Where do if find allowed amps for urd in code

Typically it would be in the old 310.15(B)(6), since URD is typically used for residential service entrance.

However, "URD" will not be found in the NEC, as it is a name for an assembly. Usually URD cable is aluminum wire that uses XLPE or XHHW insulation.

Good point. I always forget to mention that.
Although in the resi service sizing chart they don't mention insulation, just size, right?
Now I have to go look it up. :/

Yes, Table 310.15(B)(6), does refer to applicable insulation types .

Ah yes! In the title. Funny the things you overlook when you look st something so many times.



Table 310.15(B)(7) Conductor Types and Sizes for
120/240-Volt, 3-Wire, Single-Phase Dwelling Services and
Feeders. Conductor Types RHH, RHW, RHW-2, THHN,
THHW, THW, THW-2, THWN, THWN-2, XHHW,
XHHW-2, SE, USE, USE-2

Doncha just hate it when they hide stuff right in front of us? I do that all the time.