Okay, let's break down these questions regarding service drops for multi-family residential (MFR) buildings.

Question 1: Adding a New Service Drop to an Existing MFR with Existing Service Generally Yes, with Conditions. The fact that the utility company is willing to provide a second drop is a huge positive. Their willingness is often the biggest hurdle. However, several factors will determine the actual feasibility and compliance: NEC Compliance

The primary governing factor is the National Electrical Code (NEC), as adopted and amended by your local jurisdiction. Key sections to consider are:

230.2 Number of Services

The NEC generally limits a building to one service. However, there are exceptions, specifically:

(A) Special Conditions

This exception allows multiple services under specific circumstances like:

Capacity Requirements

If the total calculated load exceeds the capacity of a single service (taking into account things like demand factors), multiple services are permitted. This could apply if you genuinely need more than 400A in the future, and the existing service is already near its limit.

Different Characteristics

If different voltages, frequencies, or phases are required, multiple services are allowed. This probably doesn't apply to a typical residential MFR.

Large Physical Size

If the building is so large that serving it with a single service drop is impractical (e.g., excessive voltage drop), multiple services may be permitted. This is less likely in a typical MFR scenario.

(D) Multiple Occupancy Buildings

This is more relevant. It might allow separate services, but typically only if each occupancy has its own service entrance.

Local Amendments and Utility Requirements

Your local electrical code might have amendments that are more or less restrictive than the NEC. The utility company also has its own policies and specifications for service drops and metering. Their requirements are paramount. They'll dictate things like:

Service Point

Where the utility's responsibility ends and yours begins.

Metering

How each unit will be metered. Will the second drop serve only specific units, or will it be a common area service?

Equipment Specifications

What type of service disconnects, enclosures, and grounding are required.

Load Calculations

The utility will likely want to see detailed load calculations for each unit and the total building load.

Accessibility

You mentioned accessibility, which is good. The service equipment (disconnects, meters, etc.) must be readily accessible to all occupants, as well as the utility. Proper labeling is critical.

Diversity and Demand Factors

Even though the sum of each unit's breaker sizes might be around 400A, the actual peak load is probably significantly lower due to diversity (not everyone uses everything at the same time) and demand factors. You need to use NEC Article 220 to perform proper load calculations.

Steps to Take


Consult with a Licensed Electrical Contractor

Absolutely essential. They will know the local codes and can work with the utility company.2.

Contact the Utility Company

Get their specifications and requirements in writing. Understand their metering plans.3.

Detailed Load Calculations

Perform accurate load calculations using NEC Article 220 for each unit and the total building.4.

Submit Plans to the AHJ (Authority Having Jurisdiction)

This is your local building department or electrical inspector. They will review the plans for compliance with the NEC and local codes.

Question 2: Grandfathering of Two Existing Service Drops Likely Yes, But Document Everything! "Grandfathering" (or "legally nonconforming") generally means that something that was legally installed under a previous code is allowed to remain even if it doesn't meet current code requirements. However, this comes with caveats: No Substantial Modifications

The key is that you generally cannot make significant changes or additions to the existing service without bringing the entire system up to current code. For example, if you increase the size of a service entrance conductor or add new loads to the service, the AHJ may require you to bring the entire service into compliance with the current code. Replacing a meter, or changing out a main breaker for the same size is usually okay.

Documentation

CRITICAL. You need to have proof that the services were legally installed under a previous code. This could be: Permit records from the time of installation. Inspection reports. Historical utility records. Invoices from the original electrical contractor. Even photos or witness statements can help, although official records are best.

AHJ Discretion

The AHJ has the final say. They can interpret the code and grandfathering provisions.

Safety Considerations

Even if something is grandfathered, if it presents a safety hazard, the AHJ can require it to be upgraded.

Important Considerations for Grandfathered Services



Proper Maintenance

Grandfathered systems still need to be properly maintained. Replace damaged components with like-for-like parts.

Grounding and Bonding

Ensure that the grounding and bonding systems are still effective and meet at least the code requirements that were in place when the services were originally installed.

In Summary Adding a second service drop is possible, but depends on the utility's willingness, NEC compliance, and local codes. Engage a licensed electrician.* Grandfathering of existing services is possible, but requires proof of legal installation under previous codes. Avoid substantial modifications that trigger upgrades. Document everything, and make sure the system is safe.

Disclaimer: I am an AI Chatbot. This information is for general guidance only and should not be considered professional electrical advice. Always consult with a qualified and licensed electrical contractor and your local Authority Having Jurisdiction (AHJ) for specific project requirements and code compliance. Flag for review