wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Sharpen (make more precise) the language used in the exception.
Cheers, Wayne
2) Selection of Ampacity. Where more than one ampacity applies for a given circuit length, the lowest value shall be used.
Exception: Where different ampacities resulting from ampacity adjustment and/or correction apply to portions of a circuit, the higher ampacity shall be permitted to be used if the total portion(s) of the circuit with lower ampacity does not exceed the lesser of 3.0 m (10 ft) or 10 percent of the total circuit.
Statement of Problem and Substantiation for Public Input
Different ampacities can result from a variety of differences: different ambient temperature, a different number of current carrying conductors, a change in conductor material, or a change in conductor size. To my understanding, this exception is intended only for the first two reasons, a change in the ampacity adjustment or correction along the length of a circuit. The proposed language makes it clear that changing conductor size or conductor material is not covered by the exception.
Without this change, a change in conductor size could reasonably be considered to be covered by the exception. So for example 10' of #8 Cu conductor could be inserted into a 100' long 125A feeder, and the exception as currently worded would allow the use of the higher 125A ampacity for the entire circuit.
Cheers, Wayne
2) Selection of Ampacity. Where more than one ampacity applies for a given circuit length, the lowest value shall be used.
Exception: Where different ampacities resulting from ampacity adjustment and/or correction apply to portions of a circuit, the higher ampacity shall be permitted to be used if the total portion(s) of the circuit with lower ampacity does not exceed the lesser of 3.0 m (10 ft) or 10 percent of the total circuit.
Statement of Problem and Substantiation for Public Input
Different ampacities can result from a variety of differences: different ambient temperature, a different number of current carrying conductors, a change in conductor material, or a change in conductor size. To my understanding, this exception is intended only for the first two reasons, a change in the ampacity adjustment or correction along the length of a circuit. The proposed language makes it clear that changing conductor size or conductor material is not covered by the exception.
Without this change, a change in conductor size could reasonably be considered to be covered by the exception. So for example 10' of #8 Cu conductor could be inserted into a 100' long 125A feeder, and the exception as currently worded would allow the use of the higher 125A ampacity for the entire circuit.