ul/breakers
- Thread starter sam cotan
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those values are the limits of the terminations see 110.14(C)
there is another temp rating on most breakers (usually 40 deg), that number is the max ambient operating temp
- Location
- Massachusetts
To add to cpals info it is Celsius not Fahrenheit
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Actually those are the conductor termination temperature limits.
The breaker ambient air temperature limitations are significantly lower like 40?C.
Seriously, a 60/75?C breaker means you can use either 60? or 75?C conductors. The choice is yours.
The breaker ambient air temperature limitations are significantly lower like 40?C.
Seriously, a 60/75?C breaker means you can use either 60? or 75?C conductors. The choice is yours.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
It depends, Are you using a 90?C sized conductor or one with 90?C insulation?:grin:
- Location
- Massachusetts
Jim, I think I recall reading when a breaker is rated 60/75 that the 60 rating is to be used when the breaker is lined up alongside other breakers and that the 75 rating can only be used with breakers mounted singly.
Is there any truth to that or am I just all wet? :smile:
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
It means the breaker can be used with the old style (i.e. rubber) insulation without its 'heatsink' effect overheating the conductors.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Could be both. :grin:
See page 10 of the UL Circuit Breaker Marking Guide that is on the UL website as well as in the back of the UL WHite Book in Appendix A.
The excerpt reads:
60/75?C Wire ? All circuit breakers rated 125 A or less are marked for use with 60? C,
60/75?C or 75?C only wire. This marking indicates the proper wire size for termination in
accordance with Table 310.16 of the NEC . It is acceptable to use wire with a higher
insulation rating if the ampacity is based on the wire temperature rating marked on the
breaker. For breakers rated more than 125 A, the proper wire temperature rating is 75?C and
it is optional for the breaker to bear this marking.
The excerpt reads:
60/75?C Wire ? All circuit breakers rated 125 A or less are marked for use with 60? C,
60/75?C or 75?C only wire. This marking indicates the proper wire size for termination in
accordance with Table 310.16 of the NEC . It is acceptable to use wire with a higher
insulation rating if the ampacity is based on the wire temperature rating marked on the
breaker. For breakers rated more than 125 A, the proper wire temperature rating is 75?C and
it is optional for the breaker to bear this marking.
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