Sub-Panel wire size question

[ajj73]

I am planning on installing a sub panel from a 200 amp main panel in an attached garage where the requirement will be 90 amps max. I have available for FREE enough 4 AWG Copper cable to make the run and I am trying to understand the NEC as it applies to breaker sizing for a sub panel. The run is less than 40 feet long and will be installed in EMT. I am trying to determine the appropriate I am having trouble understanding what part of the code applies for proper sizing. My instinct says that I can use table Table 310-15(b)(6) and use a breaker of 100 amps in the main panel. However, then I read Table 310-16 and I begin to think I need that I will need to upgrade to 2 AWG copper. Can someone clarify this for me?

 

[iwire]

You cannot use table 310-15(b)(6) because the feeder to the garage is not a main feeder to a dwelling unit.

 

[ActionDave]

Where is the 90A coming from? A vehicle charger maybe?

 

[ajj73]

Where is the 90A coming from? A vehicle charger maybe?

The load is mostly for metal working machines, welders, and separate HVAC in the garage.

 

[infinity]

#4 Cu could be used on a 90 amp OCPD if the connected load is 85 amps or less since it's rated for 85 amps @ 75° C. 90 amps is the next standard size.

 

[ajj73]

#4 Cu could be used on a 90 amp OCPD if the connected load is 85 amps or less since it's rated for 85 amps @ 75° C. 90 amps is the next standard size.

Thank you all for your help! Much appreciated