Okay, let's break down what's needed for a double-gang meter base feeding two main disconnect panelboards, focusing on code compliance and common best practices. This is a common setup for duplexes or situations where you want to separate power distribution.

Key Code Considerations (Based on NEC - National Electrical Code)



NEC Article 230 - Services

This is the primary article governing service entrances.

NEC Article 250 - Grounding and Bonding

Critical for safety.

NEC Article 310 - Conductors for General Wiring

Sizing and ampacity.

NEC Article 408 - Switchboards and Panelboards

Construction and installation.

Here's a breakdown of the requirements and additional items to consider


Service Entrance Conductors (SE Conductors)



Sizing

The SE conductors from the meter base to each main disconnect panelboard MUST be sized based on the calculated load for each dwelling unit/panelboard, per NEC 220. This requires a load calculation for each unit. The conductors must have an ampacity equal to or greater than the calculated load, but never less than the rating of the main disconnect.

Material

Copper or Aluminum conductors are typically used, be sure to use the proper connectors for the conductors (especially AL rated connectors for aluminum).

Overcurrent Protection

The main disconnects must be readily accessible and suitable for service equipment. The overcurrent protection (circuit breaker or fused switch) must be rated to protect the conductors, per NEC 240.4. The sum of the main disconnects may or may not be higher than the meter enclosure, because of NEC 220.61 which allows the service to be smaller than the total load.

Physical Protection

SE conductors need physical protection, usually in conduit. The type of conduit depends on the location (underground, exposed, etc.). Common choices are PVC, RMC (Rigid Metal Conduit), or EMT (Electrical Metallic Tubing).

Number of Conductors

Typically, you'll have two ungrounded conductors (hot/phase), a grounded conductor (neutral), and an equipment grounding conductor (ground).2.

Meter Base



Rating

The meter base must have an ampacity rating equal to or greater than the calculated total service load for both dwelling units/panelboards, considering demand factors.

Listing

It must be listed for its intended use (UL listed is common).

Suitable for Environment

It should be rated for outdoor use (NEMA 3R or better).

Short Circuit Current Rating (SCCR)

Verify the SCCR of the meter base is sufficient for the available fault current at the service entrance. This is a crucial safety consideration.

Neutral Connection

The meter base will have a provision for connecting the neutral conductor. The neutral connection is usually where the neutral-to-ground bond for the service occurs.3.

Main Disconnect Panelboards



Rating

Each panelboard must have a main disconnect (circuit breaker or fused switch) with an ampacity rating at least as high as the calculated load for the dwelling unit/panelboard it serves.

Suitable for Use as Service Equipment

The panelboards must be listed and labeled "Suitable for Use as Service Equipment." This means they have a neutral-to-ground bonding point.

Location

The panelboards must be readily accessible. NEC 230.70(A)(1) requires the service disconnecting means to be installed at a readily accessible location either outside a building or inside nearest the point of entrance of the service conductors.

Short Circuit Current Rating (SCCR)

The panelboards must have an adequate SCCR for the available fault current.

Overcurrent Protection

Branch circuit breakers or fuses must be installed to protect the branch circuits within each panelboard.

Labeling

Each panelboard must be clearly labeled to indicate what it serves (e.g., "Unit A Panel," "Unit B Panel").

Neutral and Grounding

The neutral bus bar is bonded to the panel enclosure only in the service equipment. Downstream subpanels will have a floating neutral (neutral isolated from the enclosure).4.

Grounding and Bonding



Grounding Electrode System

A grounding electrode system must be established, consisting of items like a ground rod, metal water pipe (with supplemental electrode), or concrete-encased electrode (ufer ground). NEC Article 250 details the requirements.

Main Bonding Jumper (MBJ)

A main bonding jumper (wire or busbar) must connect the neutral busbar to the panel enclosure in each of the service equipment panelboards. This creates the necessary bond between the neutral and ground.

Equipment Grounding Conductors (EGCs)

EGCs must be run with all branch circuits to provide a low-impedance path for fault current back to the source, ensuring proper operation of overcurrent devices.

Bonding of Metal Components

All metal enclosures, raceways (conduit), and other non-current-carrying metal parts must be bonded together to create an effective ground-fault current path.5.

Wiring Methods



Conduit

As mentioned earlier, use appropriate conduit for the environment and application.

Connectors

Use listed connectors suitable for the type of conductor (copper or aluminum) and the type of conduit.6.

Clearances



Working Space

Ensure adequate working space around the panelboards, as specified in NEC 110.26. This includes sufficient depth, width, and height.

Headroom

Sufficient headroom must be maintained.7.

Load Calculations



NEC Article 220

Perform accurate load calculations for each dwelling unit/panelboard to determine the minimum service size and conductor ampacity. Consider general lighting, receptacle outlets, appliances (fixed and portable), heating/cooling equipment, and any other loads.

Demand Factors

You can apply demand factors (NEC 220.42, etc.) where permitted to account for the fact that not all loads will be operating at their maximum simultaneously.
8.

Coordination



Utility Company

Coordinate with the local utility company regarding their requirements for meter location, service entrance equipment, and any specific regulations they may have. They often have specific requirements for the meter base and disconnect.

Inspections

Schedule inspections with the local electrical inspector to ensure compliance with the NEC and local codes.

Additional Considerations



Accessibility

Ensure that the meter and disconnects are readily accessible to both the occupants and the utility company.

Future Expansion

Consider the possibility of future expansion of the electrical load when sizing the service. It's often wise to oversize slightly.

Surge Protection

Consider installing a surge protective device (SPD) at the service entrance to protect sensitive electronics from voltage surges.

Arc Fault Circuit Interrupters (AFCIs)

AFCI protection is required for many circuits in dwelling units (NEC 210.12).

Ground Fault Circuit Interrupters (GFCIs)

GFCI protection is required for receptacles in specific locations (NEC 210.8).*

Documentation

Keep accurate records of load calculations, conductor sizes, overcurrent protection ratings, and grounding/bonding details. This will be helpful for future maintenance and troubleshooting.

In Summary

To ensure code compliance and a safe, reliable installation for a double-gang meter base feeding two main disconnect panelboards:1. Perform accurate load calculations for each dwelling unit/panelboard.
2. Size the service entrance conductors, meter base, and main disconnects appropriately.3. Establish a proper grounding and bonding system.
4. Use listed equipment and wiring methods.5. Provide adequate working space and clearances.
6. Coordinate with the utility company and local electrical inspector.7. Document everything.

Disclaimer: This information is intended for general guidance only. Electrical work is dangerous and should only be performed by qualified electricians who are familiar with the NEC and local codes. Always consult with a licensed electrician for specific installations. This response is not a substitute for professional advice. Flag for review