You're right that there isn't a blanket statement that every building needs its own service disconnect. However, the NEC strongly leans towards requiring a disconnect at each building or structure, and there are very specific and limited exceptions.Here's the breakdown and why this can be complex

The General Rule: Disconnect at Each Building
NEC 225.31 Disconnecting Means. "Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure."This is the core requirement. It means if you're feeding a building from another source (like another building), you generally need a way to disconnect power at that building. NEC 225.32 Location. "The disconnecting means shall be installed either inside or outside of the building or structure served at a readily accessible location nearest the point of entrance of the supply conductors."This clarifies that the disconnect needs to be easily accessible and close to where the power enters the building.

Why the Emphasis on Disconnects at Each Building? Safety

Emergency responders and electricians need to be able to quickly de-energize a building for safety reasons (fire, electrical faults, etc.). Having a disconnect readily available at the building is crucial.

Maintenance

Disconnecting power to one building shouldn't require affecting power to other buildings.

Isolation

Helps isolate faults and prevent them from spreading.

The Critical Exception: "Single Management" and Specific Conditions

The situations where multiple buildings might share a single service disconnect (located outside) are very limited and hinge on the "single management" concept. Here's what NEC 225.32 exception says: Exception

For a one-family dwelling and its accessory structure(s), the disconnecting means shall be permitted to be located elsewhere on the premises.

Exception

For a two-family dwelling and its accessory structure(s), the disconnecting means shall be permitted to be located elsewhere on the premises.

Exception

Where documented safe work practices and equipment are in place, and where the disconnecting means is under the control of the building's operators or maintenance personnel.

Breaking Down the Exceptions



One and Two Family Dwellings and their Accessory Structures

This is the most common exception. For example, a house and a detached garage might share the same service disconnect, even if the garage has its own subpanel. The key is that it's all considered part of the same dwelling and premises.

"Documented Safe Work Practices and Equipment"

This exception is very specific and much harder to meet in a general scenario. It implies a highly controlled environment (like an industrial facility) where: There are written procedures for working on electrical equipment safely. Personnel are trained and qualified to follow those procedures. They have the necessary equipment (PPE, testing tools) to work safely. The disconnect is readily accessible only to those trained personnel.

Key Considerations and Questions to Ask

Before even thinking about sharing a service disconnect outside for multiple buildings, ask yourself:1.

Ownership and Management

Are the buildings under single ownership and single management? If they are separate businesses, even on the same property, sharing a service disconnect is almost certainly not allowed.2.

Accessibility

Is the disconnect readily accessible to anyone who needs it in an emergency (fire department, other tenants)? "Readily accessible" means it cannot be locked, obstructed, or require special tools to access.3.

Maintenance and Coordination

How would maintenance or repairs on one building's electrical system affect the other building? Would both buildings have to be shut down?4.

Safe Work Practices

Does a documented safety program with trained personnel exist that manages the disconnect?

In summary

While sharing a service disconnect is possible under very specific conditions and the "single management" exception, it's generally

not recommended and requires a thorough understanding of the NEC and local codes. It's much safer and more practical to provide a dedicated disconnect at each building unless you meet the exception requirements precisely.

Always consult with a licensed electrical contractor and your local electrical inspector before making any decisions about service disconnects. They can assess your specific situation and ensure compliance with all applicable codes and regulations. Trying to save money by sharing a disconnect can create significant safety hazards and potential code violations. Flag for review