Bus Duct Ampacity

[PhaseShift]

When using bus duct what table do you use for the ampacity of the bus duct? Do you use 310.16? Can you use the 90deg C column or must you use the 75deg column still?

 

[charlie b]

It is not in the NEC tables. You tell the manufacturer what ampacity you need, and they sell it to you.

 

[Smart $]

When using bus duct what table do you use for the ampacity of the bus duct? Do you use 310.16? Can you use the 90deg C column or must you use the 75deg column still?

The only ampacity requirement for busbar in the NEC that I'm aware of is in 366.23.

366.23 Ampacity of Conductors.

(A) Sheet Metal Auxiliary Gutters. Where the number of
current-carrying conductors contained in the sheet metal auxiliary
gutter is 30 or less, the adjustment factors specified in
310.15(B)(3)(a) shall not apply. The current carried continuously
in bare copper bars in sheet metal auxiliary gutters shall
not exceed 1.55 amperes/mm? (1000 amperes/in.?) of cross
section of the conductor. For aluminum bars, the current carried
continuously shall not exceed 1.09 amperes/mm? (700 amperes/in.?)
of cross section of the conductor.

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[jim dungar]

UL listed plug-in and feeder style bus duct is 100% rated.

 

[PhaseShift]

So is there no derating necessary for bus duct for ambient conditions or other such things etc...?

 

[jim dungar]

So is there no derating necessary for bus duct for ambient conditions or other such things etc...?

Absolutely, there may be.