NEC 310-16 chart confusion (nyc area)

[NYC_NY]

hi i am new to this forum, recently i have a decision on wire size and amp with my co workers, i always see sub panels on a 60 amp breaker with #6 thhn wire, if you look at the nec chart, #6 wire is 55 amp. how they pass inspection with a 60amp breaker? isn't 100amp or less you size the cable 60c. let me know what you guys think.

 

[infinity]

What is the wiring method? If it's NM cable the ampacity is 60° C column of 310.15(B)(16). If it's MC cable or pipe and wire then you can use the 75° ampacity. At 55 amps you can still use a 60 amp OCPD via the next size up rule in 240.4(B) if the calculated load is 55 amps or less. BTW what code book are you using? The - format went out about two decades ago.

Welcome to the Forum.

 

[NYC_NY]

What is the wiring method? If it's NM cable the ampacity is 60° C column of 310.15(B)(16). If it's MC cable or pipe and wire then you can use the 75° ampacity. At 55 amps you can still use a 60 amp OCPD via the next size up rule in 240.4(B) if the calculated load is 55 amps or less. BTW what code book are you using? The - format went out about two decades ago.

Welcome to the Forum.

thank you for the input! nec 2008

 

[infinity]

This section goes along with the second part of your question:

110.14(C)(1) Equipment Provisions. The determination of termination provisions of equipment shall be based on 110.14(C)(1)(a) or
(C)(1)(b). Unless the equipment is listed and marked otherwise, conductor ampacities used in determining equipment
termination provisions shall be based on Table 310.15(B)(16) as appropriately modified by 310.15(B)(7).
(a) Termination provisions of equipment for circuits rated 100 amperes or less, or marked for 14 AWG through 1 AWG conductors, shall be used only for one of the following:
(1) Conductors rated 60°C (140°F).
(2) Conductors with higher temperature ratings, provided the ampacity of such conductors is determined based on
the 60°C (140°F) ampacity of the conductor size used.
(3) Conductors with higher temperature ratings if the equipment is listed and identified for use with such conductors.
(4) For motors marked with design letters B, C, or D, conductors having an insulation rating of 75°C (167°F) or higher
shall be permitted to be used, provided the ampacity of such conductors does not exceed the 75°C (167°F)
ampacity.
(b) Termination provisions of equipment for circuits rated over 100 amperes, or marked for conductors larger than
1 AWG, shall be used only for one of the following:
(1) Conductors rated 75°C (167°F)
(2) Conductors with higher temperature ratings, provided the ampacity of such conductors does not exceed the
75°C (167°F) ampacity of the conductor size used, or up to their ampacity if the equipment is listed and identified
for use with such conductors