What is the rating of the service disconnect based on?

The rating of the service disconnect is based on the highest continuous current trip setting of any installed breaker. This is a critical aspect of electrical design and safety because the service disconnect must be capable of handling the maximum potential load that may be drawn from the system without tripping or failing.

In practice, the highest continuous current trip setting ensures that the disconnect can accommodate temporary fluctuations in load without compromising safety. This is especially important in systems where various circuit breakers might be set to trip at different levels based on the individual loads they serve. By sizing the service disconnect to the highest trip setting, it guarantees that the service remains reliable and can handle peak demands.

The other options are not ideal for determining the rating of a service disconnect. For instance, the average load rating does not account for peak loads and may underestimate the necessary capacity. Similarly, considering the load of all connected devices or the sum of all service loads can lead to overestimating or complicating the rating process since it does not directly address the tripping characteristics of the devices installed. Thus, basing the service disconnect rating on the highest continuous current trip setting of any installed breaker is both practical and aligned with the safety provisions of the NEC.