You're right, the 2020 NEC (National Electrical Code) significantly changed Section 230.71(B) regarding service disconnects. You're also correct in referencing Mike Holt as a source for understanding these changes. He's a well-regarded expert on the NEC.Let's break down what the change likely addresses and why it's important

The Key Change in 230.71(B) (Generally):

The core idea behind 230.71(B) is to limit the number of service disconnects at a service location. However, the 2020 NEC added provisions to allow for more than six service disconnects in specific circumstances, primarily focused on enhancing safety through separation of those disconnects.

Why the Change? Electrical Shock and Arc Flash Mitigation



Electrical Shock Hazard

Having multiple disconnects allows for isolating specific circuits or equipment, making it safer for workers to perform maintenance or repairs. By de-energizing only the necessary portion, they're reducing the risk of accidentally contacting live parts.

Arc Flash Hazard

Arc flash events are extremely dangerous explosions of energy caused by short circuits. Separating disconnects can help limit the scope and severity of a potential arc flash. Here's how:

Reducing the Arc Flash Boundary

By de-energizing the service disconnect closer to the point where work needs to be done, you reduce the potential arc flash hazard for workers in the immediate vicinity.

Selective Coordination

Separate disconnects can be coordinated in such a way that a fault will cause the upstream disconnect closest to the fault to trip without taking out the entire building's power. This is selective coordination. This minimizes the disruption of other critical circuits.

How the Separation Works

The NEC doesn't just say "add more disconnects." The separation is usually accomplished through one or more of these methods:

Physical Separation

Mounting disconnects in separate enclosures, even in different locations within the building. This reduces the likelihood that a single event (like a tool falling into the enclosure) will affect multiple disconnects.

Barriers/Compartmentalization

Dividing a single enclosure into separate compartments, with each compartment containing a disconnect and having its own door or cover. This provides a degree of physical separation within a single enclosure.

Grouping

The NEC has additional requirements when grouping the service disconnects together.

Key Considerations and Why You Need to Consult the NEC and a Qualified Electrician



Specific Requirements

The exact requirements for separation, labeling, accessibility, and other aspects are spelled out in the NEC (Section 230.71(B) and related sections). The NEC is a complex document, and interpretations can vary.

Engineering Design

The design of a service entrance with multiple disconnects requires careful engineering. Considerations include: Load calculations Coordination of overcurrent protective devices (fuses and circuit breakers) Proper labeling and documentation

In Summary:

The 2020 NEC's changes to 230.71(B) reflect a greater emphasis on electrical safety. By allowing more than six service disconnects under specific, controlled conditions, the code aims to reduce the risks of electrical shock and arc flash for electrical workers and building occupants. However, implementing these changes correctly requires a thorough understanding of the NEC and qualified electrical expertise. Consult with a licensed electrician and electrical engineer to ensure compliance and safety. Flag for review