In applying the 80 percent rule for continuous loads, what must be ensured?

• A. The circuit is on a dedicated service disconnect.
• B. The circuit breaker is not oversized for continuous loads.
• C. All loads must be operated at 50%.
• D. Only continuous loads on 30A or larger.

Answer: (B)

Continuous loads run for long periods, so the NEC requires that the current they draw not exceed 80% of the overcurrent protective device’s rating. To apply this rule, you must size the circuit breaker so that the continuous load current stays within 80% of the breaker’s rating. In practice, that means choosing a breaker that is not oversized for the expected continuous load—the breaker rating should be such that the continuous current is at or below 0.8 times the breaker rating. The other options don’t address this requirement: a dedicated service disconnect, operating all loads at 50%, or restricting to loads on 30A or larger aren’t about the 80% continuous-load rule.