Can an adjustable-trip circuit breaker be used to protect conductors rated at less than the maximum setting of the circuit breaker?
Circuit Breakers with Micrologic Trip Units
Yes, a circuit breaker can be applied at less than its maximum rating if the amp rating is adjusted to a level needed to protect the wire, and if access to the adjusting means is appropriately restricted. For Micrologic Trip Units, restricted access is accomplished by installing the MICROTUSEAL Trip Unit Seal onto the cover over the adjusting dials. This complies with NEC240-6(C), which states " ``A circuit breaker that has restricted access to the adjusting means shall be permitted to have an ampere rating(s) that is equal to the adjusted current setting (long-time pickup setting). Restricted access shall be defined as t located behind one of the following:
1. Removable and sealable covers over the adjusting means
2. Bolted equipment enclosure doors
3. Locked doors accessible only to qualified personnel``