Okay, let's break down the issues and how to approach this situation. You're right to be concerned about shared neutrals when re-feeding existing apartment circuits to a new meter bank. It's a critical safety and code compliance issue.

Understanding the Problem: Shared Neutrals and Meter Banks Shared Neutrals

In older apartment buildings (and sometimes even newer ones due to cost savings), multiple apartments might share a single neutral conductor back to the main panel. This was more common in the past.

Why it's a Problem

If the neutral path isn't adequately sized or if the loads are unbalanced between the phases sharing a neutral, you can get:

Overloaded Neutral

The neutral current can exceed the conductor's rating, leading to overheating and potentially fire.

Voltage Fluctuations

Uneven loading can cause voltage imbalances in the apartments.

Phantom Voltages

Potentially dangerous voltage on supposedly "off" circuits.

Code Violations

Modern electrical codes generally discourage and sometimes prohibit shared neutrals (especially between different dwelling units).

Meter Bank Arrangement

The physical arrangement of the meters can matter, if existing shared neutrals are present and are tied to specific meter positions.

Analyzing Your Situation and Determining the Next Steps

Here's a systematic approach to determine if the meter arrangement matters. I'll also provide general recommendations.1.

Absolutely Must: Identify and Verify Existing Neutral Configuration (This is the most critical step!) Testing is Key

You cannot rely on assumptions. You must thoroughly test the existing wiring before disconnecting anything.

Neutral Tracing



Power OFF

Disconnect power to the entire existing meter bank before doing any testing.

Continuity Testing

Use a multimeter to check for continuity between the neutral conductors of different apartment circuits. Specifically: Check continuity between the neutral of apartment 1 and apartment 2, apartment 1 and apartment 3, apartment 2 and apartment 3, and so on for all apartment neutrals connected to the old meter bank. If you find continuity between the neutrals of different apartments, that confirms the existence of shared neutrals.

Neutral Identification

Once you identify which neutrals are shared, carefully label each neutral conductor with its corresponding apartment number and indicate which other apartments it shares a neutral with. Use clear, durable labels.2.

Document the Existing Meter Bank Configuration



Take Detailed Photos

Photograph the existing meter bank, paying close attention to the wiring connections at each meter. Zoom in to capture the wire colors and terminal markings.

Create a Wiring Diagram

Sketch a diagram showing which apartment feeds into which meter position in the existing meter bank. Note wire colors. This becomes your "as-built" reference.3.

Analyze the New Meter Bank Cut Sheet

Understand the new meter bank's terminal layout and how it is set up to land the feeders from the apartments.4.

If Shared Neutrals Are Present (MOST LIKELY)



Option 1: (Best Option - Recommended if feasible) Eliminate Shared Neutrals



Rewire from Apartments

The ideal solution is to rewire each apartment with dedicated neutral conductors back to the main distribution panel (if it is close enough) . This eliminates the problems associated with shared neutrals and brings the installation up to current code. This is likely a substantial undertaking, but it's the safest and most reliable long-term solution. You'll need to properly size the new neutral conductors based on the expected load.

Neutral Termination

If you are running dedicated neutrals to the apartments, you should land each neutral on a separate neutral bus in the panel.

Modern Code

This approach also ensures compliance with modern electrical codes, which generally prohibit shared neutrals between dwelling units.

Option 2: (Less Desirable, but Potentially Necessary) Maintain Shared Neutrals (Carefully)



Exact Replication

If you absolutely must maintain the shared neutrals, the only safe way to do it is to exactly replicate the existing wiring configuration in the new meter bank. This means: Apartment 1's line conductors and neutral must connect to the same meter position as they did in the old meter bank. Apartment 2's conductors must connect to their original meter position, and so on. The shared neutrals must be connected together at a suitably rated terminal block within the new meter bank enclosure. The connection must be secure and rated for the combined neutral current. Do not rely on wire nuts alone.



Neutral Sizing Verification

Crucially, you must verify that the shared neutral conductors are adequately sized to handle the combined load of all the apartments sharing that neutral. Consult the NEC (National Electrical Code) for guidance on neutral conductor sizing. If the existing neutrals are undersized, you cannot proceed with this option.

Diagram the New Configuration

Carefully diagram how the shared neutrals are connected in the new meter bank. This is important for future troubleshooting.

Inspect and Torque Connections

After connecting the neutral conductors into the terminal blocks, make sure you follow manufacture requirements for torque. Use a torque screwdriver to torque the screws down.5.

If No Shared Neutrals Are Present

You have much more flexibility in the meter bank arrangement. You can connect the apartment feeders to any meter position, as long as the voltage and current ratings are appropriate. Still, document the wiring configuration and follow good wiring practices.

Specific Considerations for the Siemens Meter Bank (Based on Cut Sheet)



Enclosure Size

Make sure the new Siemens meter bank enclosure is large enough to accommodate all the existing wiring, the new meters, any necessary terminal blocks for shared neutrals (if applicable), and proper bending space for the conductors.

Neutral Bar/Terminal Blocks

Examine the Siemens meter bank's neutral provisions. Will it accommodate shared neutrals, and is there sufficient space and capacity to terminate them safely? If not, you'll need to add appropriately rated terminal blocks.

Meter Socket Ratings

Verify that the meter sockets in the Siemens meter bank are rated for the voltage and current requirements of the apartments.

Check UL Listing

Check the new Siemens meter bank to ensure the equipment is UL approved for apartment complexes.

Important Cautions and Recommendations



Licensed Electrician

This work must be performed by a qualified and licensed electrician who is experienced in multi-meter installations and familiar with local electrical codes.

Permits and Inspections

Obtain all necessary permits and schedule inspections with your local electrical inspector. The inspector will verify that the installation is safe and code-compliant.

"No Load" Conditions

Be very careful when disconnecting and reconnecting neutrals. Always ensure that there is no load on the circuits when working with neutrals. Disconnect breakers to the apartments to ensure a no load situation.

Arc Flash

Be aware of arc flash hazards when working with energized electrical equipment. Use appropriate PPE (personal protective equipment).

Future Upgrades

While the new meter bank allows for future upgrades, it is still very important to evaluate the existing service entrance and panel capacity to ensure it can accommodate any potential increase in load from upgrades.

Communication with Tenants

Keep the tenants informed about the work being done and any planned outages.

NEC Compliance

Always adhere to the latest version of the National Electrical Code (NEC) and any applicable local codes.

Documentation

Keep thorough records of all wiring configurations, test results, and modifications made to the electrical system.

In Summary:The most crucial step is to thoroughly investigate the existing wiring and determine if shared neutrals are present. If they are, the safest approach is to eliminate them by rewiring each apartment with a dedicated neutral. If that's not feasible, you must replicate the existing wiring configuration exactly* and ensure that the shared neutral conductors are adequately sized. Engage a qualified electrician, obtain permits, and have the installation inspected to ensure safety and code compliance. Good luck! Flag for review