UL 60079,UL 827,UL 467,UL 508A,UL 1973,UL 307A,UL 307B
INDUSTRIAL CONTROL PANELS - UL 508A
SEPTEMBER 1, 2005
31.4.2 For power conversion equipment consisting of two or more ”common bus?inverter sections that are supplied from a single power supply converter, all sections shall comply with 33.1.2 and shall be protected by a single set of ul 508a branch protective devices installed in the line side of the converter section. The branch circuit protective devices shall be sized according to (a) or (b), whichever is smaller:
a) The maximum usable branch circuit protection specified in 31.3.1 for the largest motor in the group plus the full-load ampere ratings of all remaining motors and other loads in the group: or
b) The maximum specified branch circuit protection of the converter section.
31.4.2 effective April 25, 2003
31.4.3 The ampacity of the tap conductors, the internal conductors to individual loads, shall be:
a) Not less than 1/3 the ampacity of the branch circuit conductor, calculated as in 28.3.3; or
b) Not less than 1/10 the ampere rating of the branch circuit protection for the group for each motor circuit provided with a manual motor controller marked “Suitable as tap conductor protection in group installations ?and complies with the Standard for Industrial Control Equipment, UL 508. The conductors on the load side of the manual motor controller shall have an ampacity not less than calculated in 28.3.2.
Added 31.4.3 effective March 1, 2007
31.4.4 For a group that includes other (non-motor) loads, additional branch circuit fuses or inverse time circuit breakers shall be provided in each circuit in accordance with 31.5 ?31.8.
Exception: Where the ampere rating of the branch circuit protection ul 508a pdf determined in 31.4.1 does not exceed the applicable branch circuit protection requirements in 31.5 ?31.8 for a non-motor load in the group, additional branch circuit protection is not required.
Added 31.4.4 effective March 1, 2007
31.5.1 A single general-use receptacle shall be protected by a branch circuit protective device having an ampere rating not more than the ampere rating of the receptacle.
31.5.1 effective April 25, 2003
31.5.2 A duplex receptacle or two or more receptacles connected to the same branch circuit shall be protected by a branch circuit protective device having an ampere rating not more than the ampere rating of the receptacle.
Exception No. 1: A 20-ampere branch circuit protective device is able to be used with a receptacle rated 15 amperes.
Exception No. 2: Branch circuit protective devices having a rating that ul 60079 is smaller than the rating of the receptacle are able to be used with a receptacle intended for use only with a specific piece of equipment and marked in accordance with 59.1.
31.5.2 effective April 25, 2003