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Can an adjustable trip circuit breaker be used to protect conductors rated at less than the maximum setting of the circuit breaker?
Issue:
Using an adjustable-trip breaker at less than its maximum setting
Product Line:
Circuit Breakers
Environment:
Powerpact and Masterpact Circuit Breakers with Micrologic Trip Units
Resolution:
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.
Using an adjustable-trip breaker at less than its maximum setting
Product Line:
Circuit Breakers
Environment:
Powerpact and Masterpact Circuit Breakers with Micrologic Trip Units
Resolution:
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.
NEC240.6(C) 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:
(1) Located behind removable and sealable covers over the adjusting means
(2) Located behind bolted equipment enclosure doors
(3) Located behind locked doors accessible only to qualified personnel
(4) Password protected, with password accessible only to qualified personnel
(2) Located behind bolted equipment enclosure doors
(3) Located behind locked doors accessible only to qualified personnel
(4) Password protected, with password accessible only to qualified personnel
For Micrologic Trip Units, restricted access may be accomplished by installing the MICROTUSEAL Trip Unit Seal onto the cover over the adjusting dials.
Released for:Schneider Electric Australia
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