#1 and #2 Insulated Wire

#1 Insulated
There is a wide range of electrical wire that may be classified as #1 insulated. Any wire that has strands the size of a 12 gauge, solid strand wire or larger and has the defined recycling market recovery. Often 1 through 6 AWG will qualify along with 10 and 12 AWG solid strand wire.
#2 Insulated Heavy
This wire is uncommon but still recycled. This will usually have a recovery similar to #1 insulated and includes MCM like wire that has a tin layer over the copper. There are other less common types of #2 insulated heavy also.
#2 Insulated
As mentioned with #1 insulated and the wide range of different wire types, there is even a wider range with #2 insulated. Most wire that has smaller strands than 12 AWG or a less, will be considered as #2 insulated. This includes but is not limited to 8 through 12 AWG stranded and any 14 through 30 AWG wire.

Most telecommunication wire will also be placed into #2 category. Some examples are: cat4, cat5, cat6 and other ethernet and standard phone cords. Another example of #2 insulated is most 110 outlet cords and extension cords. There is #2 high, #2 medium and #2 low in this category.
Romex
Very common wire used in wiring homes and is considered a mid-recovery insulated grade. Often you’ll find the price to be in between that of #1 insulated & #2 insulated wires.