There are many differences between Romex® and SOOW cables because they were engineered to fit different applications. Some applications are indoors, some are outdoors, some are underground and some have a large amount of daily impact that the copper will need protection from.
Romex® 12/2 wire is designed with one strand of solid 12 AWG copper while SOOW 12/2 has 65 copper strands in each of the conductors designed specifically for flexibility. Since Romex® is more commonly snaked through walls and conduit it’s much easier for installers to have a stiff cable that holds its form while being pushed up a wall. On the other hand SOOW is a type of portable cord which is the same cable used to build extension cords. Having a flexible extension cord is always a bonus because it helps the coiling and uncoiling process along with carrying it from one location to the next.
The next major difference is the jacket of each cable. Romex® NMB cable has a thin PVC jacket simply manufactured to send multiple wires from point A to point B at once. It has no added protection towards moisture or chemicals that the outdoors could bring. SOOW cable has a thick rubber jacket built for flexibility, ware and tare from being constantly handled and resistance to water, oils and gasses due to being used outdoors.
SOOW is one of the few cables that does NOT come with an additional ground wire on top of the designated number of conductors. Romex® 12 AWG 2 conductor will come with a 3rd wire as a bare copper ground wire. SOOW 12 2 cable comes with a total of 2 wires that are insulated and that’s it.
Two similarities between the cables are their voltage rating of 600 volts and their amperage rating. Since a 12 AWG wire is a 12 AWG wire whether it has 1 strand of copper or 65 strands it will carry the same amount of AMPS.
As you can see from this article it’s easier to discuss the differences between the two cables than it is to discuss the similarities. If you’re confused about the type of protection your electrical wire needs than you should speak to your supplier or wire and cable. They are great at understanding the different approvals of each cable and whether it can be used in certain locations or not. Your electrician can help you figure out the size of the cable you need to meet the NEC code when the installation gets inspected.
WesBell Electronics is a wire and cable distributor that stocks Romex® and all types of hook up wire. Romex® 12 2 wire is a common item that we have in our inventory in 2 or 3 conductor with an additional ground wire included.