Services & DistributionQuestion 28 of 521
For circuits rated over 800 A, what is the rule for the overcurrent device relative to conductor ampacity?
a.Next higher standard size is allowed
b.It may be twice the ampacity
c.The OCPD rating must not exceed the conductor ampacity
d.There is no limit
Explanation
Per 240.4(C), where the circuit is over 800 A, the ampacity of the conductors must be equal to or greater than the OCPD rating; the next-size-up allowance of 240.4(B) does not apply. Doubling or 'no limit' are never correct.
Law Reference: 2023 NEC §240.4(C)Practice all 521 questions free — no signup required.
Related questions on this topic
- What is the maximum overcurrent protection allowed for a 12 AWG copper conductor under the small-conductor rule?
- Which of the following is NOT a standard ampere rating for a fuse or inverse-time breaker per 240.6(A)?
- A conductor has an allowable ampacity of 115 A that does not match a standard fuse size. The load is 112 A. What is the largest standard OCPD permitted?
- A service uses 3/0 copper conductors at 75 C (200 A ampacity) with a 200 A load. What is the correct standard OCPD?
- As a general rule, where must overcurrent protection for a conductor be located?
- Why is a service disconnect required to be readily accessible and located near the point of entrance of the service conductors?
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