (ideally) or implementing a flood protection plan approved by the AHJ.3.

Generator Relocation/Flood Protection

The generator's location below the flood plain is a major issue. Relocating the generator to a higher elevation is the best solution. If relocation is impossible, you'll need to explore flood protection measures (raising the generator on a platform, building a flood barrier, etc.) that are approved by the local authority.4.

Permitting

Obtain all necessary permits for the generator installation before starting any work.5.

Proper Installation

Ensure the generator system is installed by a licensed electrician who is familiar with generator installations and code requirements.6.

Grounding and Bonding

Ensure proper grounding and bonding of the generator system according to NEC requirements.7.

Surge Protection

Install a surge protective device (SPD) at the load center to protect against voltage surges. While good practice, this won't be a substitute for a compliant generator system.

Why This Approach Is Necessary



Safety

Protects occupants, electrical workers, and the public from hazards.

Code Compliance

Avoids fines, penalties, and potential liability.

Reliability

Ensures the generator system operates safely and reliably when needed.

Long-Term Solution

Addresses the root causes of the problems, rather than just applying a temporary fix.

In summary, while your proposed temporary solution may seem expedient, it is highly unlikely to be approved by the inspector and poses safety risks. Contacting the local authority and working with a qualified professional is the only responsible way to address this complex situation. Flag for review