100 ft. 14/2 Solid Romex SIMpull CU NM-B W/G Wire

You would have to check to make sure the 15 amp outlet is rated for 20 amp pass through. Most are but I would check before using.

If an individual wants to run the PVC electrical conduit underground, then the answer would be a simple "No". Any electrical wires (conductors) that are ran through electrical conduits that are buried underground must be U.L. approved for wet locations. Regular NM-B Romex is not approved for wet locations. The plastic outer sheath covering these conductors does not change this ruling. At some point, most PVC (and metallic) electrical conduits that are ran underground may/will leak and take on some amount of water. Even with the most careful initial installation, over a period of time, buried electrical conduits may become full of water due to simple condensation of water vapor. If you need to run electrical lines underground (in a residential application), first determine the required size of the conductors required, based upon the anticipated usage (total amps required) and the estimated total distance from the electrical panel to the load. To do this properly might require some assistance. Then use "UF" (Underground Feeder) cable. "UF" cable is approved for inside wiring, as well as for “direct burial” underground wiring. "UF" cable is usually grey in color. Standard NM (Romex) cable contains individual wires (some insulated and some not insulated) that are wrapped with paper and then covered by a relatively loose plastic sheath. "UF" cable also contains individual wires. But, with "UF" cable, all of the wires (conductors) are completely encased in a heavy, solid thermoplastic sheath. With "UF" cable, this encasement protects each wire from the others and does not allow moisture or other external elements to travel inside the cable. Buried "UF" cable may be run through PVC conduit for added physical protection, if desired. When electrical PVC is buried, the use of at least 3/4" PVC is mandatory. Other factors such as “conduit wire fill” limitations and "ease of wire pulling" may readily necessitate the use of larger size conduits. Also pay attention to the required minimum depth requirements when burying cable or conduit. And, always consider the possible need for a free cable locating service to come out and locate and mark any buried utility lines (gas, electric, telephone, cable tv, etc) before you dig.

Will this wire work for a 220 air compressor and maybe a welder

Of course.